Seminars 2015

Title:Synthesis, Optics and Biomedical Applications of Plasmonic Nanostructures with Ultrasmall Nanogap
Speaker:Professor Jwa-Min Nam
Date: 6th August 2015
Time: 3.30pm to 5.00pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Chen Hongyu
Abstract: 

Designing, synthesizing and controlling plasmonic nanostructures such as Au and Ag nanoparticles with high precision and high yield are of paramount importance in optics, nanoscience, nanobiotechnology and materials science. It is particularly important and challenging to generate and control ~1-nm plasmonic gap between and inside particles or targeted nanostructures with strong plasmonic field because of their potentials as the optical platforms with larger signal amplification and more quantitative signal output. Here, I will describe various functional molecule(e.g., DNA, protein, polymer, etc)-based synthetic strategies to build up new types of plasmonic nanostructures with high structural controllability and the optical properties of these nanostructures. Further, the use of these plasmonic nanostructures as excellent optical signal enhancement, biosensing and therapeutic platforms will be also shown and discussed.

References 1. Oxidative Nanopeeling Chemistry-Based Synthesis and Photodynamic and Photothermal Therapeutic Applications of Plasmonic CorePetal Nanostructures, J. Am. Chem. Soc., 136, 16317 (2014). 2. Plasmonic Nanosnowmen with a Conductive Junction as Highly Tunable Nanoantenna Structures and Sensitive, Quantitative and Multiplexable Surface-Enhanced Raman Scattering Probes, Nano Letters, 14, 6217 (2014). 3. Thiolated DNA-Based Chemistry and Control in the Structure and Optical Properties of Plasmonic Nanoparticles with Ultrasmall Interior Nanogap, J. Am. Chem. Soc., 136, 14052 (2014). 4. Massively Parallel and Quantitative Single-Particle Analysis on Interactions between Plasmonic Nanoparticles on Supported Lipid Bilayer, J. Am. Chem. Soc., 136, 4081 (2014). 5. Single-Molecule and Single-Structure-Based Correlation Studies between Localized Surface Plasmons of Dimeric Nanostructures with ~1-nm Gap and Surface-Enhanced Raman Scattering, Nano Letters, 13, 6113 (2013). 6. Directional Synthesis and Assembly of Bimetallic Nanosnowmen with DNA, J. Am. Chem. Soc. 134, 5456 (2012). 7. Highly Uniform and Reproducible Surface-Enhanced Raman Scattering from DNA-Tailorable Nanoparticles with 1-nm Interior Gap, Nature Nanotechnology, 6, 452 (2011). 8. Nanogap-Engineerable, Raman-Active Nanodumbbells for Single-Molecule Detection, Nature Materials, 9, 50 (2010).

 

Title:The Science and Technology of Quantum Dots
Speaker:Professor Moungi Bawendi
Date: 6th August 2015
Time: 11.00am to 12.30pm 
Venue:NTU SPMS LT 4
Host: Assistant Professor Loh Zhi Heng 
Abstract: Semiconductor nanocrystals, aka quantum dots, are the prototypical material for the emergence of new properties when dimensions are reduced to the nanometer range. The size dependent properties of excitons and multiexcitons in quantum dots, coupled with a material that can be processed from solution, has led to applications in displays, solar energy conversion, and biological and biomedical fluorescence imaging, with commercial products containing quantum dots in the market. A fundamental understanding of excitonic processes is essential in any of these applications. Synthesis of well-characterized materials is also crucial, not only of the functional inorganic particle itself, but also the ligand shell that protects it and couples it chemically to molecules and matrices of interest. This talk will explore the chemistry, photophysics, and applications of quantum dots, ranging from fundamental excitonic properties, to applications in displays and photovoltaic devices and to biological applications of quantum dots for in vivo imaging in animal models. We will focus on (a) aspects of spectroscopy that inform on the excitonic properties, especially at the single quantum dot level, (b) device physics and applications in PV, and (c) in vivo biological imaging with quantum dot probes in the short wave infrared (1-2 micron).

 

Title:Supramolecular Systems at Work
Speaker:Professor Stefan Matile
Date: 5th August 2015
Time: 4.30pm to 6.00pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Tan Choon Hong
Abstract: 

This lecture will focus on synthetic supramolecular systems with interesting functions. Particular emphasis is on lessons from nature and the integration of unusual interactions such as anion-π interactions,[1] halogen bonds,[1] orthogonal dynamic covalent bonds[2] and mechanosensitive bonds. [3] Focus will be on topics of current interest. This includes catalysis with anion-π interactions, from Kemp elimination to enolate and asymmetric enamine chemistry. [4] Existence and relevance of ionpair-π interactions on push-pull chromophores will be discussed. [5] Up to three orthogonal dynamic covalent bonds are used in concert to construct functional surface architectures of highest possible sophistication with highest possible precision. [2] Functions of interest include double-channel photosystems with antiparallel threecomponent redox gradients,[6] or ion-gated photosystems. [7] Substrate-initiated ring-opening disulfide-exchange polymerization and ring tension are applied to dynamic covalent chemistry to find new ways to enter into cells. [8] Mechanosensitive bonds, finally are decisive for the development of new fluorescent probes that change color like lobsters during cooking and feel central characteristics of lipid bilayer membranes such as tension, potential and disorder. [3]

References: 1. Vargas Jentzsch, A.; Hennig, A.; Mareda, J.; Matile, S. “Synthetic Ion Transporters that Work with Anion-π Interactions, Halogen Bonds and Anion-Macrodipole Interactions,” Acc. Chem. Res. 2013, 46, 2791-2800. 2. Wilson, A.; Gasparini, G.; Matile, S. “Functional Systems with Orthogonal Dynamic Covalent Bonds,” Chem. Soc. Rev. 2014, 43, 1948-1962. 3. Dal Molin, M.; Verolet, Q.; Soleimanpour, S.; Matile, S. “Mechanosensitive Membrane Probes,” Chem. Eur. J. 2015, 21, 6012-6021. 4. Zhao, Y.; Beuchat, C.; Mareda, J.; Domoto, Y.; Gajewy, J.; Wilson, A.; Sakai, N.; Matile, S. “Anion-π Catalysis,” J. Am. Chem. Soc. 2014, 136, 2101-2111. 5. Fujisawa, K.; Beuchat, C.; Humbert-Droz, M.; Wilson, A.; Wesolowski, T. A.; Mareda, J.; Sakai, N.; Matile, S. “Anion-π and Cation-π Interactions on the Same Surface,” Angew. Chem. Int. Ed. 2014, 53, 11266-11269. 6. Hayashi, H.; Sobczuk, A.; Bolag, A.; Sakai, N.; Matile, S. “Antiparallel Three-Component Gradients in Double-Channel Surface Architectures,” Chem. Sci. 2014, 5, 4610-4614. 7. Sakai, N.; Charbonnaz, P.; Ward, S.; Matile, S. “Ion-Gated Synthetic Photosystems,” J. Am. Chem. Soc. 2014, 136, 5575- 5578. 8. Gasparini, G.; Bang, E.-K.; Montenegro, J.; Matile, S. “Cellular Uptake: Lessons from Supramolecular Organic Chemistry,” Chem. Commun. 2015, 51, 10389-10402.

 

Title:Asymmetric Hydrogenation of N-Heteroaromatics by Iridium-Chiral Diphosphine Catalysts
Speaker:Professor Kazushi Mashima
Date: 5th August 2015
Time: 3.00pm to 4.00pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Shunsuke Chiba 
Abstract: 

Catalytic asymmetric hydrogenations of prochiral unsaturated compounds including C=C, C=O, and C=N bonds have been intensively investigated in terms of most versatile and environmentally benign processes for creating a chiral carbon center. Asymmetric hydrogenation of N-heteroaromatic compounds has been considered as difficult task because of the resonance stability of such the N-heteroaromatic compounds; recent developments on asymmetric hydrogenation of N-heteroaromatic compounds such as 2-substituted quinolines and quinoxalines, giving the corresponding 1,2,3,4-tetrahydroquinoline and 1,2,3,4-tetrahydroquinoxaline derivatives in high enantioselectivity, have been remarkable and outstanding. Herein, we report asymmetric hydrogenation of 2-substituted quinoxalines 3 using chiral cationic dinuclear triply chloride-bridged iridium complexes [{Ir(H)[diphosphine]}2(m-Cl)3 ]Cl [(S)-1a: diphosphine = (S)-BINAP; (S)-2a: diphosphine = (S)- SEGPHOS], and asymmetric hydrogenations and mechanisms of isoquinolinium salts, quinazolinium salts and pyridinium salts are discussed.

(1) Effect of Salt Formation on Asymmetric Hydrogenation of Isoquinolinium Salts Catalyzed by Ir Complex. Yusuke Kita, Kenta Yamaji, Kosuke Higashida, Kandula Sataiah, Atsuhiro Iimuro, Takuto Nagano, and Kazushi Mashima, Chem. Eur. J., 21, 1915–1927 (2015). Highlighted as front cover of journal. (2) Asymmetric Hydrogenation of Quinazolinium Salts Catalysed by Halide-bridged Dinuclear Iridium Complexes bearing Chiral Diphosphine Ligands. Yusuke Kita, Kosuke Higashida, Kenta Yamaji, Atsuhiro Iimuro, and Kazushi Mashima, Chem. Commun., in press (2015). (3) Iridium-catalyzed Asymmetric Hydrogenation of Pyridinium Salts for Constructing Multiple Stereogenic Centers on Piperidines. Yusuke Kita, Atsuhiro iimuro, Shoji Hida, Kazushi Mashima, Chem. Lett., 43, 384-386 (2014). (4) Asymmetric Hydrogenation of Isoquinolinium Salts Catalyzed by Chiral Iridium Complexes: Direct Synthetic Protocol for Optically Active 1,2,3,4-Tetrahydroisoquinolines. Atsuhiro Iimuro, Kenta Yamaji, Sathaiah Kandula, Takuto Nagano, Yusuke Kita, and Kazushi Mashima, Angew. Chem. Int. Ed., 52, 2046-2050 (2013). (5) Additive Effects of Amins on Asymmetric Hydrogenation of 2-Substituted Quinoxalines Catalyzed by Chiral Iridium Complexes. Takuto Nagano, Atsuhiro Iimuro, Rino Schwenk, Takashi Ohshima, Yusuke Kita, Antonio Togni, and Kazushi Mashima, Chem. Eur. J., 18, 11578-11592 (2012).

 

Title:Boron- or Aluminum Lewis Acids with Organic Cage-Shaped Framework as a Catalyst for Selective Recognition of Aromatic Compounds
Speaker:Professor Makoto Yasuda
Date: 5th August 2015
Time: 2.00pm to 3.00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Shunsuke Chiba 
Abstract: Group 13 metal compounds, ML3 , constitute one of the most important classes of Lewis acids. We recently studied cage-shaped boron complexes as a new type of Lewis acid. Boron complexes usually have a planar structure that is exemplified by triphenyl borate, which demonstrates weak Lewis acidity by conjugation between a lone oxygen pair and a vacant p-orbital on boron. When the boron complexes were surrounded by a cage-shaped organic framework, they showed a quite different character and acted as a catalyst with a Lewis acidity that was finely tunable. By introducing ortho-aryl groups to the complex, the p-pocket of the boron center contributed to the selectivity of aromatic compounds over aliphatic compounds during organic synthesis (Angew. Chem., Int. Ed. 2012, 51, 3867). The aluminum derivatives showed higher selectivity. The metal complexes were also applied to an asymmetric synthesis.

 

Title:Gold-catalysis: Diverse Transformations and Selectivity Control
Speaker:Professor Zhang Junliang
Date: 5th August 2015
Time: 11.15am to 12.45pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Steve Zhou
Abstract: Homogeneous Gold(I)-catalysis have emerged a powerful tool in organic sythesis. Cycloaddition reactions which provide efficient tools for the chemo-, regio-, and diastereoselective construction of highly substituted medium-sized ring systems from simple acyclic starting materials, have received much attention. This lecture will describe a rich variety of new synthetic methods that are based on gold- catalyzed cycloaddition and cyclization reactions developed in our group since 2009. These reactions amied at the efficient construction of carbo- and heterocycles, especially highly substituted furans and pyrroles, feature the following issues: 1) new understanding of the difference between the carbophilic gold catalysts and the oxophilic Lewis catalysts; 2) selective control of mutiple functional compounds; 3) synthesis of different products from the same starting material(s) by sutiable choice of different catalysts; and 4) in-depth investigations of reaction mechanisms and then design of novel cycloaddition or cyclization reactions. We also present a chemoselective C-H insertion reaction of phenol and diazo compounds.

 

Title:Morphology dependent device physics of organic solar cells
Speaker:Professor Girish Lakhwani
Date: 4th August 2015
Time: 2.00pm to 3.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Soo Han Sen
Abstract: 

Here I will discuss the influence of nanoscale morphology – bulk and interfacial - on the J-V characteristics and the efficiency of organic solar cells. In particular, I will discuss our past work on bulk-heterojunction PTB7/PCBM solar cells, where we observed increase in the short circuit current as a result of improved bulk morphology due to diiodooctance (DIO) treatment. We found that DIO treatment reduced trap-assisted recombination in these devices resulting in improved EQE. On the other hand, methanol treatment on similar devices resulted in an increase of the open circuit voltage (Voc). Part of this increase in Voc could be explained as a result of improved charge extraction and reduced charge recombination caused by changes in electronic properties at the interface between the photoactive layer and the PEDOT:PSS. Using both spatial and temporal resolution of charge dynamics, we also found evidence for hole accumulation at the electrode on the nanosecond timescale, and show that this can limit charge transport through space charge effects at solar illumination condition.

In the end, I will briefly discuss our efforts in understanding nanoscale evolution of morphology in conjugated polymer thin films from single molecule and local exciton- coupled systems to bulk long-range ordered systems, whereby the photophysical properties such as energy and charge transfer change significantly.

 

Title:Molecular imaging tools for the study of oxidative stress and metal ions in biology
Speaker:Professor Elizabeth New
Date: 4th August 2015
Time: 11.00am to 12.30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Soo Han Sen
Abstract: 

While there are now many sophisticated imaging techniques to study biological systems, chemical tools are needed to gain an understanding of what is happening in the cell, on a molecular level. We are interested in designing small molecule sensors to probe sub-cellular molecular species, especially those with a fluorescence or magnetic resonance output.

In particular, we are developing redox-responsive sensors that are able to report on reversible oxidative events in biological systems, and can distinguish transient oxidation events from oxidative stress. We also have an interest in imaging essential and therapeutic metals within cells using selective fluorescent sensors, and in measuring toxic metals in the environment using fluorescent arrays.

 

Title:Towards Control of Selectivities in Transition-Metal Catalysis
Speaker:Professor Hou Xue Long
Date: 3rd August 2015
Time: 3.00pm to 4.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Steve Zhou 
Abstract: Some strategies have been developed in our group, with which, the tuning of regio-, diastereo- and enantio-selectivities have been realized in some transition-metal catalyzed reactions. The factors influencing the selectivities of the reactions will be discussed and some qualitative models will be proposed to rationalize the observed stereoselectivity.

 

Title:Organic Electron Donors
Speaker:Professor John Murphy
Date: 14th July 2015
Time: 3.30pm to 4.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Shunsuke Chiba

 

Title:Photoredox catalysis - Enabling methodologies and complex molecule synthesis
Speaker:Professor Corey Stephenson
Date: 14th July 2015
Time: 2.30pm to 3.30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Shunsuke Chiba
Abstract: Single electron transfer (SET) processes – frequently utilized by Nature to activate its substrates – significantly enhance the reactivity of organic molecules. These SET reactions provide facile access to neutral radicals – reactive intermediates that are particularly attractive for use in complex settings as a consequence of their general lack of reactivity with polar functional groups. This lecture will describe the evolution of our general program focused on visible light mediated electron transfer catalysis, moving toward greater mechanistic understanding and utility in highly complex settings. Specifically, our approach toward the synthesis of alkaloid natural products and a strategy for room temperature degradation of lignin will be discussed.

 

Title:Proton-coupled electron transfer in organic synthesis and asymmetric catalysis
Speaker:Professor Robert Knowles
Date: 13th July 2015
Time: 3.00pm to 4.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Shunsuke Chiba

 

Title:Functional Materials for Energy Conversion
Speaker:Professor Ho Cheuk Lam
Date: 7th July 2015
Time: 2.30pm to 4.00pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Professor Loh Teck Peng
Abstract: Since the quality of our life depends to a large extent on the availability of energy, the energy crisis problem will pose a great threat to us for the foreseeable future and energy is and will certainly remain one of the great challenges for the world. It is critically essential to find alternative forms of renewable energy sources. Currently, people are talking about renewable energy in various scientific disciplines around the world and these terms are frequently brought to wide public attention. There is great interest in developing renewable resources and improving the technologies for energy interconversions. The transformations of light into electricity (electrical energy generation in photovoltaic cells) and electricity into light (light generation in light-emitting diodes) are two important interrelated areas that have attracted considerable research interest in recent years. Functional organometallic and organic molecules have become a field of intense activities in the optoelectronic research. They hold great promise for use in energy interconversions. The chemical and physical properties of such functional materials can be easily fine-tuned simply by varying its chemical structures to develop the best materials to fit a particular energy conversion application. This lecture presents a critical perspective of the field, with emphasis on fundamental concepts and current applications.

 

Title:Tracking Energy Flow from the Nano to Mesoscale with Ultrafast Nanoscopy
Speaker:Professor Huang Libai
Date: 3rd July 2015
Time: 4.30pm to 6.00pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Chen Gang 
Abstract: 

The frontier in solar energy conversion utilizing molecular and nanostructure components now lies in learning how to integrate functional entities across multiple length scales to create optimal devices. To address this new frontier, I will discuss our recent efforts on elucidating multi-scale energy transfer, migration, and dissipation processes with simultaneous femtosecond temporal resolution and nanometer spatial resolution. We have combined/correlated ultrafast spectroscopy with high spatial resolution techniques such as optical microscopy and scanning probe microscopy to achieve high-resolution spatial mapping of charge carrier dynamics in nanostructures and solar energy harvesting systems.

 

Title:Synthesis and applications of cyclic carbonates
Speaker:Professor Michael North
Date: 3rd July 2015
Time: 3.00pm to 4.30pm  
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Tan Choon Hong
Abstract: 

Carbon dioxide is a cheap, abundant and non-toxic sustainable carbon source for chemical industries. Therefore, the development of new catalytic processes that use carbon dioxide as feedstock has generated great attention in recent years. Among these processes, the reaction of epoxides 1 and carbon dioxide can afford either polycarbonates 2 or cyclic carbonates 3 and is a 100% atom-economic transformation (Scheme 1). Cyclic carbonates are the thermodynamic product of the reaction and have many applications including as electrolytes for lithium ion batteries, solvents and chemical intermediates. Scheme 1: Synthesis of poly¬¬– and cyclic carbonates.

In this lecture, the development of bimetallic aluminium(salen) complex 4 and Bu4NBr as a catalyst system for the synthesis of cyclic carbonates at room temperature and pressure will be described. Recent kinetic studies on the synthesis of glycerol carbonate 3g at temperatures of 25-100 oC, carbon dioxide pressures of 1-100 bar and catalyst loadings of 0.1-2.5 mol% have shown that there is an optimal carbon dioxide pressure (50 bar) for the reaction (Figure 1). Under these conditions, complex 4 is catalytically active in the absence of a cocatalyst. To demonstrate the utility of this process, eight cyclic carbonates 3a–h have been prepared from terminal epoxides 1a–h and carbon dioxide under solvent free conditions. The importance of these results is that they simplify the catalyst system and avoid the cost, corrosion and purification issues associated with the use of ammonium halide or basic cocatalysts.

The direct synthesis of cyclic carbonates from diols using zinc catalysts will also be reported, as use of cyclic carbonates as green polar aprotic solvents for organocatalysed reactions.

 

Title:Bioinspired Synthesis and Characterization of Organic Nanowires
Speaker:Professor Alon Gorodetsky
Date: 3rd July 2015
Time: 11.00am to 12.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Liu Xuewei
Abstract: 

One-dimensional organic nanowires and nanoribbons represent idealized model systems for investigating charge transport mechanisms at molecular length scales. However, there are significant difficulties associated with the synthesis of organic nanowires and nanoribbons with precisely defined sequences, lengths, geometries, and terminal functionalities. By drawing inspiration from the structure of DNA and from automated oligonucleotide synthesis techniques, we have developed facile strategies for the covalent assembly of organic semiconductor building blocks into precisely defined one-dimensional ensembles. We have investigated the properties of these nanowires with a combination of spectroscopic, x-ray diffraction, and electrochemical techniques. Our findings hold significance both for fundamentally understanding nanoscale charge transport phenomena and for the development of new types of biological and molecular electronic devices.

 

Title:Designer synthetic polypeptides for structural hydrogels and responsive nano-delivery
Speaker:Professor Paula Hammond
Date: 2nd July 2015
Time: 2.00pm to 3.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Liu Xuewei
Abstract: 

Synthetic polypeptides provide the basis for new biomacromolecules that can be modified to achieve a broad range of biologically relevant function. We have designed poly(propargyl-L-glutamate) (PPLG) synthetic polypeptides to which different molecules can be “clicked” to achieve dense brush polypeptide backbone structures, helical rod/coil polymers that form the basis of unique hydrogels, and temperature and pH responsive polymers. Crosslinking of dense PEG grafted PPLG molecules with an alpha-helical backbone can lead to gels with more rigid mechanical properties, but with high permeability and water content; whereas, use of coil-like D,L backbones leads to more traditional gel systems. The use of the PPLG backbone can also be used in small quantity within a gel format to present specific peptides for cell adhesion and mobility. By extending the PPLG platform with click chemistry of amino-functional groups, we have developed several new pH responsive molecules. A unique aspect of these new amine-functionalized polypeptides is the ability to buffer, and in some cases, change solubility with degree of ionization, over biologically relevant pHs. These polymers are poly(γ-propargyl L-glutamate) (PPLG) homopolymers and poly(ethylene glycol-b-γ-propargyl L-glutamate) (PEG-b-PPLG) block copolymers substituted with various amine moieties that range in pKa and hydrophobicity. These systems can be further functionalized to target specific cells, and make unique nanoscale drug carriers for systemic delivery in applications such as targeted cancer chemotherapy.

 

Title:High Harmonic Spectroscopy of Molecules
Speaker:Professor Chang Hee Nam
Date: 1st July 2015
Time: 4.00pm to 5.30pm  
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Loh Zhi Heng
Abstract: 

High-harmonic radiation emitted from molecules in a strong laser field contains the information on molecular structure and dynamics. When multiple molecular orbitals are exposed to a strong laser field, the highest-occupied molecular orbital (HOMO) is mostly ionized and thus emits strong high-harmonic radiation containing the characteristics of HOMO. The radiation from the energetically lower-lying molecular orbital (HOMO-1) is often too weak in investigating the characteristics of the HOMO-1, necessitating special techniques to observe the radiation from the HOMO-1. We present that two-dimensional high-harmonic spectroscopy could resolve high-harmonic radiation emitted from the two highest-occupied molecular orbitals, HOMO and HOMO-1, of aligned molecules. By applying an orthogonally polarized two-color laser field consisting of the fundamental and its second harmonic fields, the characteristics attributed to the two orbitals of CO2 molecules were found to be separately imprinted in odd and even harmonics [1]. Two-dimensional high-harmonic spectroscopy could thus reveal the multi-orbital characteristics of molecules, opening a new route to investigate ultrafast molecular dynamics. [1] H. Yun, K.-M. Lee, J. H. Sung, K. T. Kim, H. T. Kim, and C. H. Nam, “Resolving multiple molecular orbitals using two-dimensional highharmonic spectroscopy,” Phys. Rev. Lett. 114, 153901 (2015).

 

Title:Intrinsic dynamics within metal organic frameworks (MOFs) for solid state ion conductor
Speaker:Professor Satoshi Horike
Date: 1st July 2015
Time: 10.45am to 12.15pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Hajime Hirao
Abstract:An emerging class of solid materials - MOF (metal organic framework) are constructed from metal ions and bridging ligand to form variety of crystal structures. Due to their inorganic-organic hybrid nature and open structure, the frameworks have dynamic modes such as libration and rotation. We are aiming to control such dynamics for solid state ionics. For example, fast proton migration (or conduction) happens if we are able to construct MOF having mobile ligands which work as proton carrier. Intrinsic dynamics of MOF structures and functions of ion conductivity will be discussed.

 

Title:Functional Metallopolymers as Precursors to Magnetic Metal Nanoparticles: Synthesis, Lithographic Patterning and Applications
Speaker:Professor Raymond Wong
Date: 30th June 2015
Time: 11.00am to 12.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Robin Chi
Abstract: 

Metal-containing polymers represent an important research field due to their combination of unique and intriguing redox, electronic, magnetic, optical, and catalytic properties and their ability to be easily processed and fabricated into thin films, fibers, and other forms. Modern technology depends on fast, reliable data processing and storage. Hard ferromagnetic (L10 -phase) FePt alloy nanoparticles (NPs) with extremely high magnetocrystalline anisotropy are considered to be one of the most promising candidates for the next generation of ultrahighdensity data storage systems. The question of how to generate ordered patterns of L10 -FePt NPs and how to transform the technology to the practical application is challenging. As these metallopolymers can be readily shaped and patterned using various lithographic techniques, they offer a convenient synthetic access to patterned arrays of metal NPs with control of their composition and density per unit area, which are crucial factors for many magnetic and electronic device applications. However, many of the most desirable properties are exhibited by metal alloy NPs rather than single-component metal NPs. In this talk, the recent advance in developing new functional metallopolymers (including bimetallic metallopolymers or blends of Fe and Pt homopolymers) as precursors to magnetic metal alloy nanoparticles and their lithographic patterning studies will be presented. These metallated polymers are promising as building blocks in high-density magnetic data storage media where the convenient and rapid patterning of magnetic NPs is highly desirable.

References: 1) K. Liu, C.-L. Ho, S. Aouba, Y.-Q. Zhao, Z.-H. Lu, S. Petrov, N. Coombs, P. Dube, H. E.Ruda, W.-Y. Wong and I. Manners, “Synthesis and Lithographic Patterning of FePt Nanoparticles using a Bimetallic Metallopolyyne Precursor”, Angew. Chem. Int. Ed., 2008, 47, 1255–1259. 2) Q. Dong, G. Li, C.-L. Ho, M. Faisal, C.-W. Leung, P. W.-T. Pong, K. Liu, B.-Z. Tang, I. Manners and W.-Y. Wong, “A Polyferroplatinyne Precursor for the Rapid Fabrication of L10 -FePt-type Bit Patterned Media by Nanoimprint Lithography”, Adv. Mater., 2012, 24, 1034−1040. 3) C.-L. Ho, S.-Y. Poon, K. Liu, C.-K. Wong, G.-L. Lu, S. Petrov, I. Manners and W.-Y. Wong, “Synthesis, Photophysics and Pyrolytic Ceramization of a Platinum-containing Poly(germylacetylene) Polymer”, J. Organomet. Chem., 2013, 744, 165–171. 4) Q. Dong, G. Li, C.-L. Ho, C.-W. Leung, P. W.-T. Pong, I. Manners and W.-Y. Wong, “Facile Generation of L10 -FePt Nanodot Arrays from a Nanopatterned Metallopolymer Blend of Iron and Platinum Homopolymers”, Adv. Funct. Mater., 2014, 24, 857–862.

 

Title:Multiplex optical quantification of microorganism in biofluids
Speaker:Professor Ramon Alvarez-Puebla
Date: 29th June 2015
Time: 2.00-3.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Ling Xing Yi
Abstract: 

Plasmonic nanostructures present unique optical properties due to the generation of strong electric fields caused by the excitation of the localized surface plasmon resonances (LSPRs). One of the main applications of such LSPRs are the so-called surface enhanced spectroscopies, mainly the surface enhanced Raman scattering (SERS). These spectroscopies have potential for the detection of single molecules under the natural environmental conditions of the analyte and thus, present a broad potential application in different (bio)fields including medicine,1 the development of new diagnostic tools,2, 3 multiplex detection and bioimaging4, 5 and high-throughput screening6 applications for drug discovery.7 Herein we will disuse about the application of these technologies to the high-throughput screening multiplex identification and recounting of microorganism in biological samples in real time.

1. R. A. Alvarez-Puebla and L. M. Liz-Marzan, Small, 2010, 6, 604-610. 2. R. A. Alvarez-Puebla, et al. Proceedings of the National Academy of Sciences of the United States of America, 2011, 108, 8157-8161. 3. L. Rodríguez-Lorenzo, R. de la Rica, R. A. Álvarez-Puebla, L. M. Liz-Marzán and M. M. Stevens, Nature Materials, 2012, 11, 604-607. 4. L. Rodriguez-Lorenzo, Z. Krpetic, S. Barbosa, R. A. Alvarez-Puebla, L. M. Liz-Marzan, I. A. Prior and M. Brust, Integrative Biology, 2011, 3, 922-926. 5. M. Sanles-Sobrido, W. Exner, L. Rodriguez-Lorenzo, B. Rodriguez-Gonzalez, M. A. Correa-Duarte, R. A. Alvarez-Puebla and L. M. Liz-Marzan, Journal of the American Chemical Society, 2009, 131, 2699-2705. 6. H. Fenniri and R. Alvarez-Puebla, Nature Chemical Biology, 2007, 3, 247-249. 7. R. Perez-Pineiro, M. A. Correa-Duarte, V. Salgueirino and R. A. Alvarez-Puebla, Nanoscale, 2012, 4, 113-116.

 

Title:Influence of Interfaces on Surface Plasmon Resonances in “Quantum-Sized” Metal Nanoparticles
Speaker:Professor Sun Yugang
Date: 29th June 2015
Time: 1.30pm to 3.00pm 
Venue:NTU SPMS MAS Executive Classroom 2
Host: Assistant Professor Zhao Yanli
Abstract: 

 

Nanoparticles made of noble metals such as silver and gold exhibit strong optical absorption due to their surface plasmon resonance (SPR) that corresponds to the collective oscillation of surface conduction electrons in response to the incident electromagnetic waves. As the nanoparticles are smaller than 20 nm (i.e., the size in the range similar to that of quantum dots), the interfaces formed on the surfaces of these noble metal nanoparticles significantly influence the nanoparticles’ SPR. For example, the monodispersed silver nanoparticles synthesized via a well-defined chemical reduction process exhibit an exceptional size-dependence of SPR peak positions: as particle size decreases from 20 nm the peaks blue-shifts but then turns over near ~12 nm and strongly red-shifts. Theoretic modeling and calculations reveal that the surface chemistry corresponding to the interactions between the capping molecules and the surface silver atoms in the nanoparticles become pronounced in determining their optical properties because the surface silver atoms represent a significant fraction of the total number of atoms in small nanoparticles. Such surface chemistry reduces the density of conduction band electrons (i.e., free electrons) in the surface layer of metal atoms, thus consequently influences the frequency-dependent dielectric constant of the metal atoms in the surface layer and the overall SPR absorption spectrum. In this presentation, a number of interfaces including the aforementioned metal/surfactant interface, metal/inorganic dielectric interface, and metal/metal interface will be discussed to highlight the importance of interface conditions on SPRs in “quantum-sized” noble metal nanoparticles. A comprehensive understanding of the relationship between interfacial coupling/chemistry and optical properties will be beneficial to exploit new applications of small colloidal metal nanoparticles, such as colorimetric sensing, electrochromic devices, surface enhanced spectroscopies, and photocatalysis.

This work was performed at the Center for Nanoscale Materials, a U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences User Facility under Contract No. DE-AC02-06CH11357.

 

 

Title:Seeding a New Kind of Garden: Synthesis of Symmetrically Stellated Bimetallic Nanocrystals
Speaker:Professor Sara Skrabalak
Date: 26th June 2015
Time: 11.00am to 12.30pm   
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Ling Xing Yi
Abstract:

Branched gold-based nanoparticles are ideal platforms for plasmon-enhanced surface spectroscopies to which the introduction of a second metal can impart multi-functionality in catalysis and chemical sensing. However, most examples of stellated nanostructures are asymmetric, with branches randomly distributed from the cores of the nanoparticles. As revealed from single particle light scattering measurements, small deviations in architecture can give rise to variable properties from one particle to the next. However, as we demonstrate in a model Au-Pd system, symmetrically branched Au/Pd nanocrystals including five-branched pentapods with D3h symmetry, 24-branched nanocrystals with Oh symmetry, 12-branched nanocrystals with Td symmetry, and eight-branched octopods and bowties with Oh and D4h symmetry can be synthesized selectively. These structures are achieved by seed-mediated co-reduction wherein the shapes of the seeds direct the number and symmetry patterns of the branches. Compositional boundaries often exist at the interfaces between the seed and overgrowth metals to provide visualization via advanced electron microscopy of the relationships between seed structure and the symmetry of branched nanocrystals. From these emerging synthetic guidelines, a route to metal dendrimers, hierarchically branched nanocrystals with threedimensional structures analogous to molecular dendrimers, is also demonstrated.

 

Title:Seeking for synthetic chemists’ initiative in glycobiology
Speaker:Professor Yukishige Ito
Date: 15th May 2015
Time: 11.00am to 12.30pm   
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Liu Xuewei
Abstract:

The fields of “Glycobiology” and “Glycotechnology” are gaining an increasing amount of attention. Glycoconjugates, such as glycoproteins, glycolipids, proteoglycans, and microbial cell-surface components, consist of glycan chains. A major part of our research has been directed at the synthesis and functional analysis of glycoconjugate oligosaccharides of various origins. Biological functions of glycoconjugate glycan chains are numerous. Most typically, these molecules exist at the cell surface and play numerous roles in cellular communication events, such as cell migration, cell-matrix and cell-cell attachment, signal transduction, microbial transfection, cancer metastasis, cell differentiation, and immune responses. They also play fundamental roles in the stabilization of glycoproteins, modulating the 3-D structure and inter- and intracellular transport of proteins. Recently, functions of glycoprotein oligosaccharides in protein quality control (protein folding, transport and degradation) have become important issues. In order to gain a precise understanding of the functions of glycan chains, access to structurally defined oligosaccharides is required. Eukaryotic cells contain a huge number of glycoproteins. Furthermore, structures of glycoprotein glycan chains are highly diverse. In many cases, glycoproteins consist of various glycoforms, which differ in the number, composition, branching, or terminal modification of glycan chains. Therefore, the isolation of a homogeneous glycoprotein with a defined structure is an extremely difficult task, unless the target protein is exceptionally abundant. Glycoprotein structures are characterized by their complexity and diversity. To clarify their functions, synthetic approaches are considered to be promising. Development of synthetic methodologies useful for efficient and facile preparation of oligosaccharides is a focal issue in carbohydrate chemistry. In light of their structural diversity, practical strategy to facilitate the synthesis of oligosaccharide is expected to be highly valuable. Glycoprotein glycans are known to play numerous biological roles, both intra- and intra-cellularly, through their interaction with various proteins such as lectins, glycosidases, and glycosyltransferases. However, their precise analysis has been hindered by structural heterogeneity of glycoproteins. This talk will summarize our recent results on 1) development of novel methods for selective formation of glycosidic linkages [1-3], 2) targetoriented as well as library oriented synthesis of glycoprotein glycans [4], 3) analysis of glycan-protein interactions in the ER using synthetic substrates [5-9], and 4) mechanistic studies on carbohydrate binding agents [10].

Reference [1] A. Ishiwata, et al., J. Am. Chem. Soc., 133, 19524-19535 (2011); J. Am. Chem. Soc., 133, 2275-2291 (2011) [2] A. Ishiwata, et al., Org. Biomol. Chem., 8, 3596-3608 (2010); Angew. Chem. Int. Ed., 53, 9812-9816 (2014) [3] H. Satoh, et al., J. Am. Chem. Soc., 133, 5610-5619 (2011); S. Manabe et al., Chem. Eur. J., 20, 124-132 (2014) [4] A. Koizumi, et al., Angew. Chem. Int. Ed., 52 7426-7431 (2013); K. Fujikawa et al., Chem Eur. J., 21, 3224-3233 (2015) [4] Y. Ito, Y. Takeda, Proc. Jpn. Acad. Ser. B, 88, 31-40 (2012) [5] K. Totani, et al., Biochemistry, 48, 2933-2940 (2009) [6] Y. Takeda et al., Glycobiology, 24, 344-350 (2014) [7] Y. Ito, et al., Sem. Dev. Cell. Biol., in press (http://dx.doi.org/10.1016/j.semcdb.2014.11.011) [8] M. Izumi, et al., J. Am. Chem. Soc., 134, 7238-7241 (2012). [9] M. Sakono, et al., Biochem. Biophys. Res. Commun., 426, 504-510 (2012) [10] Y. Nakagawa, et al., Angew. Chem. Int. Ed., 50 6084-6088 (2011); J. Am. Chem. Soc., 133, 17485-17493 (2011); Chem. Eur. J., 19, 10516- 10525 (2013)

 

Title:MULTIDIMENSIONAL OPTICAL SPECTROSCOPY WITH QUANTUM LIGHT
Speaker:Dr Konstantin E. Dorfman
Date: 11th May 2015
Time: 10.30am to 12.00pm  
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Tan Howe Siang
Abstract:The progress in quantum optics utilizes a unique photon state configuration for engineering of the ultimate light-matter interactions with relatively simple material systems. It results in a broad range of photonic applications including radiation sources, quantum communication, information, computing and nanotechnology. The development of the ultrafast multidimensional nonlinear spectroscopy that has been enabled by progress in ultrafast optical technology provides a unique tool for probing complex molecules, semiconductors, nanomaterials by classical laser light. Classical light is fundamentally limited by the frequency-time uncertainty, whereas quantum light, e.g. entangled photons have independent temporal and spectral characteristics not subjected to this uncertainty. In addition low intensity requirements for multiphoton processes make them ideally suited for minimizing damage in imaging applications. Newly developed techniques make use of the quantum nature of the field in spectroscopic applications and allow to distinguish quantum pathways of matter. I demonstrate how to probe and control the dynamics of the complex molecules using quantum light and reveal the information, which is not accessible by conventional classical photonics. As an example I investigate single and double-exciton distributions in photosynthetic reaction center manipulated by entangled light. I further show how shaped entangled light can be used for multidimensional measurements of multiexcitonic systems. Finally I will demonstrate how Stimulated Raman spectroscopy can be merged with interferometric photon counting measurements for distinguishing matter pathways in multidimensional Raman spectra.

 

Title:Discovery, design and development of new anticancer agents: from the Alps, to the shores and the deep-sea
Speaker:Dr Danielle Skropeta
Date: 8th May 2015
Time: 11.00am to 12.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Liu Xuewei
Abstract:The talk will cover Dr Skropeta's natural-product inspired research on the development of isatin-based anti-mitotic agents and their targeted delivery to tumour cells, and elaboration of the same scaffold into a series of kinase inhibitors; along with work on the development of new sugar-based peptide modifiers for applications in cancer imaging and their natural product based research on rare deep-sea sponges collected by remotely operated vehicle at depths of up to 1000 m.

 

Title:Exciton and Charge Dynamics in Organic Photovoltaics
Speaker:Professor Maxim S. Pshenichnikov
Date: 6th May 2015
Time: 2.30pm to 4.00pm   
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Tan Howe Siang
Abstract:

In modern bulk heterojunction organic solar cells (OSCs) with high loadings of strongly absorptive [70]PCBM acceptor, both donor excitation with successive electron transfer and fullerene excitation followed by hole transfer, are of equal importance for charge production. Any issues in charge separation, be that ineffective electron/hole transfer or exciton recombination due to the limited diffusion length of excitons, eventually lead to significant losses in device efficiency. Since processes of excitons photogeneration, their diffusion to the interface and consequent splitting take place at sub-ns timescales, ultrafast spectroscopy is the only tool to follow the charge generation dynamics in real time.

In this presentation, I will demonstrate how ultrafast spectroscopy can be used to obtain important information on initial exciton and charge dynamics in organic photovoltaics blends. I will focus on the following two issues: (i) exciton splitting via electron transfer, and (ii) the hole transfer process from fullerene molecules to the polymers. While understanding of the former processes provides important feedback to chemical synthesis, the latter allows for morphology characterization “on-the-fly” in functional devices.

 

Title:Werner Complexes: A New Class of Chiral Hydrogen Bond Donor Catalysts for Enantioselective Organic Reactions
Speaker:Professor John Gladysz
Date: 22nd April 2015
Time: 2.00pm to 3.30pm  
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Leong Weng Kee
Abstract:

Salts of the chiral tris(ethylenediamine)-substituted octahedral trication [Co(en)3 ] 3+ , and related species, have played important historical roles in the development of inorganic chemistry and stereochemistry. 1,2 As Werner described in 1912, the two enantiomers, commonly designated L and , can be separated by crystallization of the diastereomeric tartrate salts. 2 However, despite the low cost and ready availability of the building blocks, there have been no applications in enantioselective organic synthesis. We have found that [Co(en)3 ] 3+ and related cations can be rendered soluble in organic solvents by using lipophilic anions such as "BArf– ". 3,4 Suitably functionalized derivatives act as highly enantioselective catalysts for a variety of carbon-carbon bond forming reactions. The mechanisms involve outer sphere activation of the electrophile by hydrogen bonding to the NH moieties. Other types of metal-containing chiral hydrogen bond donors are also effective, including a chelate of the CpRuL fragment. 5,6

1. Kauffman, G. B. Coord. Chem. Rev. 1974, 12, 105-149. 2. Werner, A. Chem. Ber. 1911, 44, 1887-1898 and 1912, 45, 121-130. 3. Ganzmann, C.; Gladysz, J. A. Chem. Eur. J. 2008, 14, 5397-5400. 4. See also Ghosh, S. K.; Ojeda, A. S.; Guerrero-Leal, J.; Bhuvanesh, N.; Gladysz, J. A. Inorg. Chem. 2013, 52, 9369-9378. 5. Thomas, C.; Gladysz, J. A. ACS Catalysis 2014, 5, 1134-1138. 6. (a) Scherer, A.; Mukherjee, T.; Hampel, F.; Gladysz, J. A. Organometallics 2014, 33, 6709-6722. (b) Muk-herjee, T.; Ganzmann, C.; Bhuvanesh, N.; Gladysz, J. A. Organometallics 2014, 33, 6723-6737.

 

Title:Progress in Organocatalytic Synthesis of Useful Building Blocks
Speaker:Professor Jianwen Sun
Date: 7th April 2015
Time: 11.00am to 12.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Robin Chi
Abstract:Recent development of new organic reactions that take advantage of organic catalysts has received considerable attention. These organic catalysts (e.g., chiral Brønsted acids, bases, and N-heterocyclic carbenes) can access new modes of reactivity that may not be straightforward with metal catalysis. In this lecture, I will introduce our recent progress in the development of several families of useful organocatalytic processes for the synthesis of useful building blocks.

 

Title:FOCUS: All about electrons…
Speaker:Dr. rer. nat. Michael Merkel
Date: 6th April 2015
Time: 2.30pm to 4.00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Loh Zhi Heng
Abstract:

The talk will give a brief survey of our numerous activities on the wide spread field of applied electron physics like e-beam evaporation, e-beam welding, e-beam micro-structuring, electron spectroscopy (HAXPES), electron spin analysis, electron microscopy (PEEM, TOF-PEEM, NanoESCA, Momentum Microscopy, HAXPEEM, see refs.) and related topics. Some recent developments will be presented more in detail. FOCUS is an owner-managed German company established in 1990 with today more than 30 highly educated employees. We are selling all of our in-house developed products worldwide both to scientific and to industrial customers.

References 1. V. Feyer, M. Graus, P. Nigge, M.Wießner, R.G. Acres, C. Wiemann, C.M. Schneider, A. Schöll, and F. Reinert. Adsorption Geometry and Electronic Structure of Iron Phthalocyanine on Ag Surfaces: A LEED and Photoelectron Momentum Mapping Study. Surface Science 621, 64–68 (2014). 2. M. Wiener, D. Hauschild, C. Sauer, V. Feyer, A. Schöll, and F. Reinert. Complete Determination of Molecular Orbitals by Measurement of Phase Symmetry and Electron Density. Nature Communications 5, 4156 (2014). 3. M. Patt, C. Wiemann, N. Weber, M. Escher, A. Gloskovskii, W. Drube, M. Merkel, and C. M. Schneider. Bulk Sensitive Hard X-Ray Photoemission Electron Microscopy. Review of Scientific Instruments 85, 113704 (2014).

 

Title:Recent Developments in C-S Bond Formation
Speaker:Professor Lee Chin-Fa
Date: 27th March 2015
Time: 4.15pm to 5.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Steve Zhou
Abstract:Aryl and vinyl thioethers are important skeletons found in many fields. The transition-metalcatalyzed C-S cross-coupling reaction of thiols with aryl- and vinyl halides will be discussed. Direct C-H functionalization of arenes is an important consideration from the atom economy standpoint. C-S bond formation through the direct meta C-H functionalization of arenes with sulfur surrogate in the absence of a directing group will be also involved. In this lecture, the syntheses of thioethers and thioesters through the transition-metal-free conditions will also be introduced.

 

Title:TOWARDS ALKANE OXIDATION WITH LATE TRANSITION METAL CATALYSTS
Speaker:Dr George Britovsek
Date: 26th March 2015 
Time: 11.00am to 12.30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Jason England
Abstract: 

The selective oxidation of methane to methanol, catalysed by electrophilic late transition metals such as platinum, has attracted much interest since the first observations by Shilov and Gol’dshleger in the late 1960s. The mechanism of the overall reaction, as proposed by Shilov,[1] consists of three steps: 1) C-H activation at a Pt(II) centre generating a Pt-Me bond, 2) oxidation of the Pt(II) centre to Pt(IV) and 3) functionalisation of the methyl group via reductive elimination of methanol and regeneration of the Pt(II) complex.[2] In the original Shilov reaction, the second step was carried out by a stoichiometric Pt(IV) oxidant. As part of our studies on alternative oxidants for the Shilov reaction, we have previously reported some of our work on H2O2 oxidations.[3] We have also used O2 as the oxidant and discovered a light-driven O2 insertion into platinum(II) and palladium(II) methyl bonds to give methyl peroxo complexes (Eq. 1).[4]

Exposure to light results in the formation of dinuclear excited state complexes, which undergo rapid methyl exchange reactions.[5] In the presence of oxygen, the excited state complexes are believed to react with dioxygen to form the methyl peroxo complexes.

The methyl peroxo complexes eliminate formaldehyde to form a hydroxo platinum(II) or palladium(II) complex. These novel reactions suggest the possibility for the selective oxidation of alkanes to aldehydes, as shown in the catalytic cycle below.

References [1] L. A. Kushch, V. V. Lavrushko, Y. S. Misharin, A. P. Moravsky, A. E. Shilov, Nouv. J. Chim., 1983, 7, 729. [2] S. S. Stahl, J. A. Labinger, J. E. Bercaw, Angew. Chem. Int. Ed., 1998, 37, 2180. [3] R.A. Taylor, D.J. Law, G.J. Sunley, A.J.P. White, G.J.P. Britovsek, Chem. Commun. 2008, 2800. [4] R.A. Taylor, D.J. Law, G.J. Sunley, A.J.P. White, G.J.P. Britovsek, Angew. Chem. Int. Ed. 2009, 48, 5900. [5] A.R. Petersen, R.A. Taylor, I. Vicente-Hernández, J. Heinzer, A.J.P. White, G.J.P. Britovsek, Organometallics, 2014, 33, 1453. [6] A.R. Petersen, R.A. Taylor, I. VicenteHernández, P. R. Mallender, H. Olley, A.J.P. White, G.J.P. Britovsek.

 

Title:Developing calixarenes as antimicrobial and drug delivery platforms
Speaker:Professor Susan Matthews
Date: 13th March 2015
Time: 2.30pm to 4.00pm  
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Zhao Yanli
Abstract: 

In the last decade, much interest has been focused on the use of calixarenes for a range of biological applications, based on their ease of synthesis, tunable shape and straightforward functionalisation. This talk will focus on two aspects of our recent work in this area. This includes our fundamental studies1,2 on determining the mode of cellular uptake of dye labeled cationic calix[4]arenes, using confocal microscopy, which offer important insights into the use of such molecules as platforms for gene and drug delivery. Our recent studies3,4,5,6 on the development of new antimicrobial agents through the synthesis of a topological library of glycoclusters based on calix[4]arenes, using ‘click’ chemistry, will also be described. This library includes the best inhibitor to date for the galactose binding lectin PA-IL from Pseudomonas aeruginosa, which is implicated in host tissue recognition and adhesion and/or in biofilm formation of this organism.

References: 1 R. Lalor, H. Baillie-Johnson, C. Redshaw, S. E. Matthews, A. Mueller, J. Am. Chem. Soc. 2008, 130, 2892-2893. 2 A. Mueller, R. Lalor, C Moyano Cardaba S. E. Matthews, Cytometry: Part A, 2011, 79, 126-136 3 S. Cecioni, R. Lalor, B. Blanchard, J-P. Praly, A. Imberty, S. E. Matthews, S. Vidal, Chem. Eur. J. 2009, 13232-13240 4 D. Sicard, S. Cecioni, M. Iazykov, Y. Chevolot, S. E. Matthews, J.-P. Praly, E. Souteyrand, A. Imberty, S. Vidal, M. Phaner-Goutorbe . Chem. Commun., 2011, 9483-9845 5 Z. H. Soomro, S. Cecioni, H. Blanchard, J.-P. Praly, A. Imberty, S. Vidal, S. E. Matthews, Org. Bio. Chem. 2011, 6587-6597 6 A. M. Boukerb, A. Rousset, N. Galanos, J.-B. Méar, M. Thépaut, T. Grandjean, E. Gillon, S. Cecioni, C. Abderrahmen, K. Faure, D. Redelberger, E. Kipnis, R. Dessein, S. Havet, B. Darblade, S. E Matthews, S. de Bentzmann, B. Guéry, B. Cournoyer, A. Imberty, S. Vidal, J. Med. Chem. 2014, 57,10275-89.

 

Title:Defining biomolecular structure and function in solution and on surfaces
Speaker:Professor Andrew Abell
Date: 13th March 2015
Time: 11.00am to 12.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Roderick Bates
Abstract: The function of nature’s biomolecules is defined by their ability to adopt a well-defined shape or conformation. This seminar will discuss recent work on constraining peptides and other bio-ligands into such a geometry using some’ tricks’ from organic chemistry. The work has provided a new class of antibiotic, inhibitors of key proteases to treat important disease, new materials and biosensors, and probes to study electron transfer and other biological processes. The seminar will also consider some of our recent efforts to commercialise aspects of the research.

 

Title:Synthesis of Natural Products with Poly Cyclic System
Speaker:Professor Satoshi Yokoshima
Date: 11th March 2015
Time: 4.30pm to 6.00pm  
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Professor Loh Teck Peng
Abstract: In synthetic organic chemistry, the total syntheses of natural products have realized various methods. Because the complex structures of target molecules require well-considered synthetic strategies, they often inspire the development of novel reactions. Transformations of densely functionalized molecules provide opportunities to discover novel phenomena. Consequently, expanding synthetic organic chemistry has had a positive influence on drug development, including the construction of chemical libraries, derivatization of lead compounds, and large-scale preparation of drugs and drug candidates. Hence, we have focused on continuing our synthetic studies on natural products. In this lecture, our recent syntheses of natural products, which include lepistine and lepenine, are introduced.

 

Title:Metal-Organic Nontrivial Molecules: From Structure to Application
Speaker:Professor Ali Trabolsi
Date: 10th March 2015
Time: 11.00am to 12.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Zhao Yanli
Abstract: One of the most remarkable achievements emanating from our own research laboratory in the last three years is the discovery1 of a topological triptych composed of three non-trivial structures, a [2]catenane ([2]C), a trefoil knot (TK) and a Solomon link (SK) in a wholly synthetic molecular form, from a simple pair of chelating ligands  a diformylpyridine (DFP) and a diaminobipyridine derivative (DAB). Interestingly, the crystal structure of the TK revealed the presence of two bromide anions residing in the center of a cationic trefoil knot. The anions are held in place by at least three CHBr hydrogen bonds in the unique topological cavity of the TK. The unusual ability of the TK to host two bromide anions by rare virtue of pure CH hydrogen bonding, inspired an ongoing project where the binding affinity of the TK to anions with various sizes and shapes such as I , Br , Cl , NO2  , BF4  , ClO4  , PF6  , among others is under investigation.

 

Title:Nano-Wire Pd(III) Mott-Insulators with Strong Electron-Correlation: Bistability between Pd(II/IV) Mixed-Valence States and Pd(III) Mott-Hubbard States
Speaker:Professor Masahiro Yamashita
Date: 27th February 2015
Time: 2.30pm to 4.00pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Hajime Hirao
Abstract: 

Quasi-one-dimensional halogen-bridged Pt, Pd and Ni compounds have attracted much attention because these compounds show very interesting physical properties such as the intense charge transfer bands, luminescence with large Stokes shifts, progressive overtones of resonance Raman Spectra, mid-gap absorptions of soliton and polaron, gigantic third-order optical nonlinearity, etc. The Pt and Pd compounds take the M(II)-M(IV) mixed-valence states due to the strong electron-phonon interaction, where the bridging halogens are distorted from the midpoints between the neighboring metal ions. On the other hand, the Ni compounds take the Ni(III) Mott-Hubbard states due to the strong electron-corrlations, where the bridging halogens are located at the midpoints between the neighboring Ni ions. There are no exceptional compounds before our researches.

In my talk, I will show the three strategies to create the first examples of the Pd(III) Mott-Hubbard states as follows; (1) To use the chemical pressures of the counter-anions with the long alkyl chains such as [Pd(en)2Br](Cn -Y)2 . (2) To use Ni-Pd mixed-metal compounds, Ni1 - xPdx (chxn)2Br3 . (3) To use cyclopentanediamine as in-plane ligands in order to reduce the ligand fields, [Pd(cpn)2Br]Br2 .

In (1), the compound [Pd(en)2Br](C5 -Y)2 shows the phase transition between the Pd(II)-Pd(IV) mixed-valence states and Pd(III) Mott-Hubbard states around 205 K. In (2), the compound Ni1- xPdx (chxn)2Br3 takes the Pd(II)-Pd(IV) mixed-valence states with x > 0.9, while the compound takes the Pd(III) Mott-Hubbard states with x < 0.9. In (3), the compound [Pd(cpn)2Br]Br2 shows the phase transition between the Pd(II)-Pd(IV) mixed-valence states and Pd(III) Mott-Hubbard states with the wide temperature ranges from 200 K to 80 K. These Pd(III) Mott-Hubbard compounds are the first examples and good candidates to show the gigantic third-order optical nonlinearity, which are available for the optical communications, optical computers, etc.

[1] M. Yamashita, et al., Nature, 405, 929(2000) [2] M. Yamashita, et al., J. Am. Chem. Soc., 130, 12080(2008) [3] M. Yamashita, et al., Chem. Commun., 50, 8382(2014)

 

Title:Frontier of Quantum Molecular Spintronics Based on Single-Molecule Magnets: Toward Green IT Innovation
Speaker:Professor Masahiro Yamashita
Date: 27th February 2015
Time: 11.00am to 12.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Hajime Hirao
Abstract: 

Spintronics is a key technology in 21st century based on the freedoms of the charge, spin, as well as orbital of the electron. The MRAM systems (magnetic random access memory) by using Giant Magnetoresistance (GMR) or Tunneling Magnetoresitance (TMR) have several advantages such as no volatility of information, the high operation speed of nanoseconds, the high information memory storage density, and the low consuming electric power. Usually in these systems, the bulk or classical magnets composed of the transition metal ions are used, while in our study we will use Single-Molecule Magnets (SMMs), which are usually composed of multi-nuclear metal complexes and nano-size magnets. Moreover, SMMs show the slow magnetic relaxations due to the double-well potential defined as |D|S2 and the quantum tunneling. In our study, we hope to realize the new quantum molecular spintronics such as GMR and TMR by using SMMs. According to such a strategy, we have synthesized the conducting SMM such as [TbPc2 ]Cl0.6 , whose blocking temperature is 47K. The hysteresis is observed below 10K. This SMM shows the negative magnetoresistance below 8 K. As for the second strategy, we try to input/output one memory into/from double-decker Tb(III) SMM (TbPc2 ) by using the spin polarized STM (Scanning Tunneling Microscopy). In this research, we have observed Kondo peak by using STS (Scanning Tunneling Spectroscopy) for the first time. We have succeeded in controlling the appearance and disappearance of Kondo peak by the electron injection using STS, reversibly. This is considered as the first single-molecule memory device. 1 ) As for the third strategy, we have made the FET (Field Effect Transistor) devices of SMMs. The DyPc2 device shows the ambipolar (n- and p-type) behavior, while the TbPc2 device shows the p-type behavior. 2 ) As for the fourth strategy, we have made doping of Cs atoms onto Pc2Y, where Kondo peaks have not observed by coupling between the radical of Pc and 6s electron of Cs atom to make a single pair, while other Pc2Y sites show Kondo peak due to the radicals. As for the fifth strategy, we have succeeded to write the letters of T and U, which are the initials of Tohoku University as shown in Figure. 3-4 ) As for the sixth strategy, we have evaporated TbPc2 SMM on the magnetic Co surface, and by using the magnetic Cr tip, we have observed the GMR (200 %) for the first time. Finally, we have evaporated the Co film and TbPc2 on Au surface, and by using the magnetic Cr tip, we have observed the TMR with the double butterfly structure for the first time. 

[1] T. Komeda, M. Yamashita, et al., Nature Commun., 2, 217(2011) [2] K. Katoh, M. Yamashita, et al., J. Am. Chem. Soc., 131, 9967(2009) [3] Z.Wei-Xiong, M. Yamashita, et al., J. Am. Chem. Soc., 134, 6908(2012) [4] T. Komeda, K. Kaoth, M. Yamashita, et al., J. Am. Chem. Soc., 135, 651(2013)

 

Title:Synthetic Application of Cyclic Oxime Esters as Nitrene Precursors
Speaker:Professor Kouichi Ohe
Date: 25th February 2015
Time: 11.00am to 12.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Shunsuke Chiba
Abstract: A nitrene species is one of the intriguing active intermediates that provide easy access to nitrogen-containing compounds. Although several precursors to generate such species have been developed so far, they must be carefully treated due to their low stability. In this context, we have developed catalytic nitrene-transfer reactions using cyclic oxime esters as stable and novel nitrene precursors, which undergo oxidative addition to low-valent transition metal followed by decarboxylation to form vinylnitrene and related complexes. The recent advances of nitrene-transfer reactions in my group will be presented.

 

Title:Catalysts for asymmetric reduction
Speaker:Professor Simon Jones
Date: 13th February 2015
Time: 2.30pm to 4.00pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Dr Sumod Pullarkat
Abstract: Cost effective and efficient methods for the production of small molecule building blocks for use in medicinal and agrochemical applications remains a challenge for many academic and process chemistry groups. Safe transition from the laboratory to an industrial environment requires careful consideration of many reaction parameters, including solvent, catalyst and specialist equipment. Research from this group has examined the applicability of catalysts to effect the asymmetric reduction of prochiral C=O and C=N bonds. We have examined a number of catalyst and reduction systems, in each case looking at the potential translation from the laboratory to an industrial environment. This talk will provide an overview of the chemistry discovered to-date, demonstrating ways to access chiral alcohols and amines.

 

Title:Biomimetic Metal-Oxygen Intermediates in Dioxygen Activation Chemistry
Speaker:Professor Wonwoo Nam
Date: 13th February 2015
Time: 11.00am to 12.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Prof Xing Bengang
Abstract: 

Dioxygen is essential in life processes, and enzymes activate dioxygen to carry out a variety of biological reactions. One primary goal in biomimetic research is to elucidate structures of reactive intermediates and mechanistic details of dioxygen activation and oxygenation reactions occurring at the active sites of enzymes, by utilizing synthetic metal-oxygen complexes. A growing class of metal-oxygen complexes, such as metal–superoxo, –peroxo, –hydroperoxo, and –oxo species, have been isolated, characterized spectroscopically, and investigated in various oxygenation reactions. During the past decade, we have been studying the chemical and physical properties of various reactive intermediates in oxygenation reactions, such as high-valent iron(IV)- and manganes(V)-oxo complexes of heme and non-heme ligands in oxotransfer and C-H activation reactions, non-heme metal-peroxo complexes in nucleophilic reactions, and non-heme metal-superoxo complexes in electrophilic reactions. The effects of supporting and axial ligands on structural and spectroscopic properties and reactivities of metal-oxygen adducts have been extensively investigated as well. In this presentation, I will present our recent results on the synthesis and structural and spectroscopic characterization of mononuclear nonheme metal-dioxygen intermediates as well as their reactivities in electrophilic and nucleophilic oxidation reactions.

Some Selected Papers (1) “Redox-Inactive Metal Ions Modulate the Reactivity and Oxygen Release of a Mononuclear Nonheme Iron(III)-Peroxo Complex” Nature Chemistry 2014, 6, 934–940. (2) “Tuning Reactivity and Mechanism in Oxidation Reactions by Mononuclear Nonheme Iron(IV)-Oxo Complexes” Acc. Chem. Res. 2014, 47, 1146–1154. (3) “Mononuclear Metal-O2 Complexes Bearing Macrocyclic TMC Ligands Acc. Chem. Res. 2012, 45, 1321–1330. (4) “Structure and Reactivity of a Mononuclear Non-Haem Iron(III)-Peroxo Complex” Nature 2011, 478, 502–505. (5) “Highly Efficient Photocatalytic Oxygenation Reactions Using Water as an Oxygen Source” Nature Chemistry 2011, 3, 38–41. (6) “Crystal Structure of a Metal Ion-Bound Oxoiron(IV) Complex and Implications for Biological Electron Transfer” Nature Chemistry 2010, 2, 756–759. (7) “Geometric and Electronic Structure and Reactivity of a Mononuclear ‘Side-On’ Nickel(III)-peroxo Complex” Nature Chemistry 2009, 1, 568– 572. (8) “High-Valent Iron(IV)-Oxo Complexes of Heme and Nonheme Ligands in Oxygenation Reactions” Acc. Chem. Res. 2007, 40, 522–531. (9) “A Thiolate-Ligated Nonheme Oxoiron(IV) Complex Relevant to Cytochrome P450” Science 2005, 310, 1000–1002. (10) “Crystallographic and Spectroscopic Characterization of a Nonheme Fe(IV)=O Complex” Science 2003, 299, 1037–1039.

 

Title:Chemistry of a Rigid H-Shaped π-Scaffold
Speaker:Professor Jye-Shane Yang
Date: 10th February 2015
Time: 11.00am to 12.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Tan Choon Hong
Abstract: 

Pentiptycene is a rigid H-shaped -scaffold, containing a central phenylene ring that is sterically shielded by four peripheral phenylene rings. Such a unique structural feature has led us to explore its possible applications. For example, its paddlewheel-like shape can function as a 4-bladed molecular rotor in molecular devices such as molecular brakes, gears, and motors. The bulkiness of pentiptycene can also tune the conformation and thus the electronic properties of the resulting π-conjugated systems. The synthesis of pentiptycene derivatives relies on the central-ring prefunctionalized pentiptycene building blocks. A useful approach toward the preparation of these building blocks is the derivatization of pentiptycene quinone. In this lecture, the story of our pentiptycene chemistry, synthesis and application, will be presented with an emphasis of the design concept.

Selected references (1) Yang, J.-S.; Yan, J.-L. Chem. Commun. 2008, 1501-1512. (2) Yang, J.-S.; Yan, J.-L.; Lin, C.-K.; Chen, C.-Y.; Xie, Z.-Y.; Chen. C.-H. Angew. Chem. Inter. Ed. 2009, 48, 9936-9939 (3) Kundu, S. K.; Tan, W. S.; Yan, J.-L.; Yang, J.-S. J. Org. Chem. 2010, 75, 4640-4643. (4) Kao, C.-Y.; Hsu, Y.-T.; Lu, H.-F.; Chao, I.; Huang, S.-L.; Lin, Y.-C.; Sun, W.-T.; Yang, J.-S. J. Org. Chem. 2011, 76, 5782-92. (5) Chen, Y.-C.; Sun, W.-T.; Lu, H.-F.; Chao, I; Huang, G.-C.; Lin, Y.-C.; Huang, S.-L.; Huang, H.-H.; Lin, Y.-D.; Yang, J.-S. Chem. Eur. J. 2011, 17, 1193-1200. (6) Yang, C.-H.; Ch. Probhakar; Huang, S.-L.; Lin, Y.-C.; Tan, W. S.; Misra, N. C.; Sun, W.-T.; Yang, J.-S. Org. Lett. 2011, 13, 5632. (7) Sun, W.-T.; Huang, S.-L.; Yao, H.-H.; Chen, I-C.; Lin, Y.-C.; Yang, J.-S. Org. Lett. 2012, 14, 4154-4157. (8) Sun, W.-T.; Huang, G.-J.; Huang, S.-L.; Lin, Y.-C.; Yang, J.-S. J. Org. Chem. 2014, 79, 6321-6325. (9) Lin, C.-J.; Chen, C.-Y.; Kundu, S. K.; Yang, J.-S. Inorg. Chem. 2014, 53, 737-745. (10) Lin, C.-J.; Kundu, S. K.; Lin, C.-K.; Yang, J.-S. Chem. Eur. J. 2014, 20, 14826-14833.

 

Title:Toward an Ideal Synthesis of Bioactive Molecules Through Direct Arene Assembling Reactions
Speaker:Professor Junichiro Yamaguchi
Date: 5th February 2015
Time: 3.00pm to 4.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Shunsuke Chiba
Abstract: 

Biaryls and heterobiaryls are ubiquitous motifs in pharmaceuticals, natural products, and organic materials alike, and therefore, the construction of these scaffolds has been a topic of great importance in chemistry. Recently, C–H coupling of aromatic compounds using transition metal catalysts has garnered much attention from the synthetic chemistry community as a next-generation coupling method for constructing (hetero)biaryl motifs.[1] Although the development of new reactions and catalysts continues to evolve at a rapid pace, successful applications of this method to the synthesis of natural products and pharmaceuticals are still rare.[2] Thus, our research program has focused on synthesis-oriented methodology development in catalytic C–H coupling (direct arene–assembling reactions). As a result, more than ten new C–H coupling reactions of heteroarenes such as 1,3-azoles, indoles, pyrroles, azines and thiophenes have been developed and utilized for the rapid synthesis of bioactive molecules such as natural products and pharmaceutical candidates. Furthermore, the method of late-stage C–H coupling can be highly relevant for medicinal chemistry. In this lecture, I would like to talk our recent progress of toward an ideal synthesis of bioactive molecules through direct arene assembling.

Referecnes: 1. Yamaguchi, J.; Itami, K. “Biaryl Synthesis through Metal-Catalyzed C–H Arylation”, Metal-Catalyzed Cross-Coupling and More, Wiley–VCH, 2013, in press. 2. Yamaguchi, J.; Yamaguchi, A. D; Itami, K. Angew. Chem. Int. Ed. 2012, 51, 8960.

 

Title:Approaches to Molecular Complexity: The Strategic Implementations of Free Radicals in Natural Product Synthesis
Speaker:Professor Takehiko Yoshimitsu
Date: 5th February 2015
Time: 2.00pm to 3.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Professor Loh Teck Peng
Abstract: 

Our laboratory has been engaged in synthetic studies particularly on bioactive natural products, including antitumor alkaloids, 1 antibiotics, 2 neuroexcitatory amino acids, 3 chlorosulfolipid toxins, 4 and kinase inhibitors, 5,6 which potentially contribute to the development of medicinal chemistry and chemical biology. This presentation will discuss our recent endeavors to establish radical-based approaches to polycyclic natural products along with their biological studies towards drug development.

References 1. (a) Yoshimitsu, T.; Ino, T.; Tanaka, T. Org. Lett., 2008, 10, 5457. (b) Yoshimitsu, T.; Ino, T.; Futamura, N.; Kamon, T.; Tanaka, T. Org. Lett., 2009, 11, 3402. (c) Shigeoka, D.; Kamon, T.; Yoshimitsu, T. Beilstein. J. Org. Chem., 2013, 9, 860. Medicinal studies on agelastatin derivatives, see: (d) Li, Z.; Shigeoka, D.; Caulfield, T. R.; Kawachi, T.; Qiu, Y.; Kamon, T.; Arai, M.; Tun, H. W.; Yoshimitsu, T. Med. Chem. Commun., 2013, 4, 1093. (e) H. W. Tun, T. Yoshimitsu, D. Shigeoka, T. Kamon, Z. Li, Y. Qiu, T. R. Caulfield, Treating Brain Cancer Using Agelastatin A(AA) and Analogues Thereof, PCT Int. Appl. 2014, WO 2014059314 A1 20140417. 2. (a) Yoshimitsu, T.; Nojima, S.; Hashimoto, M.; Tanaka, T. Org. Lett., 2011, 13, 3698. (b) Moustafa, G. A. I.; Saku, Y.; Aoyama, H.; Yoshimitsu, T. Chem. Commun. 2014, 50, 15706. 3. Kamon, T.; Irifune, Y.; Tanaka, T.; Yoshimitsu, T. Org. Lett., 2011, 13, 2674. 4. (a) Yoshimitsu, T.; Fukumoto, N.; Nakatani, R.; Kojima, N.; Tanaka, T. J. Org. Chem., 2010, 75, 5425. (b) Yoshimitsu, T.; Nakatani, R.; Kobayashi, A.; Tanaka, T. Org. Lett., 2011, 13, 908. 5. (a) Yoshimitsu, T.; Nojima, S.; Hashimoto, M.; Tsukamoto, K.; Tanaka, T. Synthesis, 2009, 2963. (b) Suizu, H.; Shigeoka, D.; Aoyama, H.; Yoshimitsu, T. Org. Lett., 2015, 17, 126. 6. Moustafa, G. A. I.; Kamada, Y.; Tanaka, T.; Yoshimitsu, T. Org. Biomol. Chem., 2012, 10, 8609

 

Title:Density Corrected Density Functional Theory (DC-DFT) for Abnormal Density Functional Calculations
Speaker:Professor Eunji Sim
Date: 30th January 2015
Time: 2.30pm to 4.00pm  
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Hajime Hirao
Abstract: 

Density functional theory (DFT) is one of the most widely used electronic structure calculation methods due to its accuracy and practical computation cost. There remain challenges, however, such as anionic systems and radical systems where DFT suffers from the self-interaction error. For systematic error analysis, we decompose the energy error of any variational density functional calculation into errors contributed from the approximate functional and that from the self-consistent Korn-Sham density [1] . In most DFT calculations, the functional error dominates: however, we have found several abnormal cases where the density-driven error dominates. In particular, any selfinteraction error can be decomposed this way and many of them, while rare, turned out to be density-driven. We suggest a simple cure for these abnormal calculations, density corrected density functional theory (DC-DFT). DC-DFT is a non-variational DFT which uses more accurate density than the approximate density. One practical way to implement the method is to use the Hartree-Fock density, which has been already known to give remarkably accurate results in some cases. A small HOMO-LUMO gap in DFT calculations leads to large density-driven errors and, thus, may be used as an indicator of abnormal calculations. We discuss examples including simple two electron atom energies, electron affinities of small molecules [2] , dissociation curves, and preferred geometries of ions and radicals in solution [3] .

[1] M.-C. Kim, E. Sim and K. Burke, Phys. Rev. Lett., 111, 073003 (2013). [2] M.-C. Kim, E. Sim and K. Burke, J. Chem. Phys., 134, 171103 (2011). [3] M.-C. Kim, E. Sim and K. Burke, J. Chem. Phys., 140, 18A528 (2014).

 

Title:The New World of Organic Chemistry in Water
Speaker:Professor Shu Kobayashi
Date: 29th January 2015
Time: 2.00pm to 3.30pm   
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Shunsuke Chiba
Abstract: 

(1) Catalytic Asymmetric C-C Bond-Forming Reactions in Water

(2) Metal or Metal Hydroxide-Catalyzed Reactions in Water

(3) Unique Reactivity and Selectivity Observed in Water

(4) 40th Anniversary of the Mukaiyama Aldol Reaction

 

Title:Chemically modified oligonucleotides for therapeutic gene silencing
Speaker:Professor Jonathan Watts
Date: 16th January 2015
Time: 2.30pm to 4.00pm  
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Li Tianhu
Abstract: 

Oligonucleotide-mediated gene silencing has the potential to become a major therapeutic strategy. Clinical progress in this field has largely depended on advances in the chemistry of oligonucleotides: for example, the oligonucleotides early in clinical trials today are delivered at about 100 fold smaller doses than the chemistry of a decade ago, and yet show increased activity and specificity. We will describe several ways in which the chemistry of an oligonucleotide can influence its binding partners inside cells and thus its biological activity, focusing on results in triplet repeat disorders and asthma.

We will also discuss the development of a novel class of aptamer-polymer hybrids called AptaMIPs. Aptamers are nucleic acid species that bind targets with high affinity and specificity. By making a polymerisable aptamer, we have now been able to develop imprinted polymers with the oustanding binding properties of aptamers but the stability advantages of a polymer.

 

Title:New Adventures in Organic Chemistry: Synergistyc Catalysis and photo-organocascade reactions
Speaker:Professor Ramon Rios Torres
Date: 14th January 2015
Time: 3.30pm to 5.00pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Tan Choon Hong
Abstract: 

Recently, the quest of Asymmetric Methodologies has emerged as one of the cornerstones of organic chemistry. The synthesis of complex scaffolds with multiple stereogenic centers has become an enormous challenge for organic chemists. Moreover these new methodologies should follow the principles of Atom economy and Green Chemistry. In this lecture we will present the latest outcomes of our research efforts in these areas:

First we developed new methodologies based on the concept of Synergistic Catalysis (where two catalytic cycles are working in concert to generate a new C-C bond) to afford new N-heterocyclic scaffolds in highly stereoselective fashion.

Additionally we have developed new green procedures starting from organophotocatalytic reactions to end with new heterogenisation of catalysts in several solid supports to generate waste free reactions that fulfil the requirements of green chemistry for this new millennium.

 

Title:Predictive Design of Multifunctional Solid Catalysts
Speaker:Professor Robert Raja
Date: 14th January 2015
Time: 2.00pm to 3.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Associate Professor Leong Weng Kee
Abstract: 

The ability to devise and design multifunctional active sites at the nanoscale, by drawing on the intricate ability of enzymes to evolve singlesites with distinctive catalytic function, has prompted complimentary and concordant developments in the field of catalyst design and in situ operando spectroscopy. The choice and proximity of these multifunctional sites coupled with their propensity to modify and tailor the local-structural environment in their immediate vicinity has since instigated the predictive design of novel heterogeneous solids for targeted catalysis. By aligning the synthetic strategy with in situ spectroscopic and structural methods for probing the nature of the active site at the molecular level, we have demonstrated how these isolated single-sites can communicate with one another, at the atomic scale, to provide synergistic enhancements in catalytic activity and selectivity. These characterization tools have facilitated robust structure-property correlations to be established, which have enabled the rational design of highly active and selective catalysts for selective oxidation and acid-catalysed processes. Innovations in design-application approach have led to a more fundamental understanding of catalytic processes at the nanoscale, which has facilitated the dextrous manipulation and predictive design of redox and solid-acid sites for industrially-significant, sustainable catalytic transformations. The talk will focus on strategies for the integration and amalgamation of these developments leading to the discovery and design of novel hierarchical materials that can help overcome mass-transfer limitations and lead to the stabilisation of otherwise unstable active centres in porous architectures.

 

Title:Flexible frameworks: prediction and rational design of zeolites and framework encapsulated nanomaterials
Speaker:Dr. Asel Sartbaeva
Date: 9th January 2015
Time: 3.00pm to 4.30pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host: Assistant Professor Zhao Yanli
Abstract: 

In this talk I will present two aspects of framework studies. Firstly, I will discuss rational search for zeolites among hypothetical structures, and secondly, development of novel framework encapsulated nanomaterials.

Today synthetic zeolites are the most important catalysts in petrochemical refineries because of their high internal surface areas and catalytic and chemical properties. There have been considerable efforts to synthesize new zeolites with specific pore geometries, to add to 216 available at present. Millions of hypothetical structures have been generated on the basis of energy minimization, and there is an ongoing search for criteria capable of predicting new zeolite structures. We have recently discovered a new property of realizable zeolites – the flexibility window – which is a theoretical measure which can provide a valuable selection criterion when evaluating hypothetical zeolite framework structures as potential synthetic targets. I will show that the flexibility window is a necessary structural feature that enables zeolite synthesis.

Another application where pore geometries have a big role is design of encapsulated nanomaterials. Many alkali metals and alkali metal hydrides/amides are very strong and important reagents and catalysts in organic chemistry. Unfortunately, they are air-sensitive, pyrophoric, harmful and sometimes toxic, in short – unsafe to use in the laboratory conditions. Encapsulation of such material in abundant, not-toxic and not-reactive and open framework can lead to much safer handling and greener chemistry. We have recently produced a metal hydride nanomaterial encapsulated in silica, which retains its reactive properties, but is not pyrophoric in dry air. The success of this material can lead to new way of developing nanomaterials by encapsulating them in a protective framework for safer handling.