Seminars 2012

Title:Around White phosphorus. Metal phosphide Nanoparticles: synthetic strategies and mechanisms; transition metal controlled activation
Speaker:Professor Nicolas Mézailles
Date:27 December 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor So Cheuk Wai

 

Title:Structural Transition in Soft and Biological Systems
Speaker:Professor Lingyun Zhang
Date:21 December 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract:

The experimental and theoretical progresses in the structural transition of soft and biological systems will be reviewed. With the aid of several examples, the mechanism of phase transition is to be explored. First of all a spin dynamic algorithm was developed to find a stable orientation configuration for an arbitrary alignment of the magnetic dipole moment, which accurately predicted the lattice constant variation as a function of the magnetic field, yielded excellent agreement with experimental results, and illustrated the formed reason of structural transition in magnetic colloidal system. Next phase behavior and transition of diblock copolymer in selective solvents were studied using self-consistent field theory, the detailed comparisons with the experimental phase diagrams including lamellar, cylindrical and spherical structures have been presented and the exact FCC-BCC structural phase transition temperatures in moderately and strongly selective solvents are calculated. Then a method of double strand DNA denaturation was proposed by employing spFRET, where it is demonstrated that both weak laser and fast impulse force determine the DNA melting, whose potential application is that the weak laser can pinpoint to control DNA denaturation process. Finally some new results, such as the statistical properties of biopolymer in the geometric confinement as well as the interaction between DNA and anti-cancer drug, are to be introduced.

 

Title:Recent progress for energy decomposition analysis
Speaker:Professor Peifeng Su
Date:20 December 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract:

Energy decomposition analysis (EDA) is a useful tool for understanding the intermolecular interactions in the framework of quantum chemistry. In this talk, the recent developed LMO-EDA and EDA-PCM methods are presented. The LMO-EDA is an energy decomposition analysis for interactions in gas phase with HF or KS orbitals. Decomposing the total interaction energy into electrostatic, exchange, repulsion, polarization, and dispersion interaction terms, the LMO-EDA method is able to investigate nonbonding and bonding interactions with closed or open shell systems. The EDA-PCM method is a free energy decomposition scheme for analyzing the intermolecular interactions invarious solvated environments based on LMO-EDA. In EDA-PCM, the solvated environment can be treated by CPCM, IEFPCM or Het-CPCM methods. The EDA-PCM is able to obtain the smooth curves of the total interaction energy and the individual EDA interaction terms in different dielectric environments along the whole potential energy surfaces. Test calculations show that the EDA-PCM is competent for various kinds of intermolecular interactions in various dielectric environments.

Bibliography (1) Su, P.; Li, H., J. Chem. Phys., 2009, 131, 014102 (2) Su, P.; Liu, H.; Wu, W. J. Chem. Phys. 2012,137, 034111

 

Title:Recent Advances in Ab Initio Valence Bond Methods
Speaker:Professor Wei Wu
Date:20 December 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract:

In this talk, I would report some recent advances in the methodology developments of valence bond theory.[1] This talk will focus on the ab initio VB methods that are based on classical VB theory, which deal with purely localized orbitals and explicit considerationof covalent and ionic structures. Post-VBSCF methods, valence bond configuration interaction method (VBCI) and the valence bond second order perturbation method (VBPT2), will be reported in this talk. In the VBCI method, the VBSCF energy and wave function are improved by configuration interaction (CI). On the other hand, VBPT2 uses perturbation theory, taking the VBSCF wave function as the zeroth order reference. In addition, a hybrid method, called density functional valence bond (DFVB), is also discussed, which uses DFT to correct dynamic correlation to VB energy. Furthermore, several VB applications to the nature of chemical bonding are discussed.

Bibliography Wu, W.; Su, P.; Sason, S.; Hiberty, P. C., Chem. Rev. 2011, 111, 7557-7593

 

Title:Construction of Multisubstituted Cyclic Compounds by Using Palladium and Sulfur as Key Elements
Speaker:Professor Hideki Yorimitsu
Date:18 December 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

Many multisubstituted cyclic compounds are known to be useful, but constructions of these skeletons as well as installation of substituents are laborious and thus to be improved. In this talk, the following topics will be presented: 1) Synthesis of multisubstituted heteroaromatics from ketene dithioacetal monoxide under Pummerer conditions and its application to material science, 2) Palladium-catalyzed arylative cyclization of propargyl- and homopropargylmalonates.

 

Title:Transition-Metal Catalyzed Cleavage of Si-Me Bond and Silyl C-H Bond in a Si-Me3 Group: Synthesis of Silacycles
Speaker:Professor Zhenfeng Xi
Date:11 December 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Koichi Narasaka
Abstract:

Silicon possesses some crucial differences from carbon (eg. covalent radius and electro-negativity). Thus, when a carbon atom is replaced by a silicon atom (the C/Si switch), the chemical and physicochemical properties of an organic compound may be changed dramatically. For example, silacyclopentadiene (often named silole) as organic material of electronic and opto-electronic devices demonstrates much superiority to its carbon-analogue, cyclopentadiene. In particular, the C/Si switch strategy has been applied successfully for odorant design and pharmaceutical applications. Furthermore, specific properties can be expected from totally new silicon-containing compounds, of which the carbon analogues cannot be synthesized or are very difficult to make. Thus, as a consequence, the development of synthetic methods for silacyclic compounds remains one of the most important frontiers in synthetic chemistry. The C(sp3 )-Si bond and silyl C(sp3 )-H bond in trialkylsilyl groups such as SiMe3 are among the most frequently encountered C-Si and C-H bonds, because many compounds are substituted with trialkylsilyl groups. Thus, a transition metal catalyzed coupling reaction accompanied with selective cleavage of the trialkyl C(sp3 )-Si bond1 and silyl C(sp3 )-H bond2 would be of great challenge and would lead to a synthetically useful protocol for the synthesis of diversified silacycles.3 In this presentation, synthetic methods recently developed in this research group along this line will be introduced.

References: 1. (a) Liang, Y.; Zhang, S.; Xi, Z. J. Am. Chem. Soc. 2011, 133, 9204. (b) Liang, Y.; Geng, W.; Wei, J.; Xi, Z. Angew. Chem. Int. Ed. 2012, 51, 1934. See also: Tobisu, M.; Onoe, M.; Kita, Y.; Chatani, N. J. Am. Chem. Soc. 2009, 131, 7506. Onoe, M.; Baba, K.; Kim, Y.; Kita, Y.; Tobisu, M.; Chatani, N. J. Am. Chem. Soc. 2012, 134, DOI: 10.1021/ja3096174. 2. Liang, Y.; Geng, W.; Wei, J.; Ouyang, K.; Xi, Z. Org. Biomol. Chem. 2012, 10, 1537. See also: Ohmura, T.; Torigoe, T.; Suginome, M. J. Am. Chem. Soc. 2012, 134, 17416. 3. Ouyang K.; Liang, Y.; Xi, Z. Org. Lett. 2012, 14, 4572.

 

Title:Invention of New Reactions for the Synthesis of Nitrogen Heterocycles
Speaker:Professor Michael Shipman
Date:7 December 2012
Time:3:30pm – 4:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract:

Nitrogen heterocycles play a central role in the chemical sciences, for example in drug discovery, and efficient methods for their synthesis are still much needed. This talk will highlight several pieces of new chemistry focused on the synthesis of pharmaceutically relevant nitrogen heterocycles developed in our laboratory. It will focus on multi-component reactions (MCR) and other modular strategies that offer potentially flexible routes to compounds with high levels of structural diversity.

 

Title:The design, synthesis, and applications of new organometallic catalysts for ketone reduction
Speaker:Professor Martin Wills
Date:7 December 2012
Time:2:30pm – 3:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract:

There is still an unmet need for efficient, robust and selective catalysts for a range of synthetic organic transformations. This talk will describe the structure and mechanisms of a number of highly active organometallic catalysts, primarily based on Ru, Rh and Fe, which have been developed in our group for the asymmetric reduction of ketones to enantiomerically-enriched alcohols. The mechanisms by which the catalysts operate, the concepts which we have used in their design, and the variety of applications to which they can be applied, will all be discussed in this lecture

 

Title:Elucidating and exploiting novel biosynthetic C-H functionalization reactions
Speaker:Professor Greg Challis
Date:7 December 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Xing Bengang
Abstract:

C-H functionalization reactions are key steps in the biosynthesis of numerous bioactive natural products. Such reactions include specific hydroxylation, chlorination and desaturation of unactivated carbon atoms, as well as a variety of oxidative cyclization reactions, exemplified by the conversion of the tripeptide ACV to the bicyclic penicillin nucleus. Here we report two unprecedented types of enzyme-catalyzed C-H functionalization reaction in natural product biosynthesis. RedG and McpG, novel Rieske non-heme iron dependent oxygenase-like enzymes, catalyse the regio- and stereodivergent oxidative carbocyclization of undecylprodigiosin to streptorubin B and metacycloprodigiosin, respectively, and TxtE, a unique cytochrome P450, catalyzes regiospecific nitration of L-tryptophan, the first committed step in thaxtomin phytotoxin biosynthesis. Efforts to elucidate the catalytic mechanisms of these enzymes and to exploit them for the production of novel streptorubin B and nitrotryptophan derivatives will be described.

 

Title:New Approaches to Asymmetric Catalyst Design and Optimization
Speaker:Professor Matthew S. Sigman
Date:6 December 2012
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

There has been remarkable progress in asymmetric catalysis since the inception of the field three decades ago and, chiefly, over the last decade. Because of this, asymmetric catalysis now provides chemical researchers in both academia and industry with the means todirectly access useful enantiomerically enriched compounds. With advances in technology (i.e. high throughput screening), the identification of an asymmetric catalyst that promotes a transformation in high enantiomeric excess has been expedited. However, the approach to catalyst identification remains mainly empirical, wherein evaluation of a significant number of ligands, often structurally unrelated, is required to develop a mature chiral catalyst. Therefore, the central goal of our program is focused on developing general methods that facilitate the rapid design and optimization of new asymmetric catalysts for challenging, synthetically useful transformations. The lecture will focus on our recent efforts to evaluate structure-enantioselectivity relationships as a function of ligand structure to facilitate catalyst design and optimization. A particular focus will be on classic physical organic mechanistic tools in combination with multi-dimensional statistical approaches.

 

Title:Catalytic Chirality Generation: New Strategies for N-Heterocyclic Chemistry
Speaker:Professor John Bower
Date:26 November 2012
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Koichi Narasaka
Abstract:

Recent studies form our laboratory aimed at generating chiral N-heterocyclic scaffolds will be presented. The talk will focus upon the Pd(0)- catalysed cyclisation of oxime esters with alkenes (the Narasaka-Heck reaction)1 as a means of accessing a variety of chiral and enantioenriched cyclic imines.2,3 Synthetic and mechanistic aspects of the chemistry will be discussed.

References 1. M. Kitamura and K. Narasaka, Chem. Rec. 2002, 2, 268. 2. A. Faulkner and J. F. Bower, Angew. Chem. Int. Ed. 2012, 51, 1675. 3. A. Faulkner, J. S. Scott and J. F. Bower, Unpublished results.

 

Title:Nitroxides and Quinones as mild Oxidants in Catalysis
Speaker:Professor Armido Studer
Date:26 November 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Robin Chi 
Abstract:

In the presentation novel applications of the persistent TEMPO radical as an environmentally benign oxidant in catalysis will be discussed. We will show that TEMPO can be applied in Pd-catalyzed oxidative C-C-bond forming processes. 1 Direct C-H-arylation of arenes and carboaminoxylations of indoles and indenes can be achieved via this method. 2 In the latter process the nitroxide acts both as oxidant and as reagent. Oxidative Heck-chemistry can also be conducted by using TEMPO or related nitroxides as mild terminal oxidants. 3 Finally we will focus on the use of nitroxides and quinones as organic oxidants in biomimetic aldehyde oxidations. 4 Oxidative esterifications and redox activation of Michael acceptors will be presented along with mechanistic studies. 5

References 1. L. Tebben, A. Studer, Angew. Chem. Int. Ed. 2011, 50, 5034. 2. a) S. Kirchberg, R. Fröhlich, A. Studer, Angew. Chem. Int. Ed. 2009, 48, 4235. b) S. Kirchberg, R. Fröhlich, A. Studer, Angew. Chem. Int. Ed. 2010, 49, 6877. c) S. Kirchberg, S. Tani, K. Ueda, J. Yamaguchi, A. Studer, K. Itami, Angew. Chem. Int. Ed. 2011, 50, 2387. d) M. Steinmetz, K. Ueda, S. Grimme, J. Yamaguchi, S. Kirchberg, K. Itami, A. Studer, Chem. Asian. J. 2012, 7, in press. e) K. Yamaguchi, J. Yamaguchi, A. Studer, K. Itami, Chem. Sci. 2012, 3, 2165. 3. Z. He, S. Kirchberg, R. Fröhlich, A. Studer, Angew. Chem. Int. Ed. 2012, 51, 3699. 4. a) S. De Sarkar, S. Grimme, A. Studer, J. Am. Chem. Soc. 2010, 132, 1190. b) S. De Sarkar, A. Studer, Angew. Chem. Int. Ed. 2010, 49, 9266. 5. R. C. Samantha, B. Maji, S. De Sarkar, K. Bergander, R. Fröhlich, C. Mück-Lichtenfeld, H. Mayr, A. Studer, Angew. Chem. 2012, 51, 5234

 

Title:Structural biology at Liverpool: Research activities and opportunities
Speaker:Professor Richard Strange
Date:22 November 2012
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract:

My educational background is in physics (Keele University PhD, 1984). My work has contributed to around 100 peer-reviewed research papers and book chapters (h-factor 32). In my early career, I made especially significant contributions to the biological applications of X-ray Absorption Spectroscopy (XAS), including the first demonstration of the importance of multiple scattering and the use of constraints and restraints in XAS data analysis. These developments have since become the standard methods used in BioXAS research worldwide. More recently, I have promoted through invited review papers and invited talks, the combined use of XAS and Protein Crystallography, highlighting the synergy between these techniques to bring together these two communities of researchers. I was a member of the XAFS IUCr dictionary work group, 2008-2010 and I am a co-editor of J. Synchr Radiation. I am a visiting scientists at RIKEN, since 2009. I am currently working on a structure-based project on human SOD1, which is focused on pathogenic mutations that cause motor neuron disease and am engaged, via a fragment-based approach, to identify potential drug-like molecules that would alleviate or inhibit disease onset or progression. Molecular dynamics is also a major component of this research programme. Enzymes from the bacterial denitrification pathway, part of the global nitrogen cycle with obvious environmental significance, have been part of my research activities for several years, targeting the key structural features relevant to the catalytic mechanisms (nitrite binding and turnover). Preparations for future applications of the powerful XFELs to biological systems has been a recent area of interest.

 

Title:The Combination of Metal and Organocatalysis for Asymmetric Synthesis
Speaker:Professor Liu-Zhu Gong
Date:15 November 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract:

Traditionally, either metal based or organocatalysts are generally used alone to promote fundamentally different reactions in asymmetric catalytic processes.1 The combination of metal complexes and organic molecules in cooperative and relay catalysis may enable new transformations through the simultaneous or sequential activation and reorganization of multiple chemical bonds by the metal- and organocatalysts. This concept holds great potential in creating a broad scope of organic synthetic reactions, as previously demonstrated by transformations accelerated by metal/organic binary catalyst systems.2 My group has long been involved in this rising field,3 in particular, recently centered on the development of unprecedented asymmetric relay catalytic protocols (ARC reactions). As a result, we have demonstrated that the combined use of organocatalysts and transition metals in asymmetric catalysis.4 Herein, we will report some enantioselective transformations catalyzed by combined binary systems consisting of transition metal complexes and Brønsted acids, leading to the generation of chiral products with high optical purity.5-7

References: [1] (a) Comprehensive Asymmetric Catalysis; Jacobsen, E. N.; Pfaltz, A.; Yamamoto, H. Eds.; Springer-Verlag: Heidelberg, 1999. (b) Berkessel, A.; Groger, H. Asymmetric Organocatalysis; Wiley-VCH: Weinheim, 2005. [2] (a) Shao, Z.; Zhang, H. Chem. Soc. Rev. 2009, 38, 2745. (b) Zhong, C.; Shi, X. Eur. J. Org. Chem. 2010, 2999. (c)Han, Z.-Y.; Wang, C.; Gong, L.- Z. In Science of Synthesis, Asymmetric Organocatalysis; List, B., Maruoka, K., Eds.; Georg Thieme Verlag: Stuttgart, 2011, section 2.3.6 [3] (a) Chen, G.; Deng, Y.; Gong, L.; Mi, A.; Cui, X.; Jiang, Y.; Choi, M. C. K.; Chan, A. S. C. Tetrahedron: Asymmetry 2001, 12, 1567. (2) Hu, W.- H.; Xu, X.-F.; Zhou, J.; Liu, W.-J.; Huang, H.-X.; Hu, J.; Yang, L.-P.; Gong, L.-Z. J. Am. Chem. Soc. 2008, 130, 7782. [4] (a) Han, Z.-Y.; Xiao, H.; Chen, X.-H.; Gong, L.-Z. J. Am. Chem. Soc. 2009, 131, 9182. (b) Wang, C.; Han, Z.-Y.; Luo, H.-W.; Gong, L.-Z. Org. Lett. 2010, 12, 2266. [5] Han, Z.-Y.; Chen, D.-F.; Wang, Y.-Y.; Guo, R.; Wang, P.-S.; Wang, C.; Gong, L.-Z. J. Am. Chem. Soc. 2012, 134, 6532-6535. [6] Ren, L.; Lei, T.; Ye, J.-X.; Gong, L.-Z. Angew. Chem. Int. Ed. 2012, 51, 771-774. [7] Unpublished Results.

 

Title:Hard X- and Soft X- PES Investigation of Nanostructured PEM Fuel Cell Catalysts
Speaker:Professor Vladimir Matolin
Date:12 November 2012
Time:12:00pm – 1:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Martin Pumera
Abstract:

Powering of electronic devices by microfabricated power sources, including micro-proton exchange membrane fuel cells (m-PEMFC), are being actually investigated in laboratories world-wide. The possibility of co-fabrication of a power source on the same substrate as the electric circuit offers many advantages, including a reduction in size and weight, increased processing efficiency, and lowercost. The important issue of planar type fuel cells is a preparation of large specific surface area catalysts grown by thin film deposition techniques which are compatible with planar technology.

Recently we showed by fuel cell activity and electron microscopy measurements the possibility of preparation of porous large surface and high activity nanostructured thin film catalysts by depositing the catalysts in form of Pt-Ce-O solid solutions on different carbon substrates by magnetron sputtering. Figure shows example of CNTs coated by the porous Pt-CeO2 catalyst film. Chemical composition of the films was investigated by x-ray synchrotron radiation photoelectron spectroscopy in soft and hard X ray region. Resonant PES has been performed by measuring Ce 4f resonant profiles of both Ce4+ and Ce3+ states. The Pt-doped sputtered cerium oxide films contained high concentration of cationic platinum Pt2+ and Pt4+ which were highly active species for hydrogen dissociation to protonic hydrogen H+ .

 

Title:Nrf2-Keap1 interaction: A double-edged sword in metabolic disorders and cancer therapy
Speaker:Professor Ramasamy Paulmurugan
Date:8 November 2012
Time:2:00pm – 3:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Xing Bengang
Abstract:

The major failure in treatment-response to anticancer drugs is due to drug resistance in cancer cells through the activation of endogenous antioxidant detoxification mechanisms. At the same time, the cellular failure for antioxidant detoxification mechanism has been considered a major factor responsible for the destruction of -cells in diabetes. Cells maintain their redox homeostasis by developing mechanisms that protect them from oxidative stresses. Since this mechanism is so well designed by nature to protect cells from free radicals produced during oxidative stresses in their aerobic environment, it presents a major obstacle for tumor cells responding to chemotherapy. Nrf2-Keap1 pathway regulates cellular redox homeostasis and hinders cancer therapy in the clinic. Similarly failure in Nrf2-Keap1 pathway in -cells causes diabetes. Nrf2 is a transcription factor expressed in cells that protects cells from oxidative stresses by inducing antioxidant enzymes. We have extensively used split-reporter protein fragment-complementation assay to optically measure protein-protein interactions, protein folding, and protein dimerizations in cells and noninvasively imaging them in live animals. However, it has not been used for designing sensors to study the cellular chemoprotective antioxidant mechanism, which is an important hallmark pathway that makes drug resistance in cancer therapy, and -cell dysfunction in diabetes. We developed split-optical reporter complementation sensors to ratiometrically evaluate the oxidative stress induced by chemotherapeutic drugs and antioxidants. The ratiometric sensors can be used to preclinically demonstrate the drug-induced antioxidant chemoprotective (cytoprotective) mechanism of cancer cells in living animals. Additionally, ratiometric sensors can be used for screening new drugs capable of effectively killing cancer cells without activating this endogenous drug resistant mechanism in cancer, and also for identifying and evaluating antioxidants which can improve -cell function in diabetes.

 

Title:Comprehensive and Practical Solutions to Chiral 1,2-Diamine Synthesis and Enantioselective Aldehyde Crotylation
Speaker:Professor Hyunwoo Kim
Date:8 November 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Sunggak Kim
Abstract:

Chiral vicinal diamines, or 1,2-diaminoethanes, are regarded as a ‘privileged’ ligand for developing stereoselective catalysts such as Noyori’s and Jacobsen’s catalyst. Moreover, the vicinal diamino functionality has been found in several bioactive compounds such as Tamiflu, Relenza, Lorabid, and Eloxatin. Although there is much current interest in preparation of chiral vicinal diamines, it has been a challenge to develop efficient and general synthetic methods. We have developed the preparation of chiral vicinal diamines based on the resonanceassisted hydrogen-bond (RAHB) directed diaza-Cope rearrangement (DCR) where the strong hydrogen bonds can shift the equilibrium of the DCR reaction to completion. Over the several years of our research, the DCR method has been proved to be one of the most efficient methods for preparing a variety of chiral vicinal diamines, including not only C2 -symmetrical diaryl diamines but also dialkyl diamines and even mixed aryl-aryl or alkyl-aryl diamines.

The prevalence of secondary alcohol motifs in biologically active polyketides and other natural products has led to the development of various enantioselective reagents for the crotylation of aldehydes. In fact, the method of Brown is one of the most open-employed methods in all of asymmetric synthesis, and it is difficult to overstate the importance of this reaction. Despite the popularity of the Brown method in particular and of the reaction type in general, a strong case can be made that the problem has still not been truly solved. In the present presentation I will discuss the challenges of the aldehyde crotylation and how these problems can be solved.

 

Title:Multicomponent Radical Reactions: Back to the Basics
Speaker:Proefessor Ryu Ilhyong
Date:7 November 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

Multicomponent reactions continue to attract considerable attention in organic synthesis driven by a desire to generate structural diversity from simple small molecules. For decades, tin reagents have been used as most popular mediators of radical reactions. Recent research has focused on seeking greener reagents as an alternative to tin and this led us to reconsider the potential of traditional radical chemistry for multicomponent reactions. Indeed we have been able to exploit the well known behavior of bromine radicals to add to unsaturated C-C bonds to develop novel three- and four-component radical reactions.1 In addition the utility of photo-catalytic systems have also been pursued in our laboratory. Three component coupling between alkanes, carbon monoxide, and electron-deficient alkenes in the presence of a catalytic amount of (nBu4N)4W10O32 (TBADT) resulted in the efficient formation of unsymmetrical ketones.2 A Pd/light system has also been developed for the reaction of alkyl halides, alkenes, carbon monoxide and nucleophiles.3 We also discuss the potential of (nBu4N)BH3CN to act as a radical mediator of reductive radical chain reactions, which has enabled us to employ formaldehyde in radical hydroxymethylation reactions.4

1) Kippo, T.; Fukuyama T.; Ryu, I. Org. Lett. 2011, 13, 3864. 2) Ryu, I., Tani, A., Fukuyama, T., Ravelli, D., Fagnoni, M., Albini, A. Angew. Chem. Int. Ed., 2011, 50, 1869. 3) Fusano, A.; Sumino, S.; Nishitani, S.; Inouye, T.; Morimoto, K.; Fukuyama, T. Chem Eur. J. 2012, 18, 9415. 4) Kawamoto, T.; Fukuyama, T.; Ryu, I. J. Am. Chem. Soc. 2012, 134, 875.

 

Title:Chelating “Click” Ligands for Metal-Mediated Catalysis
Speaker:Dr Preeyanuch Sangtrirutnugul
Date:5 November 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Choon Hong
Abstract:

Heterocyclic 1,4-disubstituted-1,2,3-triazole is generally prepared from one of the most commonly used “click” reactions, the coppercatalyzed azide/alkyne cycloaddition (CuAAC). This type of compound has found many applications including biochemical studies, drug delivery, and functionalized polymer and material. However, examples of its role as catalyst support for metal-mediated chemical transformations have been limited. We are interested in preparing new chelating ligands featuring 1,2,3-triazole rings and their corresponding transition metal complexes. Catalytic activities of these complexes toward atom transfer radical polymerization (ATRP) and C-C bond coupling will be discussed and compared with other known and structurally similar catalysts.

 

Title:Total Synthesis of Bioactive Marine Diterpene Natural Products
Speaker:Professor Stephen Clark
Date:2 November 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract:

The cladiellins (e.g. vigulariol, 3-acetoxycladiella-6,11-diene, sclerophytin A and polyanthellin A) are a large group of ether-bridged diterpene natural products of marine origin that possess a wide range of biological activities including cytotoxic activity against tumour cells. The structural complexity of these marine natural products coupled with their biological activities makes them highly attractive targets for total synthesis.

We have developed a general strategy that is applicable to the synthesis of the entire cladiellin family of natural products. The key step for assembly of the tricyclic core of the cladiellins involves reaction of the diazo ketone 1 with a suitable transition metal complex to give a free or metal-bound oxonium ylide that undergoes stereoselective rearrangement to produce the bridged ethers Z-2 and E-2 in excellent yield. Remarkably, the reaction can be tuned to give either isomer as the major product simply by selecting the appropriate catalyst and reaction conditions. Subsequent elaboration of these O-bridged bicyclic ethers gives the tricyclic ketones Z-3 and E-3 which can be elaborated to give a wide variety of cladiellin natural products.

 

Title:Structure Elucidationof Natural Products: Navigating Through the Stereochemistry Maze
Speaker:Dr Yeun-Mun Choo
Date:31 October 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Choon Hong
Abstract:

The nature has been a well-tested source for producing structurally intriguing chemical compounds. It was reported that approximately 50% of the drugs currently in market for various treatments have its origin from natural sources. In many instances, these chemical compounds contain stereocenters which gave rise to the specific stereoconfiguration and/or conformation of the compounds. It is evident that the stereochemistry of chemical compounds have significant implication on the biological activities as the enzymes and receptors are highly selective. Hence, in addition to elucidating the skeletal structure of the chemical compounds, the assignment of the stereocenter’s configurations carries equal importance when reporting the structure of the compounds.

With the advancement of modern technology, various spectrometry methods are available to shed lights on the configuration of stereocenters. Spectroscometry method such as X-ray crystallography and electronic circular dichroism (ECD) has been gaining momentum in assisting the assignment of stereocenter’s configurations in the chemical compounds. However, the inability to obtain samples in its suitable form are hampering the use of these methods, e.g. crystals in the case of X-ray and suitable models for electronic circular dichroism (ECD), and hence, NMR spectroscopy is still heavily relied upon for the assignments of stereocenters. This paper dwells on the theme of stereochemistry in the backdrop of the process of structure elucidation of compounds from natural products. The process is hardly straight forward but the hints are always clear if one is willing to give a second thought.

 

Title:Natural Product Total Synthesis And What We Learned In-Between
Speaker:Professor Craig Williams
Date:29 October 2012
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract:

Human health and agriculture have benefitted greatly from natural products, or derivatives thereof, in terms of both medicines in the clinic and the control of crop pests. Behind the scenes natural product total synthesis (or derivatisation) is an absolute requirement to confirm structure and manipulate these often complex molecules. Omnipresent in this field are opportunities to provide student training and stimulate academic learning. Often, however, natural product total synthesis projects are fraught with much difficulty for exemplar reasons such as literature chemistry failing to deliver, or simply because the chemical methodology is currently unavailable to achieve the desired transformation (i.e. functional group interconversion). The adventures of working on natural product targets, such as above (Figure 1), highlight these points and the lecture will detail successful and unsuccessful encounters along with aspects of physical organic and organometallic chemistry used to address these situations.

Acknowledgement: The authors thank the University of Queensland, EcoBiotics Pty Ltd, CSIRO and the Australian Research Council for financial support.

 

Title:Protein Recognition of Bacterial Glycans Containing Furanose Residues
Speaker:Professor Todd Lowary
Date:25 October 2012
Time:2:00pm – 3:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Liu Xuewei
Abstract:Glycans containing five-membered furanose rings are present in a range of microbial species. The interaction between furanosecontaining glycans and proteins mediates a number of important biological events, but an understanding of these bind events remains poorly defined at the molecular level. Of particular interest to our group is the organism responsible for the disease tuberculosis, Mycobacterium tuberculosis, which produces an array of glycoconjugates containing furanose rings. The talk will focus on the synthetic and biophysical work done to probe the interaction between mycobacterial furanose glycans and two families of proteins: antibodies that recognize the cell wall antigen lipoarabinomannan and a glycosyltransferase that is involved in the biosynthesis of arabinogalactan, the largest structural component of the cell wall.

 

Title:Metal-insulator transition in Ti-based perovskites
Speaker:Professor Taras Kolodiazhnyi
Date:25 October 2012
Time:12:00pm – 1:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Martin Pumera
Abstract:In 1949 Mott first introduced the idea of the abrupt insulator-to-metal transition in the host material when the concentration of the charge carriers furnished by donor impurities exceeds a critical concentration nc . Since then the universality of this criterion has been proven over the range of 109 in critical concentration and over 600 Å in effective Bohr radii. Stoichiometric ATiO3 perovskites where A=Ba, Ca, Eu, Sr are band gap insulators. Charge carriers (and consequently conductivity) can be introduced in these perovskites by doping for example, with oxygen vacancies. Several recent studies [e.g., K.Szot et al., Phys. Rev. Lett. 88, 075508 (2002)] have shown evidence of partial clustering of the O vacancies as well as possible segregation of oxygen vacancies at the extended one-dimensional defects in the SrTiO3-x . Based on these novel findings it has been argued that electronic transport properties of SrTiO3-x are mainly controlled by these extended defects; and that the whole point defect chemistry and superconductivity in SrTiO3-x have to be revised. In this contribution I will show that there is no urgent need for such a drastic revision because the Mott criterion of the insulator-to-metal transition holds fairly well for n-type SrTiO3 , BaTiO3 , EuTiO3 and CaTiO3 ; especially when we take into account that the nc differs in these materials by more than three orders of magnitude. I will also compare electronic and magnetic properties of these compounds as revealed by the low-temperature specific heat, Seebeck and Hall coefficients, magnetic susceptibility, and optical data. Moreover, I will show that the polar lattice distortions partially survive in the metallic phase of BaTiO3 providing support for “ferroelectric metal” concept introduced by P.W. Anderson in 1965 [P.W. Anderson and E. I. Blount, Phys. Rev. Lett. 14, 217 (1965)]. 

 

Title:A Synthetic Chemist’s Approach to Chemical Biology: From Enzyme Inhibition, Natural Products Synthesis to In Vivo Imaging by 6π-Azaelectrocyclization
Speaker:Dr Katsunori Tanaka
Date:24 October 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:During inhibitory studies of the hydrolytic enzyme by aldehyde-containing natural products, a reaction involving 6π-azaelectrocyclization with lysines was discovered. Substituent effects within the 1-azatriene systems, the precursor of cyclization, accelerated the reaction. Structure-reactivity studies showed that the azaelectrocyclization, which usually proceeds in low yield at high temperatures, could be performed quantitatively in less than 5 min at rt. The asymmetric chiral piperidine synthesis and the one-pot library synthesis of pyridines on solid-supports were applied to the synthesis of pyridine / indole alkaloid-type natural products. A lysine-based labeling of biomolecules based on rapid 6π-azaelectrocyclization has also been developed. Both DOTA as a metal chelating agent (either for MRI, PET, or other radiopharmaceutical purposes, e.g., SPECT with gamma emitters) as well as fluorescent groups were introduced efficiently and selectively into lysine residues within 10 min at concentrations even at 10-8M. The DOTA-labeled somatostatin, glycoproteins, and glycoclusters were then radiometallated with 68Ga and the receptor-mediated accumulation of somatostatin in pancreas was observed. Further, oligosaccharide dependent circulatory residence of glycoproteins, and the specific accumulation of the N-glycanclusters could be visualized for the first time by microPET. "A whole cell-based in vivo imaging" via direct chemical labeling of living cells, the chemical engineering of antibodies and/or cell surfaces by natural N-glycans based on azaelectrocyclizations, and the combined solid-supported/microfluidic technologies toward oligosaccharides synthesis, will also be presented.

 

Title:Solid and Solution-Phase Synthesis for Natural and Unnatural Product Library
Speaker:Professor Takashi Takahashi
Date:22 October 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba

 

Title:Synthetic Studies on Polycyclic Natural Products
Speaker:Dr Jun Shimokawa
Date:15 October 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

Our interests rest in the synthesis of polycyclic natural products and the discovery of new reactivities within the framework of those complex molecules. Among those synthetic targets, I will talk mainly about the synthesis of amathaspiramide A-F and gelsemoxonine. Both natural products could be characterized by the small size and consecutive stereocenters. Details of the syntheses and the interesting reactivity of the synthetic intermediates will be focused..

 

Title:Quantum Chemical Study on Roles of Lewis Acids and Bases in Organic Reactions
Speaker:Professor Ken Sakata
Date:3 October 2012
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract:

Lewis acids and bases are fundamental concept in chemistry and these species are utilized for activation of a variety of organic reactions. In this presentation, I will show recent topics of our quantum chemical studies of organic reactions catalyzed by Lewis acids and bases, such as Lewis acid catalyzed allylboration, Lewis base catalyzed allylation, and Diels-Alder reactions catalyzed by Lewis acid activated oxazaborolidines.

 

Title:One-Pot Strategies for Carbohydrate Synthesis
Speaker:Professor Shang-Cheng Hung
Date:1 October 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Liu Xuewei
Abstract:

Carbohydrates are involved in numerous vital life processes. They are structurally diverse and complex as compared to other biopolymers (proteins and nucleic acids) and are present in micro-heterogeneous forms in nature. Chemical synthesis of carbohydrates, the practical route to procure pure oligosaccharides, is however hampered by two major hurdles, regioselective protection of polyhydroxyls and rapid assembly of glycosidic linkages involving the stereoselective control of α- or β-glycosidic bonds. Here, a novel, combinatorial, and highly regioselective method to protect individual hydroxyls of monosaccharide units and install an orthogonal protecting group pattern in a one-pot manner is presented, obviating the necessity to carry out intermittent tedious workups and time-consuming purifications. Hundreds of building blocks starting from D-glucose have been efficiently prepared. Iterative coupling of these building blocks to the assembly of β-1,6-glucans and one-pot synthesis of influenza virus-binding trisaccharide library using a sialyl donor as the starting sugar unit are demonstrated, respectively. Thereby, the combination of onepot protection strategy and one-pot glycosylation may offer an efficient protocol to solve the long-standing problem in carbohydrate synthesis.

 

Title:One-Pot Strategies for Carbohydrate Synthesis
Speaker:Professor Shang-Cheng Hung
Date:1 October 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Liu Xuewei
Abstract:

Carbohydrates are involved in numerous vital life processes. They are structurally diverse and complex as compared to other biopolymers (proteins and nucleic acids) and are present in micro-heterogeneous forms in nature. Chemical synthesis of carbohydrates, the practical route to procure pure oligosaccharides, is however hampered by two major hurdles, regioselective protection of polyhydroxyls and rapid assembly of glycosidic linkages involving the stereoselective control of α- or β-glycosidic bonds. Here, a novel, combinatorial, and highly regioselective method to protect individual hydroxyls of monosaccharide units and install an orthogonal protecting group pattern in a one-pot manner is presented, obviating the necessity to carry out intermittent tedious workups and time-consuming purifications. Hundreds of building blocks starting from D-glucose have been efficiently prepared. Iterative coupling of these building blocks to the assembly of β-1,6-glucans and one-pot synthesis of influenza virus-binding trisaccharide library using a sialyl donor as the starting sugar unit are demonstrated, respectively. Thereby, the combination of onepot protection strategy and one-pot glycosylation may offer an efficient protocol to solve the long-standing problem in carbohydrate synthesis.

 

Title:Detection of Biomolecular Recognition Using Bio-Transistors
Speaker:Professor Yuji Miyahara
Date:25 September 2012
Time:4:00pm – 5:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Martin Pumera
Abstract:

We have been investigating direct interaction between biomolecules and electrons in silicon. We have proposed the novel concept of a biotransistor (Bio-FET) which is based on the direct transduction of charge density change of biomolecules into electrical signal by the field effect. Potentiometric measurements of allele specific oligonucleotide hybridization, intercalation and primer extension at the surface of the gate insulator have been demonstrated using a genetic field effect transistor. Since DNA molecules are negatively charged in an aqueous solution, hybridization event at the gate surface leads to charge density change in the channel of the FET and can be transduced into electrical signal directly without any labeling for target DNA molecules. One of the unique features of our method is to utilize a single-base extension reaction on the gate for DNA sequencing. Single-base mismatch of the target DNA as well as DNA sequencing could be successfully demonstrated with the use of the genetic FETs [1]. The genetic FET platform is suitable for a simple, accurate and inexpensive system for SNP typing and high throughput DNA sequencing in clinical diagnostics and molecular biology.

We also propose an oocyte-based field effect transistor (oocyte-based FET) for drug transport analysis, in which target transporters are expressed at the cell membrane of the oocyte. Non-invasive monitoring of the uptake kinetics of substrates mediated by membrane-bound transporters can be realized with oocyte-based FET. Discrimination of transporting ability among genotypes of the transporters could be realized using the oocyte-based FET [2].

A label free, potentiometric method to detect cell surface sialic acid (SA) using phenylboronic acid (PBA) compound integrated into the form of self-assembled monolayer (SAM) has been developed using a field effect transistor (FET) extended gold gate electrode [3-4]. Due to predominant binding between undisassociated PBA and SA at pH 7.4, we found that carboxyl anions of SA were exclusively detectable among other glycan chain constituent monosaccharides, as the change in threshold voltage (VT ) of the PBA-modified FET. The technique was applied to analyses of altered SA expressions on rabbit erythrocyte as a model for diabetes, as shown in Fig. 1. The comparative analyses revealed that the disease could be feasibly diagnosed simply by placing the cell suspensions onto the device without any labelling and enzymatic procedures.

References [1] T. Sakata and Y. Miyahara, Angew. Chem. Int. Ed., 45, 2225-2228 (2006) [2] T. Sakata and Y. Miyahara, Anal. Chem. 80, 1493-1496 (2008) [3] A. Matsumoto, N. Sato, H. Cabral, K. Kataoka, and Y. Miyahara, J. Am. Chem. Soc., 131, 12022–12023 (2009). [4] A. Matsumoto, H. Cabral, N. Sato, K. Kataoka, and Y. Miyahara, Angew. Chem. Int. Ed., 49, 5494-5497 (2010)

 

Title:Fishing for Chloride in Salty Waters using Photoactive Foldamers
Speaker:Professor Amar Flood
Date:25 September 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract:

Chloride is an abundant ion that plays critical roles in human biology and chemical processes. For these reasons, mastering ways to manipulate its availability across many environments will have far-reaching consequences. We are focusing supramolecular chemistry onto this task by taking advantage of triazole-based receptors that are easy to make and modify. Taking inspiration from biology in the form of halorhodopsin, a new class of light-active foldamers has been created that can catch and release chloride to regulate its concentration. We will then move out of organic solvents, again taking biology’s lead, to tackle one of the grand challenges in host-guest chemistry: Extracting highly-hydrated chloride ions from aqueous solutions. We do so by employing the principles present in proteins like chloride channels (ClC), and for the first time with synthetic receptors, show that the hydrophobic effect can be used to extract hydrophilic guests equally as well as hydrophobic ones. Ultimately, we have learned about the important role that a foldamer’s helical propensity plays in determining its function.

 

Title:Organic Conductive Biomaterials: from Efficient Syntheses to Bioengineering Applications
Speaker:Professor Hsiao-hua Yu Bruce
Date:14 September 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Martin Pumera
Abstract:

The research of Yu Initiative Research Unit focus on the development of independent and multidisciplinary research program though the triangle of chemistry, electronic materials, and biomedical/biological investigations based on molecular and nano-assembled building blocks of conducting polymers. Although many applications of conducting polymers have been demonstrated feasible, there was only limited research toward biological and biomedical applications based on the non-functionalized forms of conducting polymers. Conducting polymers introduce electrical characteristics to build up the complexity necessary for further understanding of the targeted biological/biomedical issues. In our research, we utilize conductive molecular building blocks to synthesize conducting polymers tool-kits for biologoical/biomedical applications. In this talk, it will contain mainly three parts: (1) more efficient and atom-economic strategy to synthesize molecular building blocks for functional-pi materials, (2) chemical and electrochemical approaches to synthesize different nanostructured conducting polymer, and (3) utilization of nanostructured and functionalized conducting polymers for various bioengineering applications, particularly biosensing and cell engineering.

 

Title:Group 9 Metal-Catalyzed Asymmetric Arylations and Alkynylations
Speaker:Professor Takahiro Nishimura
Date:7 September 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Choon Hong
Abstract:

Recent progress of rhodium-catalyzed asymmetric addition of organoboron regents to electron-deficient alkenes provides one of the most reliable methods available for the synthesis of chiral carbonyl compounds, where a variety of aryl and alkenyl groups are introduced with high enantioselectivity. 1 Since the first report on the asymmetric addition of arylboronic acids to conjugated enones by use of a Rh/binap catalyst in 1998, 2 this type of asymmetric catalysis has been extended to the addition to a wide variety of electron deficient alkenes. In this context, we have recently developed asymmetric arylations of electron deficient alkenes, which are catalyzed by rhodium 3 and iridium 4 complexes coordinated with chiral diene ligands. In this seminar, some of the recent results will be presented. The results of the cobalt-catalyzed asymmetric alkynylation of conjugated enones or oxabenzonorbornadienes will also be presented. 5

1. For reviews, see: (a) Hayashi, T.; Yamasaki, K.; Chem. Rev. 2003, 103, 2829. (b) Christoffers, J.; Koripelly, G.; Rosiak, A.; Rössle, M. Synthesis 2007, 1279. (c) Edwards, H. J.; Hargrave, J. D.; Penrose, S. D.; Frost, C. G. Chem. Soc. Rev. 2010, 39, 2093. (d) Tian, P.; Dong, H.- Q.; Lin, G.-Q. ACS Catal. 2012, 2, 95. 2. Takaya, Y.; Ogasawara, M.; Hayashi, T.; Sakai, M.; Miyaura, N. J. Am. Chem. Soc. 1998, 120, 5579. 3. (a) Asymmetric Synthesis of (Triaryl)methylamines by Rhodium-Catalyzed Addition of Arylboroxines to Cyclic N-Sulfonyl Ketimines, Nishimura, T.; Noishiki, A.; Tsui, G. C.; Hayashi, T. J. Am. Chem. Soc. 2012, 134, 5056. (b) Rhodium/chiral diene-catalyzed asymmetric methylation of N-sulfonylarylimines with trimethylboroxine, Nishimura, T.; Ashouri, A.; Ebe, Y.; Maeda, Y.; Hayashi, T. Tetrahedron: Asymmetry 2012, 23, 655. (c) Effect of Chiral Diene Ligands in Rhodium-Catalyzed Asymmetric Addition of Arylboronic Acids to α,βUnsaturated Sulfonyl Compounds, Nishimura, T.; Takiguchi, Y.; Hayashi, T. J. Am. Chem. Soc. 2012, 134, 9086. 4. (a) Iridium/Chiral Diene-Catalyzed Asymmetric 1,6-Addition of Arylboroxines to α,β,γ,δ-Unsaturated Carbonyl Compounds. Nishimura, T.; Yasuhara, Y.; Sawano, T.; Hayashi, T. J. Am. Chem. Soc. 2010, 132, 7872. (b) Electronic tuning of chiral diene ligands in iridium-catalyzed asymmetric 1,6-addition of arylboroxines to δ-aryl-α,β,γ,δ-unsaturated ketones. Nishimura, T.; Noishiki, A.; Hayashi, T. Chem. Commun. 2012, 48, 973. 5. (a) Cobalt-catalyzed conjugate addition of silylacetylenes to α,β-unsaturated ketones. Nishimura, T.; Sawano, T.; Ou, K.; Hayashi, T. Chem. Commun. 2011, 47, 10142. (b) Cobalt-catalyzed asymmetric addition of silylacetylenes to oxa- and azabenzonorbornadienes, Sawano, T.; Oh, K.; Nishimura, T.; Hayashi, T. Chem. Commun. 2012, 48, 6106.

 

Title:Properties of Molecules and Nanoparticles in Complex Environments
Speaker:Professor Hans Ågren
Date:31 August 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract:

In this talk I will briefly review some ongoing research at our department. I will highlight recent efforts using the integrated quantum mechanics - molecular dynamics approach developed to predict various properties of molecules in solution and complex environments [1-5]. Some results will be discussed on solvatochromatic effects, one- and two-photon absorption for solvent, protein and DNA environments [6], and probe molecule - amyloid fibril complexes. I will also discuss work on nanoparticles, like colloidal quantum dots and upconversion rearearth nanocrystals, where we combine modelling with experimental measurements for solar cell and bioimaging applications [7-12]

[1] C.B. Nielsen, O. Christiansen, K.V. Mikkelsen, J. Kongsted, J. Chem. Phys., 126, 154112 (2007). [2] N.A. Murugan, J. Kongsted, Z. Rinkevicius, and H. Agren, Proc. Acad. Nat. Science (USA), 107, 16453 (2010). [3] N. A. Murugan, J. Kongsted, Z. Rinkevicius, K. Aidas, and H. Agren, J. Phys. Chem. B, 114, 13349(2010) [4] N.A. Murugan, J. Kongsted, Z. Rinkevicius, H. Agren, Phys. Chem. Chem. Phys. 13, 1290 (2011). [5] N.A. Murugan, J. Kongsted, Z. Rinkevicius, K. Aidas, K. Mikkelsen, and H. Agren, Phys. Chem. Chem. Phys. 13, 12506 (2011). [6] N.A. Murugan, J. Kongsted, Z. Rinkevicius and H. Agren, Phys. Chem. Chem. Phys., vol. 14, pp. 1107-1112 (2012). [7] Z. Ning, H. Tian, H. Qin, Q. Zhang, H. Ågren, L. Sun, and Y. Fu, J. Phys. Chem. C, 114, 15184. (2010) [8] Z. Ning, H. Tian, C. Yuan, Y. Fu, H. Qin, Y. Fu, H. Ågren, Chem. Commun., , 47, 1536. (2011) [9] Z. Ning, H. Tian, C. Yuan, Y. Fu, H. Qin, Licheng Sun, H. Ågren, Submitted to J Mater. Chem. [10] Z. Ning, M. Molnár, et al., Phys. Chem. Chem. Phys., 13, 5848. (2011) [11] M. Molnár, Z. Ning, et al., Sensors and Actuators B: Chemical., DOI:10.1016/j.snb.2011.01.055. (2011) [12] Z. Ning, H. Tian, C. Yuan, Y. Fu, L. Sun, H. Ågren, Chem. Eur. J. 2011, DOI: 10.1002/ chem.201003527.

 

 

Title:Highly Efficient Methodologies via Nitrogenation and Dioxygen Activation
Speaker:Professor Jiao Ning
Date:8 August 2012
Time:11:00am – 12:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Choon Hong
Abstract:

On the behalf of green and sustainable chemistry, molecular oxygen is an ideal oxidant and offers attractive academic and industrial prospects. On the other hand, the development of novel methods for the preparation of nitrogen-containing molecules has been of longstanding interest to organic chemists due to their great importance in chemistry and biology. In this seminar, I would like to introduce our recent works on the aerobic oxidation reactions and oxygenations via dioxygen activation, as well as some direct transformations to nitrogen-containing molecules by direct nitrogenation at mild conditions through oxidative C-H and C-C bond cleavage strategies using NaN3 , TMSN3 , or DMF as the nitrogen source.

 

Title:Challenges in Organic Chemistry: Direct Transformation of Inert C-X Bonds
Speaker:Professor Zhang-Jie Shi
Date:8 August 2012
Time:10:00am – 11:00am
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Choon Hong
Abstract:

Our researches were focused on the development of efficient and economic synthetic methodologies as well as understanding the intrinsic properties of the inert bonds to meet the requirement of green and sustainable development.

Due to their easily availability and inert reactivity, direct application of O-containing fine chemicals is highly appealed but challenging. Our first aim is to investigate the reactivity of C-O bonds to understand their intrinsic feature as well as make them potentially applicable in synthesis. We first performed direct methylation of aryl-sp2 and benzyl sp3 C-O bonds with MeMgX in high efficiency. By altering the phosphine ligand, these two kinds of C-O bonds could be differentiated and functionalized stepwise. With this developed system, Suzukitype coupling was subsequently investigated and succeeded in the presence of EtMgBr. Later on, We first developed various cross couplings with organoboronic, organozinc and Grignard reagents based on C-O activation of aryl/akenyl carboxylates via Ni or Fe catalysis. These studies were highlighted as “a possible breakthrough” at Angew Chem. Moreover, cross couplings were also developed directly between phenolates and Grignard reagents or organoboronic reagents, which showed great potential for direct application of phenol in cross couplings. These results not only offered new strategies to construct useful motifs, but also opened new windows for understanding the features of inert C-O bonds.

C-H activation is a hot topic in chemistry community, which offers green and sustainable methodologies to construct the diverse organic molecules. In our studies, directing group oriented strategy was first considered to approach regioselective C-H activation and further substrate scopes were extended to heterocylces and general arenes. Starting from C-Hs, highly selective halogenations, Suzuki-type coupling, Hiyama-type Coupling, Kumada-type Coupling, Tsuji-Trost-type alkylation, and even Cross Dehydrogenative Arylation (CDA) from two arenes were developed. Later on, benzylic and allylic C-H Activation was also conducted to construct C-C bonds. In the aspect of developing catalytic systems, we have developed the late and noble transition metal catalysis (Pd, Ir, etc), normal transition metal catalysis (Co, Fe, Nb, Mo, etc) and even transition-metal free process for direct C-H transformations. Very recently, we have reported the first successful example to approach the direct addition of aryl C-H to C=O/N as the Grignard reagent surrogates.

Keywords: Activation, C-H Bond, C-O Bond, Catalysis

 

Title:Design of metallic nanoparticles for advanced optical applications
Speaker:Professor Timothée Toury
Date:7 August 2012
Time:2:00pm – 3:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Tan Howe Siang
Abstract:

Our research focuses on the development of metallic particles of 150 nm of typical size. These particles (gold mainly) are made by electrons beam nanolithography. We are interested in various aspects : fundamental studies and applications, on theoretical and experimental parts. Some of these aspects will be presented : 1. We use them to develop highly sensitive surfaces for SERS and SEIRA-based sensors of chemicals (traces of pollutants) or biological species (proteins). Examples of improvement for technology transfer will be presented (non polarization sensitivity for usability, mechanical robustness and higher optical sensitivity, two frequencies resonances nanostructure patterns suggested for better specificity). 2. We have engineered new shapes of these metallic nanoparticles which symmetry properties permit an efficient second harmonic generation, following a strategy that have been previously applied to molecular systems. In particular gold nanostars and goldsilver nanocylinders, which form respectively a three-fold symmetry and an asymetric 1D structure such as in a molecular diode, exhibit a significant SHG efficiency. 3. Their size is intermediate between nano and bulk, so one cannot consider them smaller than the wavelength. The structure of the modes inside the nanoparticle is then usefull to understand its optical properties. We are adapting an irreducible tensors formalism for the description of these modes to define an unequivocal language for light-matter interaction with these nanoparticles.

 

Title:Recent Studies on the Total Synthesis of Natural Products and Related Systems
Speaker:Professor Martin Banwell
Date:7 August 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract:

A diverse range of biologically active natural products is being targeted for synthesis in our laboratories. The motivations for undertaking such work are three-fold: (i) to develop structure-activity relationship (SAR) profiles for the relevant class, (ii), to develop new synthetic methodologies and, (iii), sometimes to establish the true structure of the natural product.1 Of course, such pursuits can become all the more fascinating when completely unexpected processes are uncovered. In this presentation, I will provide examples of all of these possibilities.

References: M. G. Banwell, Tetrahedron, 2008, 64, 4669

 

Title:Design of metallic nanoparticles for advanced optical applications
Speaker:Professor Timothée Toury
Date:7 August 2012
Time:2:00pm – 3:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Tan Howe Siang
Abstract:

Our research focuses on the development of metallic particles of 150 nm of typical size. These particles (gold mainly) are made by electrons beam nanolithography. We are interested in various aspects : fundamental studies and applications, on theoretical and experimental parts. Some of these aspects will be presented : 1. We use them to develop highly sensitive surfaces for SERS and SEIRA-based sensors of chemicals (traces of pollutants) or biological species (proteins). Examples of improvement for technology transfer will be presented (non polarization sensitivity for usability, mechanical robustness and higher optical sensitivity, two frequencies resonances nanostructure patterns suggested for better specificity). 2. We have engineered new shapes of these metallic nanoparticles which symmetry properties permit an efficient second harmonic generation, following a strategy that have been previously applied to molecular systems. In particular gold nanostars and goldsilver nanocylinders, which form respectively a three-fold symmetry and an asymetric 1D structure such as in a molecular diode, exhibit a significant SHG efficiency. 3. Their size is intermediate between nano and bulk, so one cannot consider them smaller than the wavelength. The structure of the modes inside the nanoparticle is then usefull to understand its optical properties. We are adapting an irreducible tensors formalism for the description of these modes to define an unequivocal language for light-matter interaction with these nanoparticles.

 

Title:Development of Catalytic Asymmetric Dearomatization Reactions
Speaker:Professor Shuli You
Date:3 August 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract:

Asymmetric dearomatization reactions are particularly attractive methods in organic synthesis given the facts that the starting materials arenes are highly abundant and readily available, and the dearomatization reaction would provide direct access to compounds bearing quaternary carbon center, or polycylces and spirocycles. Unfortunately, due to the extra stability of “aromaticity” of the arenes, their dearomatization reaction with good enantioselective control has been rarely studied. In this talk, the progress from the You laboratory on the development of catalytic asymmetric dearomatization processes will be introduced. Direct asymmetric dearomatization reactions of indoles, pyrroles, and phenols were realized with a proper choice of catalysts.

 

Title:Recent Progress in Greener Olefin Synthesis by NHC-NiH
Speaker:Professor Jason Ho Chun-Yu
Date:2 August 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract:

Alkenes are the key primary chemicals for the preparation of classes of compounds and materials. Recent advances showed that various Nheterocyclic carbene ligands have distinguish electronic and steric properties, and the combinations of Ni-NHCs are particularly attractive as compared with Pd & P ligands in the alkene syntheses and bi-functionalization with remarkable selectivity. In this talk, we wish to share our recent findings in developing new methodologies by using the NHC-Ni combination. This included: 1) a tailto-tail cross-hydroalkenylation of vinylarenes and alpha-olefins, and 2) a new tool that might effectively shuffle off the classic -Si elimination and allow subsequent catalytic C-C bond formation.

 

Title:Chiral Counterion Pair Catalysis: From Concepts to Applications
Speaker:Professor Magnus Rueping
Date:2 August 2012
Time:4:00pm – 5:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Steve Zhou
Abstract:

The development and application of metal-free catalysts has become an important topic in organic synthesis and catalysis. Recently, chiral Brønsted acids and Lewis bases have been shown to be vital alternatives to metal catalysts and examples of highly enantioselective transformations have been reported. These reactions, similar to several enzymatic processes, proceed through ion-pair and hydrogen-bond activation or through intermediary formed covalent bonds. In this presentation our introduction to enantioselective Brønsted acid and Lewis base catalysis will be shown and new and valuable transformations based on chiral ion pair concept and activation will be highlighted; including the development of enantioselective reductions, new cascade and domino reactions, asymmetric carbonyl activations as well as the concept of co-operative metal and Brønsted acid catalysis. Additionally, efforts to delineate the general requirements for performing asymmetric Brønsted acid and Lewis base catalysis as well as the applicability of these catalytic processes to the synthesis of heterocycles and natural products will be outlined.

 

Title:Time-Dependent Density-Functional Theory for Open Systems
Speaker:Professor Chen Guanhua
Date:2 August 2012
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Dr Hajime Hirao
Abstract:

First-principles methods have been limited to the isolated systems. It would thus be a good idea to extend them to the open systems where the number of electrons and energy are no longer conserved. We have proven that the electron density function of a subsystem determines uniquely the electron density or electronic properties of the entire system, which is the so-called Holographic Electron Density Theorem. Based on this, a rigorous first-principles method is sought for the open system, and it needs the electron density of the system of interest. A single-particle Liouville-von Neumann equation is proposed and developed for such a theory, and has been used to simulate from firstprinciples the transient current through electronic devices.

 

Title:The colourful chemistry of zwitterionic quinonoid ligands and their metal complexes
Speaker:Professor Pierre Braunstein
Date:1 August 2012
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Francois Mathey
Abstract:

Functional ligands combining chemically different donor atoms within the same molecule are of considerable current interest owing to their implication in a number of chemical or physical processes.1 A recently discovered class of quinonoid zwitterions provides new insights into the synthesis and properties of quinonoid molecules and their use in coordination chemistry, organometallic chemistry and homogeneous catalysis.2 Furthermore, these zwitterions afford new types of self-assembled molecular films which offer interesting possibilities for engineering metal−organic interfaces, of critical importance for organic electronics.3

1 P. Braunstein, F. Naud, Angew. Chem. Int. Ed. 2001, 40, 680; C. S. Slone, D. A. Weinberger, C. A. Mirkin, Prog. Inorg. Chem. 1999, 48, 233; A. Bader, E. Lindner, Coord. Chem. Rev. 1991, 108, 27, and references cited therein.

2 see e.g. : P. Braunstein, O. Siri, J.-P. Taquet, M.-M. Rohmer, M. Bénard, R. Welter, J. Am. Chem. Soc. 2003, 125,12246; P. Braunstein, O. Siri, J.-P. Taquet, Q.-Z. Yang, Angew. Chem., Int. Ed. 2006, 45, 1393; P. Braunstein, O. Siri, J.-P. Taquet, Q.-Z. Yang. Angew. Chem. Int. Ed. 2006, 45, 1393; Q.-Z. Yang, A. Kermagoret, M. Agostinho, O. Siri, P. Braunstein. Organometallics, 2006, 25, 5518; J.-P. Taquet, O. Siri, P. Braunstein, R. Welter, Inorg. Chem. 2006, 45, 4668; O. Siri, J.-P. Taquet, J.-P. Collin, M.-M. Rohmer, M. Bénard, P. Braunstein, Chem. Eur. J. 2005, 11, 7247; Q.-Z. Yang, O. Siri, P. Braunstein, Chem. Commun. 2005, 2660.

3 J. Xiao, Z. Zhang, D. Wu, L. Routaboul, P. Braunstein, B. Doudin, Y. B. Losovyj, O. Kizilkaya, L. G. Rosa, C. N. Borca, A. Gruverman, P. A. Dowben, Phys. Chem. Chem. Phys. 2010, 12, 10329−10340 ; L. Routaboul, P. Braunstein, J. Xiao, Z. Zhang, P. A. Dowben, G. Dalmas, V. Da Costa, O. Feĺix, G. Decher, L. G. Rosa, B. Doudin, J. Am. Chem. Soc. 2012, 134, 8494; D. A. Kunkel, S. Simpson, J. Nitz, G. A. Rojas, E. Zurek, L. Routaboul, B. Doudin, P. Braunstein, P. A. Dowben, A. Enders, Chem. Commun., 2012, 48, 7143.

 

 

Title:A Highly anti-Selective Asymmetric Henry Reaction Catalyzed by Chiral Copper Complex
Speaker:Professor Wang Zhiyong
Date:1 August 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng 
Abstract:

 

The catalytic asymmetric nitroaldol reaction provides a facile method to generate the enantiomerically enriched β-amino alcohols by reducing the nitro group, which is an important structural motif in natural and designed compounds with interesting biological properties.1 Since the Shibasaki group reported the first catalytic asymmetric nitroaldol reaction,2 tremendous efforts have been made to develop catalytic asymmetric Henry reaction.3 As optically active anti amino alcohols are versatile building blocks of many natural products,8 we recently focused our research on the efficient catalytic systems for highly anti-selective Henry reaction. A highly anti-selective asymmetric Henry reaction has been developed, affording the synthetic versatile β-nitroalcohols in a predominately anti-selective manner (mostly above 15:1) and excellent ee values (mostly above 95%). Moreover, the anti-selective Henry reaction was carried out in water for the first time in up to 99% ee. The catalytic mechanism was proposed on the detection of the intermediates by extractive electrospray ionization mass spectrometry (EESI-MS). Furthermore, the anti-adducts were successfully transformed into biochemically important (+)-spisulosine and a pyrroloisoquinoline derivative.

Reference (1) Sasai, H.; Suzuki, T.; Arai, S.; Arai, T.; Shibasaki, M. J. Am. Chem. Soc. 1992, 114, 4418-4420 (2) (a) Uraguchi, D.; Sakaki, S.; Ooi, T. J. Am. Chem. Soc. 2007, 129, 12392-12393. (b) Uraguchi, D.; Nakamura, S.; Ooi, T. Angew. Chem., Int. Ed. 2010, 49, 7562-7565. (3) Lai, G. Y.; Guo, F. F.; Zheng, Y. Q.; Fang, Y.; Song, H. G.; Xu, K.; Wang, S. J.; Zha, Z. G.; Wang, Z. Y. Chem. Eur. J. 2011, 17, 1114-1117.

 

Title:Nano-materials, an efficient and promising family of novel heterogeneous catalyst in organic synthesis
Speaker:Professor Wang Zhiyong
Date:1 August 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng 
Abstract:

Nano materials with high surface areas as well as reactive morphologies have been widely studied. Recently nano-metals or nano-metal oxides were extensively employed as the heterogeneous catalyst to different organic reactions. Nano-material catalyzed reactions are generally characterized by easy purification of products, efficient recycling of catalyst and minimization of metal traces in the products. We have been focusing on this research for several years. Herein we report our research results about different preparation of the heterogeneous catalysts based on the different nano-materials and their application in various organic reactions.

Reference: 1. Angew.Chem.Int.Ed., 2011, 50, 8917 2. Adv. Synth. Catal. 2012, 354, 569 3. Chem. Commun., 2010, 46, 5244 4. Dalton. Trans, 2009, 43, 9363

 

Title:Solid-Liquid Interface Photo-Electrochemical Catalysis From First Principles
Speaker:Professor Zhi-Pan Liu
Date:27 July 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Chen Hongyu
Abstract:

In this talk, I will give a short review on theoretical progress on catalysis and present our recent results in understanding solid-liquid interface catalysis [1-4]. Methodologically, we developed a periodic continuum solvation model based on the modified-Poisson-Boltzmann equation within the periodic DFT slab framework, which is designed for studying complex catalytic reactions at the solid-liquid reactions under the influence of electrochemical potentials, surface charges and solution [3,4]. Using the approach, we investigated water oxidation on RuO2 surface and oxygen reduction on Pt surface, and calculated Tafel kinetics quantitatively. We show that the elementary electrocatalytic reactions on surface can be classified into two general classes according to their redox properties, whose activity exhibits distinct potential dependence. Our approach has also been utilized to investigate some other catalytic reactions on nanoparticles in aqueous surroundings [1,2].

References 1) Li, Y.-F.; Liu, Z.-P.* “Particle Size, Shape and Activity for Photocatalysis on Titania Anatase Nanoparticles in Aqueous Surroundings” , J. Am. Chem. Soc. 2011, 133,15743 2) Shang, C.; Liu, Z.-P.* “Origin and Activity of Gold Nanoparticle as Aerobic Oxidation Catalyst in Aqueous Solution” J. Am. Chem. Soc. 2011, 133,9938 3) Fang, Y.-H.; Liu, Z.-P.* “Mechanism and Tafel Lines of Electro-oxidation of Water to Oxygen on RuO2(110) ”, J. Am. Chem. Soc. 2010, 132, 18214 4) Li, Y.-F.; Liu, Z.-P.*; Liu, L.;Gao, W. “Mechanism and Activity of Photocatalytic Oxygen Evolution on Titania Anatase in Aqueous Surroundings ”, J. Am. Chem. Soc. 2010, 132, 13008

 

Title:Synthesis, the unfashionable and the infamous
Speaker:Professor Michael Sherburn
Date:23 July 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Philip Chan
Abstract:

It is not easy to think of a field of synthetic chemistry that is less popular than fundamental hydrocarbon chemistry. It is also hard to imagine a group of structures with a greater reputation for instability than the polyenes. This talk aims to convince you that fundamental hydrocarbon chemistry has significant potential for original discoveries and that at least some of your assumptions about the instability of polyenes are wrong! For many years, the dendralenes (branched oligo-alkenes) were thought to be too unstable to be synthetically useful. We demonstrated that the perception was false: we were the first to prepare the dendralenes and we did so using standard laboratory equipment. We recorded their spectroscopic, physical and chemical properties and discovered alternation in their behaviour – the first time such a property has been witnessed in a family of fundamental structures since the annulenes. We have also demonstrated that dendralenes have the unique capacity to undergo diene-transmissive cycloadditions, spectacular processes that result in many new bonds being forged in a single operation. This presentation will demonstrate that the dendralenes represent the tip of the iceberg when it comes to as yet un-prepared hydrocarbons with huge synthetic potential. We will reveal new discoveries and efficient synthetic applications involving these unfashionable and infamous structures.

 

Title:Inorganic Nanomaterials: Functional Scaffold in Therapeutics and Diagnostics
Speaker:Dr Monty Liong
Date:20 July 2012
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract:

The past decade has shown tremendous advances in the synthesis of inorganic nanomaterials with precisely controlled structures and properties. If we can engineer these nanomaterials to sensitively diagnose cancer and infectious diseases, it will provide critical information for stratifying patients and assessing treatment efficacy. Furthermore, the development of nanomaterials for drug delivery will improve the bioavailability and enhance the therapeutic efficiency. In this talk, I will describe my research efforts in functional inorganic nanomaterials focused on 1) the synthesis of highly porous nanomaterials as versatile carrier and delivery system for biologically active molecules, and 2) the development of signal amplification in magnetic resonance assay for molecular diagnostics. These efforts are specifically designed to address two issues: How can we provide relevant clinical diagnoses using limited sample specimen and minimal purification? How can we enhance the therapeutic efficacy to eliminate the disease, but minimize the damage to healthy tissues? Combining these methods with current technology can potentially resolve current diagnostic and therapeutic challenges in oncology and global health.

 

Title:Developing Nanoprobes Towards Clinical Translation
Speaker:Professor Zhen Cheng
Date:13 July 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Xing Bengang
Abstract:

Molecular probe development is an important component in cancer molecular imaging. A wide variety of molecular platforms including small molecule, peptide, protein, nanoparticle, have been explored for development of novel imaging probes with desirable properties. Of these platforms, nanoparticles are particularly promising and have attracted many research efforts because of their unique and many favorable features. In this presentation, our recent progress on developing clinical translatable nanoprobes will be presented. These nanoprobes include novel quantum dots, iron oxide and gold nanoparticles for cancer multimodality imaging (optical imaging, MRI, photoacoustic imaging, etc.).

Title:Nanomaterials for electronic, optical, and optoelectronic applications
Speaker:Professor Cornelis van Walree
Date:12 July 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Philip Chan
Abstract:

In my seminar I will address the synthesis, characterization and functioning of nanomaterials for electronic, optical, and optoelectronic applications. These nanomaterials on one hand feature σ-π conjugated oligo(cyclohexylidenes) and their end-functionalized derivatives, compounds of type 1. In these partly unsaturated hydrocarbons the π-bonds interact with each other via the σ-orbitals. It will be shown that this alternative mode of conjugation forms the basis for attractive electronic and optoelectronic properties. In particular photoinduced charge separation, the use as molecular conduction wire and the formation of supramolecular assemblies (for instance with semiconductor quantum dots) are discussed.

A second topic concerns the synthesis and characterization of colloidal CaS and SrS nanocrystals. These wide band gap semiconductors can function as host for luminescent guests and as such represent biocompatible luminescent nanomaterials.

 

Title:Nitrogen Functionalization with 2-Azido-1,3-dimethylimidazolinium Salts
Speaker:Professor Mitsuru Kitamura
Date:9 July 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract:2-Azido-1,3-dimethylimidazolinium salts 1 were found to be used for various nitrogen functionalization such as amination (N1 introduction), diazo-transfer reaction (N2 introduction), and azide-transfer reaction (N3 introduction).1-5 2-Azido-1,3-dimethylimidazolinium chloride (ADMC 1a) and its corresponding hexafluorophosphate (ADMP 1b) reacted with 1,3-dicarbonyl compounds under mild basic conditions to give 2-diazo-1,3-dicarbonyl compounds in high yields, which are easily isolated because the byproducts are highly soluble in water. Naphthols also reacted with ADMC 1a to give corresponding diazonaphthoquinones (DNQ). Furthermore, ADMP 1b shows efficient diazo-transfer ability to primary amines even without the aid of a metal salt such as Cu(II). Using this diazotization approach, various alkyl/aryl azides were obtained directly from corresponding primary amines. In addition, 2-azido-1,3- dimethylimidazolinium salts 1 were found to be employed as azide-transfer, and amination reagents. In the presentation, synthetic utility of DNQ will be also discussed. 1. M. Kitamura, N. Tashiro, T. Okauchi, Synlett 2009, 2943. M. Kitamura, N. Tashiro, S. Miyagawa, T. Okauchi, Synthesis 2011, 1037. 2. M. Kitamura, N. Tashiro, R. Sakata, T. Okauchi, T. Synlett 2010, 2503. 3. M. Kitamura, M. Yano, N. Tashiro, S. Miyagawa, M. Sando, T. Okauchi, Eur. J. Org. Chem. 2011, 458. 4. M. Kitamura, N. Tashiro, Y. Takamoto, T. Okauchi, Chem. Lett. 2010, 39, 732. 5. M. Kitamura, T. Koga, M. Yano, T. Okauchi, Synlett 2012 in press. 6. M. Kitamura, S. Miyagawa, T. Okauchi, Tetrahedron Lett. 2011, 52, 3158.

 

Title:Engineering Bottom-up Protein Assembly at Nanoscale: Towards High Density, High Payload, Quantifiable Protein Arrays
Speaker:Dr Jong-in Hahm
Date:4 July 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Ling Xing Yi
Abstract: 

This talk presents an overview of our on-going nanobio research, aiming to provide fundamental understanding on nanoscale protein adsorption behavior and to develop more advanced, next-generation protein arrays. Specifically, we evaluate protein adsorption characteristics on chemically homogeneous and heterogeneous polymeric surfaces by employing diblock copolymers, homopolymers, and polymer blends as protein templates. We also investigate distance-dependent protein adsorption behavior on the interfacial region between the two blocks in the diblock and blend films. We carry out for the first time quantitative activity measurements of various enzymes immobilized selectively on one of the domains in microphase-separated block copolymer films. The exact number of adsorbed proteins on diblock copolymer surfaces is determined by measuring the size of the individual protein and the repeat spacing of the underlying polymeric nanodomain. The specific activity of enzymes adsorbed on the diblock copolymer surface can thus be measured and compared quantitatively to that of enzymes in free solution. Protein assembly on chemically modified polymeric nanotemplates is also explored in order to demonstrate the versatility of our new methods in providing a wide range of template size and shape. This approach will be particularly beneficial for fabricating periodic patterns of proteins on surfaces with a nanometer spacing without the use of lithographic techniques based on electron beam or extreme UV. Our results demonstrate that a wide range of self-assembling, chemically heterogeneous, nanoscale domains in diblock copolymers can be used as basis for high payload, high density protein templates. Subsequently, the resulting protein nanoarrays can serve as novel, high density, high payload, biologically functional substrates in many proteomics applications

 

Title:Cell Perturbation by Nanoparticles and Its Regulations
Speaker:Professor Yan Bing
Date:3 July 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Liu Xuewei
Abstract: 

Nanomaterials are widely used in various industrial sectors, biomedicine, and more than 1300 consumer products. Although there is still no safety regulation, their potential toxicity is a major concern worldwide. We discovered that carbon nanotubes enter human cells1 , perturb cellular signaling pathways2 , affect various cell functions, and cause malfunctions in animals3 . Because the majority of atoms in a nano-sized particle are on the surface, chemistry modification on its surface may change its biological properties significantly. To prove this hypothesis, we modified nanoparticle surface using a nano-combinatorial chemistry approach4 . Novel nanoparticles were discovered to have a reduced toxicity, an enhanced cancer targeting ability5 , or an increased cell differentiation regulation. Quantitative nanostructure-activity relationships (QNAR) models have been built and validated using a dataset of 84 CNTs decorated with organic surface modifiers and tested in different biocompatibility and toxicological assay. These QNAR models have been applied for virtual screening of a library collection of 240,000 ligands potentially attachable to CNT. As a proof of concept, putatively toxic and nontoxic CNTs surface-decorated by the selected ligands priortized by QNAR model-based virtual screening were synthesized and tested. An 85% success rate was achieved. This opens new perspectives concerning the rational design of nanoparticles with controlled biological effects.

1. Mu QX, Broughton DL, Yan B. Endosomal leakage and Nuclear Translocation of Multiwalled Carbon Nanotubes: Developing a Model for Cell Uptake. Nano Letters 2009, 9(12), 4370-4375. 2. Mu, Q.X., Du, G.Q., Chen, T.S., Zhang, B., Yan, B. Suppression of Human Bone Mophorgenetic Protein (BMP) Signaling by Carboxylated Single-Walled Carbon Nanotubes. ACS Nano 2009, 3, (5), 1139-1144. 3. Bai YH, Zhang Y, Zhang JP, Mu QX, Zhang WD, Butch E, Snyder S, Yan B. Repeated carbon nanotube administrations in male mice cause reversible testis damage without affecting fertility. Nature Nanotechnology, 2010, 5(9), 683-689. 4. Zhou, H.; Mu, Q.; Gao, N.; Liu, A.; Xing, Y.; Gao, S.; Zhang, Q.; Qu, G.; Chen, Y.; Liu, G.; Zhang, B.; Yan. B. A Nano-Combinatorial Library Strategy for the Discovery of Nanotubes with Reduced Protein-Binding, Cytotoxicity, and Immune Response, Nano Lett. 2008, 8 (3), 859-865. 5. Zhou,H., Jiao, P, Yang,L., Li,X., Yan, B. Enhancing Cell Recognition by Scrutinizing Cell Surfaces with a Nanoparticle Array. J. Am. Chem. Soc. 2010, 133(4), 680-682.


 

Title:Bioactive Heterocyclic Compounds Methods and Strategies
Speaker:Professor Janine Cossy
Date:29 June 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract: 

Complex biologically active molecules are a good source of inspiration to develop methods and one major challenge, in synthetic organic chemistry, is the design and execution of concise approaches to these molecules. Strategies that are using reactions that rapidly lead to the skeleton framework of natural and/or biologically active heterocycles are attractive. In this context, we have explored the construction of heterocycles using catalytic reactions involving organometallics to induce diastereoselective coupling reactions and cyclizations. These methods and their applications to the synthesis of biologically active complex natural and non-natural products will be presented.

 

Title:Water-Oxidation Catalysts for Solar Fuel Production
Speaker:Professor Gary Brudvig
Date:14 June 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Chen Hongyu
Abstract: 

Devising cost effective methods for efficiently capturing and storing solar energy is among the grand challenges of science.[1] In order to use visible light to drive water-oxidation catalysis, we have designed high-potential photosensitizers for functionalization of metal oxide surfaces. In these constructs, the photosensitizer efficiently absorbs visible light and uses the energy to initiate electron transfer to an attached metal oxide. The injected electrons can ultimately be used for H2 production at a cathode while the resulting holes (sensitizer radical cations) provi de the potential needed for a water-oxidation catalyst. We have prepared photoanodes consisting of high-potential free-base and zinc bis-pe ntafluorophenyl porphyrin sensitizers (PF10 and ZnPF10) bearing linkers for functionalization of TiO2 and SnO2 nanoparticles. THz studies and p hotoelectrochemical measurements demonstrate that photoexcited PF10 (PF10*) is capable of injecting electrons into the SnO2 conduction ba nd (CB). In addition, the zinc derivative forms a photoinduced charge separated state on both TiO2 and SnO2 . Co-deposition of the photoano de with a molecular water-oxidation catalyst (IrCp*)[2] results in a marked increase in the observed photocurrent, consistent with light-induce d activation of the catalyst (Figure 1).[3]

[1] Directing Matter and Energy: Five Challenges for Science and the Imagination, U.S. Department of Energy, Washington, DC, December 2007. [2] J. F. Hull, D. Balcells, J. D. Blakemore, C. D. Incarvito, O. Eisenstein, G. W. Brudvig and R. H. Crabtree J. Am. Chem. Soc. 2009, 131, 8730–8731. [3] G. F. Moore, S. J. Konezny, H. -e. Song, R. L. Milot, J. D. Blakemore, M. L. Lee, V. S. Batista, C. A. Schmuttenmaer, R. H. Crabtree and G. W. Brudvig J. Phys. Chem. C 2012, 116, 4892–4902.

 

Title:Beyond Molecules: from Molecular Assembly to Supramolecular Materials
Speaker:Professor Myongsoo Lee
Date:7 June 2012
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract: 

A major challenging task in supramolecular chemistry is the design of simple molecular components that are capable of organizing into controlled molecular assembly, the essence of which is self-assembly through various types of intermolecular interactions. Along this line, we have explored small rigid-flexible block molecules to create novel self-assembling systems, including controlled self-assembled structures, switchable aggregates, and biocompatible dynamic structures (Figure). Here we will present some of related achievements in our recent study.

References 1) Z. Haung, H. Lee, S-K. Kang, J.-M. Nam, M. Lee, Nature Commun., 2011, 2, 459. 2) H.-J. Kim, T. Kim, M. Lee, Acc. Chem. Res., 2011, 44, 72. 3) H.-J. Kim, S.-K. Kang, Y.-K. Lee, C. Seok, J.-K. Lee, W.-C. Zin, M. Lee, Angew. Chem. Int. Ed., 2010, 139, 8471. 4) E. Lee, J.-K. Kim, M. Lee, J. Am. Chem. Soc., 2009, 131, 18242. 5) Y.-b. Lim, K.-S. Moon and M. Lee, Chem. Soc. Rev., 2009, 38, 925. 6) J.-K. Kim, E. Lee, Y.-b. Lim, M. Lee, Angew. Chem. Int. Ed., 2008, 47, 4662.

 

Title:Development of New Catalysts for Organic Synthesis
Speaker:Professor Atsushi Nishida
Date:5 June 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Naohiko Yoshikai
Abstract: 

Part I; Reusable Iridium Catalyst for C-H Borylation

Arylboronates are synthetic intermediates that are used in the synthesis of drugs and functional materials. Among the methods used for their preparation, C-H borylation is one of the most promising because it has high atom efficiency and can be conducted under milder reaction conditions. Recently, we reported the preparation of a recyclable iridium catalyst for the C-H borylation reaction.1) The iridium catalyst, which can be prepared from an iridium precursor, 2,2’-bipyridine-4,4’-dicarboxylic acid (BPDCA) and bis(pinacolato)diboron, could be reused at least ten times in the borylation of benzene. In this lecture, I will discuss the first continuousflow C-H borylation system using our new recyclable catalyst.2)

Part II; Asymmetric Diels-Alder Reaction Using Danishefsky Diene           

Methoxy-3-trimethylsiloxy-1, 3-butadiene (Danishefsky’s diene) is recognized as a synthetically useful diene due to its high reactivity in the Diels-Alder reaction with electron-deficient alkenes to give substituted cyclohexenes and cyclohexenones. However, the development of catalytic enantioselective versions of Diels-Alder reactions using Danishefsky’s-type dienes with electron-deficient alkenes has been a difficult issue because of the instability of the dienes under Lewis acidic conditions. We have been developed a new chiral ligand, BINAMIDE and BINUREA which are easily prepared from 1,1’-binaphtyl-2, 2’-diamine. The highly diastereo- and enantioselective Diels-Alder reaction of Danishefsky’s-type dienes with electron-deficient alkenes in the presence of Yb(III)-BINAMIDE (or BINUREA) complex has been developed. The reaction proceeded exo-selective mode and gave chiral highly functionalized cyclohexene derivatives in good yields. 3, 4) An asymmetric total synthesis of natural (–)-platyphyllide will be discussed. 5)

1) Tetrahedron Lett. 2009, 50, 6176-6179. 2) Adv. Synth. Cat. 2010, 352, 1662-1666. 3) J. Am. Chem. Soc., 2008, 125, 7484-7485. 4) Tetrahedron Lett. 2009, 50, 5652-5655. 5) J. Org. Chem. 2010, 75, 3871-3874.

 

Title:Technology Assisted Synthesis of Biomedical Imaging Agents
Speaker:Professor Graham Jones
Date:4 June 2012
Time:2:00pm – 3:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract: 

Advances in flow and microwave technology have greatly accelerated discovery chemistry through optimization of syntheses and affording access to intermediates inaccessible via conventional methodologies. One aspect of current interest is the preparation of radiolabeled agents for subsequent application to in vivo SPECT and PET imaging in early stage preclinical screening. In this presentation we will firstly highlight a three component coupling method that allows rapid assembly of fluoroalkyl, fluorovinyl and fluoroalkynylated arenes from readily available precursors. Applications in the synthesis of CNS and cardiovascular agents will be presented, together with potential for 18F labeled analogs to allow PET imaging. Flow methodology has also been applied for the radio tagging of proteins and antibodies to allow in vivo biodistribution studies to be undertaken using short and medium half-life radionuclides. In addition, flow methodologies are currently being applied to the construction of complex heterocyclic targets using a range of pericyclic and insertion reactions which will be discussed, together with future applications in the area of immobilized reagents / catalysts.

 

Title:Progresses and Difficulties the Modeling of Enzymatic Reactions
Speaker:Professor Pedro Alexandrino Fernandes
Date:29 May 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract: 

In this talk I will summarize the problems which we have been facing when we try to predict the catalytic mechanism of an enzymatic reaction. There is no obvious solution for most of them and there is no consensus about the approximations that should be made. The most important unsolved aspects are the appropriate Hamiltonian to be used, the dimension of the molecular model of the enzyme and substrate, and the extension in which the sampling of the conformational space should be carried out. The origin of the difficulties lies in the range of timescales that the enzymatic motion spans, and the long range of the interatomic interactions that act specifically to differentially stabilize the stationary species found along the potential energy surface. The approximations that we have been carrying out will be presented and discussed. Our studies in enzymes such as Ribonucleotide Reductase, beta-galactosidase and farnesyltransferanse, among others, will illustrate the concepts. A comparison with other possible solutions will also be made.

 

Title:Cationic peptides and peptide nucleic acids: Probing their entry into cells
Speaker:Professor Krishna N Ganesh
Date:14 May 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Chen Gang
Abstract: 

Peptide nucleic acids (PNA) are a class of non-ionic DNA mimics, in which the sugar-phosphate backbone is replaced by ethylenediamine-glycine backbone. They bind complementary DNA or RNA with high affinity and selectivity and hence promised to be potential therapeutic agents. However they have serious drawbacks in terms of their aqueous solubility and cell penetration ability. Their equal affinity for iso-sequential DNA / RNA also decreases their target specificity by half. In order to overcome these drawbacks, we have designed, synthesized and evaluated several PNA analogues (1-8) which are conformationally constrained, chiral and cationic. The structural variations include those having rings in backbone such as pyrrolidine, cyclopentyl and cyclohexyl moieties which are also chiral, incorporation of cationic groups to make them more soluble in water, acyclic PNA analogues such as those incorporating isoaminobutyric acid units, cationic aminomethylene side chains etc. We have recently labeled some of these with fluorescence groups to examine their cell membrane permeability properties. This lecture presents a comparison of the biophysical properties such as their differential complementation with iso-sequential DNA / RNA, selectivity in binding parallel and antiparrallel sequences and their cell permeation studies. We have recently designed cationic collagen peptides carrying guanidine function which have shown efficient cell penetration, localization in cytoplasm and efficient cell transfection properties.

 

Title:Controlling Quantum Dynamics Phenomena with Shaped Laser Pulses Acting as Photonic Reagents
Speaker:Professor Herschel Rabitz
Date:30 April 2012
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Tan Howe Siang
Abstract: 

Since the development of the laser some 40 years ago, a longstanding dream has been to utilize this special source of radiation to manipulate dynamical events at the atomic and molecular scales. Hints that this goal may become a reality began to emerge in the 1990’s, due to a confluence of concepts and technologies involving (a) control theory, (b) ultrafast laser sources, (c) laser pulse shaping techniques, and (d) fast pattern recognition algorithms. These concepts and tools have resulted in a high speed instrument configuration capable of adaptively changing the driving laser pulse shapes, approaching the performance of thousands of independent experiments in a matter of minutes. Each particular shaped laser pulse acts as a “Photonic Reagent” much as an ordinary reagent would at a molecular scale. Although a Photonic Reagent has a fleeting existence, it can leave a permanent impact. Current demonstrations have ranged from manipulating simple systems (atoms) out of the highly complex (biomolecules). In all cases, the fundamental concept is one of adaptively manipulating quantum systems. The principles involved will be discussed, along with the presentation of the state of the field.

 

Title:Structures and formation of elemental carbon species
Speaker:Professor Robert F Curl
Date:24 April 2012
Time:3:00pm – 5:30pm
Venue:NTU SPMS LT 4
Host:Assistant Professor Martin Pumera
Abstract: 

In the twenty-six years since the discovery that molecular forms of elemental carbon, the fullerenes, could be produced, a number of investigators have carried out intense searches for other forms of elemental carbon. These searches have produced a myriad of new carbon morphologies where each kind of structure requires some particular kinds of formation conditions. The structures are known, the formation conditions are known, but in most cases a microscopic understanding of how a particular set of conditions results in a certain structure is lacking. Because they are discrete molecules, the most progress in understanding their formation chemistry has been made for the cage containing systems though we are very far from a complete understanding. This talk will review many of these new structures and discuss possible formation mechanisms of some of them.

 

Title:Zebrafish as an in vivo tool for toxicology: Déjà vu
Speaker:Dr Vladimir Korzh
Date:20 April 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract: 

The increasing number and diversity of compounds in combination with high-throughput in vitro assays generates a lot of potential drugs that require additional validation prior to their use in humans. Additional screening should be done in animal models in vivo. Given some limitations of existent animal models the new species of vertebrates should be introduced for this purpose. Initially, the zebrafish (Danio rerio) has become a popular model system for the study of vertebrate development, since the embryos and larvae of this species are small, transparent and undergo rapid development outside of maternal organism, allowing in vivo analysis of their development. More recently, the zebrafish emerged as a promising model animal for analysis of toxicity of candidate drugs. This presentation will illustrate some recent developments in usage of zebrafish for studies in toxicology and biophysics.

 

Title:Zebrafish as an in vivo tool for toxicology: Déjà vu
Speaker:Dr Vladimir Korzh
Date:20 April 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract: 

The increasing number and diversity of compounds in combination with high-throughput in vitro assays generates a lot of potential drugs that require additional validation prior to their use in humans. Additional screening should be done in animal models in vivo. Given some limitations of existent animal models the new species of vertebrates should be introduced for this purpose. Initially, the zebrafish (Danio rerio) has become a popular model system for the study of vertebrate development, since the embryos and larvae of this species are small, transparent and undergo rapid development outside of maternal organism, allowing in vivo analysis of their development. More recently, the zebrafish emerged as a promising model animal for analysis of toxicity of candidate drugs. This presentation will illustrate some recent developments in usage of zebrafish for studies in toxicology and biophysics.

 

Title:Design and Utility of Chiral Carbenes for Asymmetric Umpolung
Speaker:Professor Tomislav Rovis
Date:18 April 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Robin Chi 
Abstract: 

The reversal of a functional group’s normal mode of reactivity, termed umpolung, leads to novel ways for bond formation. Nucleophilic carbenes convert aldehydes into acyl anion equivalents via the so-called Breslow intermediate. We have developed a family of chiral nucleophilic carbene catalysts to render this process asymmetric with a heavy focus on carbon-carbon bond formation, using a variety of prochiral electrophiles. Catalyst design and mechanistic investigations with an emphasis on recent developments will be discussed.

 

Title:Scalable Processes to Pharmaceutical Intermediates and APIs Using Evolved Enzymes
Speaker:Dr Steve Collier
Date:12 April 2012
Time:2:00pm – 3:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract: 

Biocatalysis has become an increasingly important tool for the process chemist, and biocatalytic reactions can be leveraged to provide products of exquisite stereopurity. The development of directed evolution technologies has played a crucial role in enabling the delivery of enzymes as green, efficient and robust catalysts at commercial scale. This presentation will discuss the basic philosophy of directed evolution and its application to a number of different targets and processes, using a diverse range of enzymes including transaminases, acyltransferases, and oxidative enzymes

 

Title:From Enyne to Small Ring
Speaker:Professor Junliang Zhang
Date:11 April 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Robin Chi Yonggui
Abstract: 

In first part, various transformations of the electron-deficient conjugated enynes with nucleophiles and eletrophiles or 1,3-dipoles have been developed under the catalysis of base and transition metals, leading a series of carbocycles, heterocycles and acyclic compounds such as 1,3- diene, 1,2-allene. In second part, the chemistry of small rings including cyclopropane and small heterocyclic rings such as epoxide and azirdines will be presented. And two strategies will be introduced to achieve the selective C-C bond cleavage of epoxides under mild conditions. A first rhodium catalyzed hetero[5+2] cycloaddition will be also presented.

 

Title:Superresolution microscopy without fluorescence
Speaker:Professor Shi-Wei Chu
Date:5 April 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Xing Bengang
Abstract: 

Optical microscopy has established itself to be an indispensible tool in research fields such as biomedicine and material science. For far-field observation, optical resolution is limited by diffraction, a barrier set by Ernst Abbe more than 100 years ago. During the past two decades, several ground-breaking methods have been demonstrated to surpass the diffraction barrier, revolutionizing the way we access the nano world. However, all previous methods are based on switching or saturation of fluorescence, and are severely limited by switching reversibility and photobleaching. In this seminar, I will present our latest achievement on first superresolution far-field imaging based on scattering, which is a universal optical phenomenon without bleaching. Our principal finding is that plasmon resonance in a nanostructure can be saturated, resulting in saturation of optical scattering. By extracting the saturated part in the focal region, along with optical field centralization due to plasmonic resonance, microscopic resolution is reduced to below 100-nm. Our result expands the horizon of superresolution imaging from fluorescence to scattering. The expected applications range from biomedical imaging, by using metallic particles as contrast agent, to the functional inspection of plasmonic nanostructures, by visualizing plasmon oscillation modes directly with far-field observation. Moreover, all imaging modalities that utilize plasmonic properties, such as apertureless near-field microscopy, will benefit from the saturation effect for further resolution enhancement. 

 

Title:Fluorescence Microscopy: A Unique Tool in Catalysis Research
Speaker:Professor Maarten Roeffaers
Date:4 April 2012
Time:2:30pm – 3:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Edwin Yeow
Abstract: 

Light microscopy is a recent addition to the toolbox for in situ study of solid catalytic materials. It combines ease of use with noninvasiveness, high sensitivity and temporal resolution.[1,2] However, due to the diffraction of light, an optical microscope has a limited spatial resolution, which is insufficient to distinguish the nano-sized domains in catalytic solids. Here we show how single catalytic turnovers yield diffraction unlimited images of working inorganic catalysts. NASCA microscopy is experimentally simple, and yields super-resolution images of catalysts. As a first case study, we investigated the Ti-MCM-41 catalyzed epoxidation of a phenylbutadienyl-substituted Bodipy probe using 35 mM tert-butylhydroperoxide.[3] The fluorescence microscope allows the selective detection of single, yellow fluorescent epoxidized Bodipy reaction products even against the overwhelming red, reagent fluorescence. A real-time movie containing multiple single epoxidation reaction events was recorded and the nanometer-accurate fitted positions of these individual events are plotted on the optical transmission image. These images clearly show that the catalytic reaction mainly occurs at the outer rim of the Ti-MCM-41 particles. In a second case study, we extended this single turnover localization technique to acid zeolite catalysed reactions.[4] Whereas single turnover studies so far have been using large polycyclic substrates which cannot enter the zeolite micropores,[1,5] this study critically depends on identifying a small reagent that is converted into a single molecule detectable fluorescent product. Surprisingly furfuryl alcohol is such a reagent (Figure left). Similarly, from these single turnover fluorescence movies a nanoscale activity map can be generated (Figure right) which allow direct identification of nanometer-scale catalytic hotspots. In this contribution we show that fluorescence microscopy allows the in situ observation of single catalytic turnovers for different types of nanoporous catalysts. This high-resolution single turnover mapping allows the direct localization of catalytic hotspots at the nanometerscale, furthermore this approach it is an excellent tool for observing the complex interplay between diffusion and reaction at the single particle level.

REFERENCES [1]M. B. J. Roeffaers, et al., Nature 2006, 439, 572. [2] G De Cremer et al., Chem. Soc.Rev. 2010, 39: 4703 [3]G. De Cremer, et al., Angew. Chem. 2010, 49, 908. [4]M. B. J. Roeffaers, et al., Angew. Chem. 2009, 48, 9285. [5]V. M. Martinez, et al., J. Am. Chem. Soc. 2008, 130, 13192.

 

Title:β-Peptides – from organic synthesis to biochemistry, biology, medicinal chemistry…and back
Speaker:Professor Dieter Seebach
Date:4 April 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Koichi Narasaka
Abstract: 

The insertion of a CH2 -group into each and every residue of a peptide with proteinogenic side chains opens a door into a new world with similarities and, at the same time, fundamental differences of structures. The journey into this world was only possible by hard-core organic syntheses. The biological tests of proteolytically, as well as metabolically stable β-peptidic mimics of a number of α-peptidic natural products and cell-permeating β-peptides will be described. The biological investigations have led to the discovery of β-peptide-cleaving enzymes, which can be used for kinetic resolutions of β-amino acids.

 

Title:Discovery and development of a new herbicide: the story of Bicyclopyrone
Speaker:Professor Ian Aspinall
Date:3 April 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Philip Chan
Abstract: 

Leptospermone (1) was isolated in 1977 from the bottle brush plant and showed herbicidal activity (HPPD symptomology) albeit at a relativity high rate (5Kg/ha). Five years later aryl triketones of type (2) were discovered by Stauffer (a Syngenta legacy company) and showed the same herbicidal symptomology as Leptospermone. Optimisation led to the commercial product Mesotrione (3) which showed very good activity on a range of broad-leaf weeds in maize. A next generation HPPD inhibitor was sought with a broader weed spectrum i.e. grasses as well as broad leaf weeds. This lead to the discovery of Bycyclopyrone (4), a new maize selective broad spectrum herbicide.

 

Title:Functional Carbon-Rich Organometallic Compounds: Theoretical Aspects
Speaker:Professor Karine Costuas
Date:30 March 2012
Time:3:00pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Chen Hongyu
Abstract: 

Molecular materials based on the assemblage of organometallic fragments and conjugated organic ligands are among the most studied compounds in coordination chemistry. This is due to their relatively good stability combined with their excited-state and redox properties which confer them interesting physical properties in several domains (magnetism, optics, electrochemistry…). These multifunctional systems are promising candidates to be incorporated in nanoscale devices for molecular electronics and/or spintronics. The control and manipulation of the interactions between the metal termini of such systems are of great practical importance, but present considerable conceptual challenges. These challenges can be met by combining experimental and theoretical studies. Using results obtained from theoretical calculations of density-functional theory (DFT) type, some physical properties of representative compounds will be discussed. Particular emphasis will be put on the electronic reasons of the changes in structural and physical properties upon oxidation or reduction, or upon structure modification of metallic moieties and of the conjugated ligands.

 

Title:Organometallic Molecular Wires and Switches with Carbon-Rich Ruthenium Units
Speaker:Professor Stéphane Rigaut
Date:30 March 2012
Time:2:00pm – 3:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Chen Hongyu
Abstract: 

Unique synergetic properties can be obtained with accurate combinations of metal complexes and functional units. Ruthenium carbon-rich complexes have been involved in the building of original redox active molecular wires and junctions, owing to the excellent ability of the system to promote a strong electronic coupling between the metal centers and the conjugated organic ligands. We are now taking advantage of the perturbation of different systems with the ruthenium moiety to reach multifunctional materials that gather efficient switching behaviors, i.e. to achieve the photo or redox modulation of properties such as absorption, luminescence, conductance, or magnetism. For example, the perturbation of a dithienylethene (DTE) system with ruthenium moieties led to a multifunctional responsive material, and the association between an ytterbium ion and a ruthenium carbon-rich complex enabled the first redox switching of the nearIR Yb(III) luminescence. These studies are supported by careful parallel experimental and theoretical investigations.

 

Title:Phosphine Catalysis and Its Applications
Speaker:Professor Ohyun Kwon
Date:28 March 2012
Time:11am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract: 

Soft nucleophilic phosphine catalysis has been known since the 1960s as a result of the pioneering work of Rauhut−Currier and Morita. In the 1990s, Trost and Lu made important discoveries based on nucleophilc phosphine catalysis and reported isomerization, umpolung addition, and [3+2] cycloaddition. Nonetheless, it was not until the 2000s that the area of nucleophilic phosphine catalysis began to flourish, with the report of numerous new reaction manifolds and asymmetric variations. My group, through careful analysis of the mechanism of the phosphine catalysis reactions, has demonstrated over a dozen new reactions facilitated under nucleophilic phosphine catalysis conditions. The results are a one‐step conversion of simple acyclic starting materials into various carbo- and heterocycles, such as tetrahydropyridines, cyclohexenes, dioxanes, pyrones, dihydropyrones, pyrrolines, bicyclic succinimides, dihydrocoumarins, cyclic nitronates, benzoxazolines, benzothiazolines, benzodioxolines, benzoxathiolines, benzodithiolines, oxazolines, thiazolines, pyrrolines, oxathiolanes, oxathianes, indolines, dihydropyrrolopyridines, benzimidazolines, dihydrobenzo-3,1-oxazines, dihydrobenzo-1,4-oxazines, tetrahydroquinolines, and tetrahydroisoquinolines. The practical values of these phosphine-catalyzed annulation processes are significant since (1) they are atomeconomic and environmentally friendly, and (2) the heterocycles are an immense class of organic compounds with numerous practical applications. To further illustrate the utility of the phosphine-catalyzed [4+2] annulation chemistry, we have been engaged in the total synthesis of indole alkaloids, completing total syntheses of alstonerine, macroline, and hirsutine. More recently, enantioselective total synthesis of (+)-ibophyllidine has been completed.

 

Title:Non Equilibrium Structured Nanomolecular Inorganic Assemblies
Speaker:Professor Lee Cronin
Date:27 March 2012
Time:11am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Li Tianhu
Abstract: 

The organization of matter across length scales, starting from well defined building blocks, is a key challenge in the design of advanced functional materials and devices. Patterned, or highly structured, assemblies can be formed spontaneously in systems which are e xposed to fluxes of matter and energy. These assemblies can sustain themselves far from equilibrium whilst the fluxes are maintained, leading to the emergence of temporal and spatial structures. In our work we opted to investigate such assemblies using polyoxometalate clusters. Such clusters are interesting since their assembly can bridge multiple length scales from the assembly of sub‐nanoscale to protein sized molecules and even colloidal aggregates of clusters many hundreds of nm in size and have many interesting properties. Here we will explore the dynamic self assembly of polyoxometalate clusters from the nanometer to the micron scale. For instance at the nano‐scale we have recently developed a new approach to examine the dynamic assembly of clusters using a flow system, and using this we have also been able to ‘trap’ the big ‘Mo 154 ’ wheel cluster {[Mo VI 130 Mo V 20 O 442 (OH) 10 (H 2 O) 60 ] 14‐ complete with the templating ‘Mo 36 ’ [Mo VI 36 O 112 (H 2 O) 16] 8‐ cluster essential for the self assembly of the big wheel. Further, we will discuss non‐equilibrium structured assemblies using cation exchange, see Figure, reactions at interfaces, as well as the possibility of setting up complex interconnected reaction pathways in solution to form self‐organizing and emergent inorganic systems.

 

Title:Exciting World of Theoretical Studies of Chemical Reactions - From Gas Phase Reactions to Nano Structures, Catalysts, and Enzymatic Reactions
Speaker:Professor Keiji Morokuma
Date:26 March 2012
Time:2pm – 3.30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract: 

The chemical reaction which creates, destroys, reorganizes chemical bonds to produce new compounds is the most important subject of chemistry. I have been absorbed by this exciting world of chemical reactions from the beginning of my career for more than fifty years, since a hand-powered calculator was used to solve Hückel secular equations for frontier electron densities of simple aromatic hydrocarbons. Theoretical/computational studies have come a long way and are now playing the central role in understanding the mechanism and dynamics of chemical reactions and in helping designing more useful chemical reactions and catalysts. The theory can study not only the reaction of the ground state of molecules in gas phase but also reactions of excited electronic states as well complicated reactions of complex molecular systems. The information theoretical/computational studies can provide is often complementary to the information experimental studies provide, and research on chemical reactions is becoming impossible without strong collaboration between theorists and experimentalists.

I will discuss a few recent examples of our recent theoretical/computational studies on A. efficient determination of reaction pathways; B. the first excited-state “roaming” pathway for photodissociation of NO3 ; C. self-assembly reactions of small carbon clusters to form fullerenes and carbon nanotubes; D. homogeneous catalysis, E. reactions of metalloenzymes in protein environment, and F. chemical processes involving excited electronic states of biomolecules.

 

Title:Electrochemical Synthesis of Organofluorine Compounds Toward Green Sustainable Chemistry
Speaker:Professor Toshio Fuchigami
Date:29 February 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract: 

Organofluorine compounds have distinctive chemical, physical, and biological properties. Recently, there has been increasing interest in the chemistry of organofluorine compounds, which have applications in a wide variety of fields such as material science and medicinal chemistry. However, their preparation is not so easy. Therefore, we have developed selective molecular conversion of organoflurine compounds and selective fluorination of organic heteroatom compounds including heterocycles by using electrochemical methods. We have also developed VOC-free selective electrochemical fluorination of organic molecules and conducting polymers in ionic liquid HF salts.1) 1) Anodic a-Methoxylation and a-Acetoxylation of Trifluoroethyl Sulfide Using Recyclable Solid-Supported Bases: Selective anodic amethoxylation and a-acetoxylation of trifluoroethyl sulfide was achieved using recyclable solid-supported bases.2,3) 2) Mediatory Use of Task-Specific Ionic Liquid for Selective Anodic Fluorination: A task-specific ionic liquid having iodoarene was prepared and it was successfully used as a mediator for anodic fluorination and fluorodesulfurization ion ionic liquid fluoride salts (Scheme 1).4,5) Both the mediator and ionic liquid fluoride salt were repeatedly used for the fluorination. 3) Selective Anodic Fluorination of Polymer in Ionic Liquid: Although it is quite difficult to carry out "Polymer Electrochemical Reaction", we have achieved selective anodic fluorodesulfurization of poly(fluorene) derivatives in ionic HF salt as shown in Scheme 2. 6) 4) Selective Anodic Fluorination Under Ultrasonication: High viscosity of ionic liquids causes extremely slow mass transport of substrates to the surface of electrode, which results in low fluorination efficiency. However, we found that ultrasonication markedly increased the yield and changed product- and stereoselectivity (Scheme 3).7) 5) Anodic Fluorination Using Metal Fluoride Salts: Anodic fluorination of heteroatom compounds was successfully carried out for the first time using metal fluoride salts like KF in tetraethylene glycol/MeCN.8) In addition, “Prins Cyclization in Ionic Liquids” will be mentioned (Scheme 4).9)

 

Title:“Hx-amides,” A New DNA Sequence Recognition Element for Targeting and Controlling Gene Expression in Cancer Cells
Speaker:Professor Moses Lee
Date:28 February 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract: 

Polyamides are non-fluorescent imidazole (I) and pyrrole (P)-containing analogs of distamycin. They bind to specific sequences of DNA via the minor groove and have the capacity to regulate gene expression. Polyamides are potential useful for the treatment of genetic or gene derived diseases, including cancer. Continuing efforts in the polyamide field are aimed at the design and development of novel DNA binding structures that have greater sequence specificity, higher binding affinity, improved cellular uptake, and enhanced localization in the nucleus. To address these challenges, our work has focused on the design of novel DNA binding molecules that are inherently fluorescent. Thus, the fluorescent moiety must be an integral component of the molecule, and it must exhibit DNA sequence recognition properties. Accordingly, we are pleased to report the design of such a sequence recognizing, fluorogenic benzimidazole moiety, which we have coined “Hx.” And combining Hx with polyamides creates a new family of DNA binders, called “Hx-amides.” To demonstrate the novelty and usefulness of Hxamides, a representative molecule Hx-IP was designed and synthesized to target the inverted CCAAT box-2 (ICB2) site found within the promoter of the topoisomerase IIa gene in mammalian cells. In this presentation, the design, synthesis, plus the DNA binding and biological properties of Hx-IP will be presented. Hx-IP exhibits excellent binding affinity and specificity for the ICB2 site, brightly fluoresces when bound to its target sequence, enters cells, and effectively concentrates in the nucleus as monitored by fluorescence microscopy.

 

Title:From Simple Small Ring Building Blocks to Potent Biologically Active Compounds
Speaker:Professor Armin de Meijere
Date:27 February 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Koichi Narasaka
Abstract: 

Advanced syntheses of a group of versatile and highly reactive building blocks, including the 2-substituted cyclopropylideneacetates 1a–d, [1] will be presented. Some synthetic applications towards various cyclopropyl-group containing amino acids and more complex structures including biologically active compounds like the analogues of TAN 1057 2, [2] and Demethoxy-fumitremorgine C 3, will be presented. In addition, versatile new accesses to variously substituted cyclopropylamines as well as the first enantioselective syntheses of the cyclopropylgroup containing natural products Belactosine A 4 [3] and Hormaomycin 5 [4] will be discussed.

[1] M. Limbach, S. Dalai, A. de Meijere, Adv. Synth. Catal. 2004, 346, 760–766. [2] M. Kordes, M. Brands, M. Es-Sayed, A. de Meijere, Eur. J. Org. Chem. 2005, 3008–3016. [3] O. V. Larionov, A. de Meijere, Org. Lett. 2004, 6, 2153–2156.

 

Title:Neutral bases and anionic organometallic complexes in ionic solvents: from discovery science to applications
Speaker:Professor Jason Clyburne
Date:22 February 2012
Time:2pm – 3.30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Dragoslav Vidovic
Abstract: 

Ionic liquids (ILs) have attracted attention because of their potential applications in various industrial settings, as well as for their “green properties”, namely negligent vapour pressure and high thermal stability. ILs offer unique opportunities to affect significant changes to the way chemists and industries perform their chemistry, but it is important to recognize that the properties of ILs are variable. Broad generalizations concerning important aspects such as reactivity, stability, and decomposition are tempting, but these features are widely variable. Here we report our studies examining the behaviour of ILs in various industrially relevant conditions. I will examine the volatility and thermal stability of a series of ionic liquids and compare the results to that obtained for polymeric solvents and a deep eutectic. Possible implications will be discussed. Finally, if time permits I will describe the use of strong C-centered bases in ILs including Grignard reagents, (RMgX), organozinc reagents (R2 Zn), and N-heterocyclic carbene (NHC) complexes of metals. Grignard and organozinc reagents are important sources of the formal carbanion [R]- and find extensive use in organic synthesis. NHCs, both as free carbenes, where they can behave as organocatalysts, and also as essential components of transition metal complexes, have a wide range of reactivity in either stoichiometric or catalytic reactions. I

 

Title:Neutral bases and anionic organometallic complexes in ionic solvents: from discovery science to applications
Speaker:Professor Jason Clyburne
Date:22 February 2012
Time:2pm – 3.30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Dragoslav Vidovic
Abstract: 

Ionic liquids (ILs) have attracted attention because of their potential applications in various industrial settings, as well as for their “green properties”, namely negligent vapour pressure and high thermal stability. ILs offer unique opportunities to affect significant changes to the way chemists and industries perform their chemistry, but it is important to recognize that the properties of ILs are variable. Broad generalizations concerning important aspects such as reactivity, stability, and decomposition are tempting, but these features are widely variable. Here we report our studies examining the behaviour of ILs in various industrially relevant conditions. I will examine the volatility and thermal stability of a series of ionic liquids and compare the results to that obtained for polymeric solvents and a deep eutectic. Possible implications will be discussed. Finally, if time permits I will describe the use of strong C-centered bases in ILs including Grignard reagents, (RMgX), organozinc reagents (R2 Zn), and N-heterocyclic carbene (NHC) complexes of metals. Grignard and organozinc reagents are important sources of the formal carbanion [R]- and find extensive use in organic synthesis. NHCs, both as free carbenes, where they can behave as organocatalysts, and also as essential components of transition metal complexes, have a wide range of reactivity in either stoichiometric or catalytic reactions. I

 

Title:Assembly of Organic Molecules in the Solid State: From New Structural Patterns to Potential Applications
Speaker:Professor Xu Zhengtao
Date:20 February 2012
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Philip Chan
Abstract: 

This talk strives to highlight the conceptual and practical implications of an interdisciplinary study across molecular syntheses and crystalline networks. Our synthetic endeavor is illustrated by a class of unconventional, backfolded dendrimers (e.g., L), which, as building blocks, lead to some of the most complex crystalline networks to date. Solid state network structures based on L and other tailor-made molecules will be presented, with emphasis on the correlation with the associated optical properties, including: white light emission, second harmonic generation, and luminescent sensing of heavy metals and small molecules (e.g., NH3 , H2S). The second part marries the two distinct fields of metal chalcogenides and coordination polymers, in order to achieve advanced composite electronic materials. Here we use a bifunctional molecule that binds its hard carboxylate groups to Eu(III) and form a robust, porous network, while enclosing AgCl via its soft sulfur side arms. The AgCl is then treated with H2S to form the dark-colored Ag2S species, while leaving the enclosing host net intact and upstanding. The resultant composite combines the rich electronic property of metal chalcogenides and the functional diversity of coordination solids, and provides a well-defined medium for exploring novel catalytic and electronic processes in the solid state.

 

Title:Toward “Turn-On” Fluorescence Sensing through the Reaction-based Approach
Speaker:Professor Kyo Han Ahn
Date:15 February 2012
Time:2:15pm – 3:45pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Cheol-Min Park
Abstract: 

Molecular sensing of analytes of biochemical, clinical and environmental significance with high selectivity and sensitivity has attracted contin uing research interest, for their potential applications to biochemical studies, disease diagnosis, and monitoring of hazardous substances. For these purposes, fluorescent probes have attracted great attention for their high sensitivity and operational simplicity. Many fluorescent prob es have been developed by combining a fluorescent dye with a recognition unit that interacts with a target analyte by weak molecular intera ctions such as H-bonding, cation-p, and electrostatic interactions. Such a supramolecular approach is valuable and essential; however, someti mes it is challenging to achieve a high level of selectivity toward certain target species and also to realize turn-on type fluorescent response f or the analytes that act as quenchers. To address these issues, we have explored turn-on fluorescent probes based on organic reactions. Alth ough the reaction-based approach was introduced a decade ago,1 its full potential remained unexplored until a recent resurgence in the dev elopment of fluorescent probes for heavy metal species. To realize analyte specificity as well as turn-on type fluorescence sensing for anion s pecies, we initiated the reaction based approach to sense anions such as cyanide and carboxylates. As a result, we have developed the first t urn-on sensing system for the anions based on the reaction based approach.2,3 In our continuous efforts in the development of turn-on fluor escence sensing systems based on chemical conversions, we also embarked on the fluorescent sensing of cations through the reaction based approach. In this seminar, I will present our efforts in the rational design of turn-on fluorescent probes by the reaction based approach.4–9

References Dujols, V.; Ford, F.; Czarnik, A. W. J. Am. Chem. Soc. 1997, 119, 7386 Chung, Y. M.; Raman, B.; Kim, D.-S.; Ahn, K. H. Chem. Commun. 2006, 186. Ryu, D.; Park, E.; Kim, D.-S.; Yan, S.; Lee, J. Y.; Chang, B.-Y.; Ahn, K. H. J. Am. Chem. Soc. 2008, 130, 2394. Chatterjee, A.; Santra, M.; Won, N.; Kim, S.; Kim, J. K.; Kim, S. B.; Ahn, K. H. J. Am. Chem. Soc. 2009, 131, 20 40. Santra, M.; Ryu, D.; Chatterjee, A.; Ko, S.-K.; Shin, I.; Ahn, K. H. Chem. Commun. 2009, 2115. Egorova, O. A.; Seo, H.; Chatterjee, A.; Ahn, K. H. Org. Lett. 2010, 12, 401. Santra, M.; Ko, S.-K.; Shin, I.; Ahn, K. H. Chem. Commun. 2010, 46, 3964. Jun, M. E.; Ahn, K. H. Org. Lett. 2010, 12, 2 790-2793. For a Feature Article, see: Jun, M. E.; Roy, B.; Ahn, K. H. Chem. Commun. 2011, 47, 7583-7601.

 

Title:Size Matters: [2]Rotaxanes, [3]Rotaxanes and “Small” Functionalised Rotaxanes Using the CuAAC Active Template Reaction
Speaker:Dr Stephen Goldup
Date:10 February 2012
Time:11.00am to 12.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract: 

The synthesis of mechanically interlocked molecules such as rotaxanes has fascinated chemists for over a century but it is only in the last three decades that methods for their synthesis in high yield have been established through the use of “passive” templates based on supramolecular interactions.[1] The active template approach, where a metal ion serves to both gather the covalent components and catalyse the formation the new mechanical bond is an even more recent development with huge synthetic potential.[2] We have recently extended this novel active template methodology to the synthesis of rotaxanes with “small” macrocycles and demonstrated the power of this approach through the realisation of rotaxanes with fully conjugated insulated threads , reactive functional groups for post-synthetic functionalization, molecules based on chiral-pool derived stoppers and systems with multiple mechanical bonds (shown).[3]

[1] J. F. Stoddart, Chem. Soc. Rev. 2009, 38, 1802-1820. [2] J. D. Crowley, S. M. Goldup, A.-L. Lee, D. A. Leigh, R. T. McBurney, Chem. Soc. Rev. 2009, 1530-1541. [3] H. Lahlali, K. Jobe, M. Watkinson, S. M. Goldup, Angew. Chem. Int. Ed. 2011, 50, 4151-4155.

 

Title:Interfacial Self-Assembly and Theranostic Applications of Inorganic-Organic Hybrid Nanomaterials
Speaker:Professor Ken Cham-Fai Leung
Date:9 February 2012 
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract:

Nanotheranostic materials have been recently involved in the use of nanoparticles for simultaneous diagnostic and therapeutic purposes. New materials have been extensively developed towards drug delivery and tumor imaging. In the first part of the presentation, the synthesis, characterization, and properties of theranostics nanoparticles based on organic-inorganic hybrid nanoparticles will be described. The hybrid nanoparticle consists of a superparamagnetic iron oxide core and a series of coatings which are stimuli-responsive supramolecules or polymers. By the concept of nanovalve based on supramolecular gate-keepers, stimuli-responsive drug delivery nanosystem was synthesized by (i)modified solvothermal reaction; (ii)sol-gel reaction; and (iii)coupling reaction of supramolecules. In these systems, the “ON/OFF” switching of the gatekeeper supramolecules can be controlled by pH-sensitive intramolecular hydrogen bonding or electrostatic interaction (such as metal chelating). Biological evaluation of the nanoparticles renders them non-cytotoxic and can be uptaken by several cell types. The anti-tumor drug (doxorubicin) loading and release profiles which were studied by the UV/visible absorption spectroscopy, were demonstrated by using ultrasonic wave. Magnetic resonance imaging analysis of the particles reveals a high relaxivity, rendering them useful nanotheranostic agents. The second part of the talk will focus on the synthesis, purification, characterization and sensing application of mono-amine functionalized gold nanoparticles (AuNPs). The crude mono-amine functionalized AuNPs were purified by magnetic separation via pHswitchable pseudorotaxane formation. Then, discretely mono-amine functionalized AuNPs could be simultaneously purified and detected by a real-time surface plasmon resonance(SPR) with organic solvent-compatible microfluidic device/instrumentation. The discretely functionalized AuNPs were further explored as a probe for DNA sensing which is complementarily with the sequence of the pathogenicity island of vancomycin-resistant Enterococcus faecalis.

Reference: 1. K. C.-F. Leung, S. H. Xuan, X. M. Zhu, D. W. Wang, C.-P. Chak, S.-F. Lee, W. K.-W. Ho, B. C.-T. Chung Chem. Soc. Rev., 2012, in press. 2. S. Xuan, F. Wang, J. M. Y. Lai, K. W.-Y. Sham, Y.-X. J. Wang, S.-F. Lee, J. C. Yu, C. H. K. Cheng, K. C.-F. Leung ACS Appl. Mater. Interfaces 2011, 3, 237. 3. C.-P. Chak, L.-H. Chau, S.-Y. Wu, H.-P. Ho, W. J. Li, P. M. Mendes, K. C.-F. Leung J. Mater. Chem. 2011, 21, 8317. 4. S. H. Xuan, F. Wang, X. L. Gong, S. K. Kong, J. C. Yu, K. C.-F. Leung Chem.Commun. 2011, 47, 2514. 5. C.-P. Chak, S. Xuan, P. M. Mendes, J. C. Yu, C. H. K. Cheng, K. C.-F. Leung ACS Nano 2009, 3, 2129.

 

Title:The Beauty and Promise of Molecular Nanotechnology
Speaker:Professor Sir Fraser Stoddart
Date:7 February 2012 
Time:11:30am – 1:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract:This lecture will highlight the contribution that the introduction of a brand new chemical bond, often called the mechanical bond, into molecules that constitute chemical compounds is making to the construction of nanoscale entities, many of which turn out to be works of art with intellectually stimulating and visually captivating topological forms in their own right. Yet other nanoscale entities, where function has been incorporated along with structural form, are finding their way, through the fabrication of integrated systems, into molecular electronic devices and drug delivery systems. Nanoelectromechanical systems in the shape of artificial molecular switches, however, are now a dime a dozen. The grand challenge — similar in many ways to that faced by the early aviators of just over a century ago — which confronts molecular nanotechnologists today is to make that daring leap forward from switches to the machines of tomorrow, egged on by the fact that we ourselves operate in large measure under the exquisite control of sophisticated molecular machinery.

 

Title:Zinc Cluster Catalyzed Transesterification and Oxazoline Synthesis
Speaker:Professor Kazushi Mashima
Date:3 February 2012 
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Shunsuke Chiba

 

Title:Zinc Cluster Catalyzed Transesterification and Oxazoline Synthesis
Speaker:Professor Kazushi Mashima
Date:3 February 2012 
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Shunsuke Chiba

 

Title:Transition-Metal-Catalyzed Borylation and Silylation: New Functionalization Methods of Organic Molecules
Speaker:Dr Toshimichi Ohmura
Date:2 February 2012 
Time:10:45am – 12:15pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract: 

Organoboron and organosilicon compounds have played important roles in organic synthesis, medicinal chemistry, and materials sciences. In this presentation, I am going to describe some new regio- and stereoselective synthetic routes to these compounds utilizing transitionmetal-catalyzed C-B and C-Si bond formations. Synthetic applications of these compounds to catalytic C-C bond formations will also be demonstrated.

 

Title:Bioactive Natural Products and Chirality
Speaker:Professor Kenji Mori
Date:1 February 2012 
Time:10:30am – 12:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Koichi Narasaka
Abstract: 

Mori’s synthetic works on bioactive natural products in general and pheromones in particular started about forty years ago to establish their absolute configurations and also to clarify their stereochemistry-bioactivity relationships. Results indicate that bioactive natural products are not always enantiomerically pure, and the stereochemistry-bioactivity relationships are not simple but complicated. For example, neither (R)- nor (S)-sulcatol, the aggregation pheromone of an ambrosia beetle, is behaviorally bioactive, while their mixture is active. In the case of olean, the sex pheromone of the olive fruit fly, its (R)-isomer is active against the males, and the (S)-isomer activates the females. Recent synthesis of new insect pheromones will be discussed to illustrate the modern methods in enantioselective synthesis..

 

Title:Direct Amination of Allylic Alcohols and Benzyl Alcohols by Pt and Au
Speaker:Professor Kazushi Mashima
Date:30 January 2012
Time:11.00am – 12.30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Leung Pak Hing
Abstract: 

Transition metal-catalyzed amination of allylic compounds via π-allylmetal intermediate is one of the most powerful and useful methods for the synthesis of allylamines. From an environmental and economical point of view, a direct catalytic substitution of allylic alcohols, which forms water as the sole coproduct, has recently caught much attention. In this lecture, our recent results on the development of a versatile direct catalytic amination of allylic alcohols and benzylic alcohols with various amines using Pt and Au catalyst systems.

(1) Platinum-Catalyzed Direct Amination of Allylic Alcohols with Aqueous Ammonia for Selective Synthesis of Primary Allylamines. K. Das, Y. Nakahara, R. Shibuya, N. Germain, T. Ohshima, and K. Mashima, Angew. Chem. Int. Ed., 51, 150-154 (2012).

(2) Direct substitution of the hydroxy group with highly functionalized nitrogen nucleophiles catalyzed by Au(III). T. Ohshima, Y. Nakahara, J. Ipposhi, Y. Miyamoto, and K. Mashima, Chem. Commun., 47, 8322-8324 (2011).

(3) Platinum-Catalyzed Direct Amination of Allylic Alcohols under Mild Conditions: Ligand and Microwave Effects, Substrate Scope, and Mechanistic Study T. Ohshima, Y. Miyamoto, J. Ipposhi, Y. Nakahara, M. Utsunomiya, and K. Mashima, J. Am. Chem. Soc., 131, 14317-14328 (2009).

 

Title:Controlled Synthesis and Assembly of Carbon based Materials for New Applications
Speaker:Dr Yu Zhu
Date:20 January 2012
Time:11.00am – 12.30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Li Tianhu
Abstract: 

As low dimensional materials, graphene and carbon nanotubes (CNT) exhibit exceptional properties such as high carrier mobility, high electrical and thermal conductivity and large specific surface area, which render them promising materials in many applications. By controlling synthesis and assembly, the exotic properties of graphene and CNT were able to be extended to macro-scale. These materials have been successfully applied in transparent electrode, thin film transistor, energy storage devices and various other applications. Conjugated polymers are another type of semi-conductive materials which are suitable for flexible electronics. Starting from a commercial dye molecule (diketopyrrolopyrrole), we demonstrated that stable conjugated polymers can be achieved and applied in many organic electronics applications.

 

Title:Chemical design of multi-component nanocrystal assemblies and nanocrystal based devices
Speaker:Professor Christopher B. Murray
Date:13  January 2012
Time:11.00am – 12.30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Ling Xing Yi
Abstract: 

 

The synthesis of colloidal nanocrystals (NCs) with controlled crystal shape, structure and surface passivation provides ideal building blocks for the assembly of new thin films and devices. The NCs are "artificial atoms" with tunable electronic, magnetic, and optical properties. This talk will briefly outline some of the current "best practices" in assembly and integration of NC superlattices. I will focus on the properties that emerge in single component superlattices that retain and enhance many of the desirable mesoscopic properties of individual NCs and explore how these novel building blocks are integrated into a range of electronic, magnetic and optical devices. Multi-component assembly at the nanoscale is accelerating the design new materials and devices with the creation binary and ternary NC superlattices (BNSLs & TNSLs). I will show how we organize differently sized CdSe, CdTe, PbS, PbSe, PbTe, CuInS2, FePt, CoPt3 , Fe3O4 , CoFe2O4 , Au, Ag, Pd, Pt, Pt, Ni,and NaYF4:Re (Re=rare earths) nanocrystals among other systems into a rich array of multi-functional superlattices or metamaterials (in which the coupling and spatial relation of components dictate the system’s response). I will share methods we have recently established to direct superlattice formation by interfacial assembly and transfer and demonstrate how pushing to assembly conditions far from equilibrium can drive the process into oscillatory deposition producing films with controlled periodicity on both the nano and micro scales. I will describe strategies for the fabrication of devices based on these new multi-component nanoscale assemblies share our Penn team’s recent observations of emergent physical phenomena in these assemblies including “band like” transport in the NC assemblies.

 

 

Title:Shape-Controlled Synthesis of Nanocrystals and Their Facet-Dependent Properties
Speaker:Professor Michael Huang
Date:11 January 2012
Time:11.00am – 12.30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Ling Xing Yi
Abstract: 

Our group has developed facile methods for the syntheses of Au, Cu2O, and Ag2O nanocrystals with systematic shape evolution from cubic to octahedral, rhombic dodecahedral, and hexapod structures. The methods are water-based, easy to follow, relatively fast, low in cost, conducted at room temperature (or slightly warmed), and highly effective in shape control. Thus, the synthetic approaches are energyefficient and environmentally friendly. New insights regarding the nanocrystal growth mechanism has been obtained from these studies. Using Au nanocubes as cores, we have synthesized Au–Pd core–shell nanocrystals with a tetrahexahedral structure exposing high-index {730} facets. We have also used Au nanocrystal cores for the fabrication of Au–Cu2O core–shell heterostructures with well-defined shapes and specific exposed facets. They can transform into cubic and octahedral Cu2 S nanocages by forming thin Cu2 S shells first and then removing the Cu2O cores. The nanocrystals with well-defined shapes allow for their facet-dependent property investigations. Photocatalytic activity and electrical conductivity of Cu2O crystals were found to be highly facet-dependent and Au nanocrystal-enhanced. SERS sensitivity of gold nanocubes, octahedra, and rhombic dodecahedra has been compared. These morphology–property studies should represent a new and exciting direction for nanomaterials research.

References [1] C.-H. Kuo, Y.-C. Yang, S.Gwo, M. H. Huang, J. Am. Chem. Soc. 2011, 133, 1052–1057. [2] L.-M. Lyu, W.-C. Wang,M. H. Huang, Chem.–Eur. J. 2010, 16, 14167–14174. [3] W.-C. Wang, L.-M. Lyu,M. H. Huang, Chem. Mater. 2011, 23, 2677–2684. [4] C.-H. Kuo, T.-E. Hua, M. H. Huang, J. Am. Chem. Soc. 2009, 131, 17871–17878. [5] H.-L. Wu, C.-H. Kuo, M. H. Huang, Langmuir 2010, 26, 12307–12313. [6] C.-L. Lu, K. S. Prasad, H.- L. Wu, J.-a. A. Ho, M. H. Huang, J. Am. Chem. Soc. 2010, 132, 14546–14553. [7] J.-Y. Ho, M. H. Huang, J. Phys. Chem. C 2009, 113, 14159– 14164. [8] C.-H. Kuo, M. H. Huang, J. Phys. Chem. C 2008, 112, 18355–18360. [9] C.-H. Kuo, Y.-T. Chu, Y.-F. Song, M. H. Huang, Adv. Funct. Mater. 2011, 21, 792–797. [10] P.-J. Chung, L.-M. Lyu, M. H. Huang, Chem.–Eur. J. 2011, 17, 9746–9752.

 

 

Title:Transition-Metal Catalyzed Cyclization and C-H Functionalization Reactions
Speaker:Professor Wu Ming-Jung
Date:10 January 2012
Time:10:45am – 12:15pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract: 

 

Treatment of N,N-dimethyl 2-[(2-(2-alkynylphenyl)ethynyl)anilines with ten mol% of PdCl2 and two equivalents of CuCl2 at refluxing THF for one hour gave the chlorinated benzo[a]carbazolesin excellent yields. A chloroindoles was proposed as the key Intermediate and prepared separately by reaction of N,N-dimethyl 2-[(2-(2-alkynylphenyl)-ethynyl) anilines with two equivalents of CuCl2 at refluxing THF. Treatment of this chloroindole with various electrophilic transition metals, such as PdCl2 , Pd(OAc)2 , PtCl2 and Ph3AuCl, gave benzo[a]carbazoles in good yields. This synthetic method has been extended to the synthesis of dibenzo[b,d]pyran-6-ones and dibenzothiophenes.

In the development of new synthetic method through C-H activation, potassium aryltrifluoroborates are superior to aryl boronic acids in the ortho-arylation of 2-phenylpyridines, 2-phenoxypyridines and N-phenylpyridin-2-amines. p-Benzoquinone is found to play as an important ligand for transmetallation reductive elimination step in the catalytic process.