Seminars 2013

Title: Bimetallic Nanostructures and Their Plasmonic Properties
Speaker:Professor Jianfang Wang
Date:13 December 2013
Time:3:30pm – 5:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Ling Xing Yi  
Abstract:Plasmonic metal nanocrystals have received much attention owing to their attractive plasmonic features. Their plasmon resonance wavelengths can be synthetically varied. Their absorption/scattering cross sections normalized against their physical sizes are larger than those of atoms, ions, molecules, and semiconductor nanocrystals. Upon resonant excitation, they can concentrate light into near-field regions close to the metal surface. Moreover, the local density of photonic states around metal nanocrystals are largely enhanced around their plasmon wavelengths. These plasmonic features have enabled a number of applications with metal nanocrystals in a wide range of areas, such as imaging, sensing, nanomedicine, enhancement of linear and nonlinear optical signals, optics and optoelectronics. Bimetallic nanostructures combine together two different metals. They can provide properties and functions that are impossible from monometallic nanocrystals. In this presentation, I will focus on our recent studies of bimetallic nanostructures, including their preparation, plasmonic properties, and applications.
Title: Dissecting Cell Death by Means of Chemical Genetics and Natural Product
Speaker:Professor Xiaoguang Le
Date:13 December 2013
Time:2:00pm – 3:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng 
Abstract:

Cell death is a universal and fundamental cellular process. Apoptosis and necrosis are two common features of genetically programmed cell death that play vital roles in development and maintaining homeostasis in metazoans. Dysfunction of the regulated machinery may lead to carcinogenesis or autoimmune diseases. On the other hand, inappropriate death of essential cells may also lead to organ dysfunction or even death, such as ischemia-reperfusion injury and neurodegenerative disorders. Our laboratory has been using bioactive small molecules (either natural products or non-natural compounds) in a genetic-like approach to probe fundamental biological processes like cell death. Herein, we would like to report our recent research endeavor on the development of a novel small molecule probe necrosulfonamide (NSA) to dissecting programmed necrosis,1 as well as using a complex natural product ainsliatrimer A 2 and a new and robust thiol-vinyl ether/ortho-quinone methide bioorthogonal ligation (TQ ligation)3 to study a noncanonical cell death. In this respect, novel small molecule modulators of cell death may pave the way for the development of potentially therapeutic treatment for the related intractable human diseases.

References: 1. Sun, L.; Wang, H.; Wang, Z.; He, S.; Chen, S.; Liao, D.; Wang, L.; Yan, J.; Liu, W.; Lei, X.*; Wang, X.* Cell 2012, 148, 213-227. (News stories describing this work were highlighted in Chem. & Eng. News 2012, 5, 40; Nature China 2012, February 1; Asian Scientist 2012, January31; and Nature Reviews Molecular Cell Biology, 2012, Feb. 8) 2. a) Li, C.; Dian, L.; Zhang, W.; Lei, X.* J. Am. Chem. Soc. 2012, 134, 12414-12417; b) Li, C.; Dong, T.; Dian, L.; Zhang, W.; Lei, X.* Chem. Sci. 2013, 4, 1163-1167 3. Li, Q.; Dong, T.; Liu, X.; Lei, X.* J. Am. Chem. Soc. 2013, 135, 4996-4999. (News story describing this work was highlighted in Chem. & Eng. News 2013, 14, 37)

Title: Functional π Materials with Rigidity and Flexibility
Speaker:Professor Shigehiro Yamaguchi
Date:13 December 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba 
Abstract:

Construction of new p-conjugated skeletons is crucial for pursuing photo/electronic functions of organic molecules. In the molecular designs, rigidity and flexibility of the skeletons are fundamental concerns. In the development of boron-containing p-conjugated materials, we have recently proposed that a rigid structural constraint is a potent strategy for the stabilization of Lewis acidic tri-coordinate boron compounds. 1 On the basis of this concept, we have synthesized a series of planarized organoboron materials, including boron-doped nanographenes 1, with high stabilities. 2 On the other hand, the control of the flexibility or dynamic motion of p-skeleton leads to production of interesting properties. 3 In particular, the control of the structural change in the excited state enables us to produce intriguing fluorescent molecular systems 2. 4 In this lecture, our recent results along these two lines will be discussed.

References: 1. (a) Zhou, Z.; Wakamiya, A.; Kushida, T.; Yamaguchi, S. J. Am. Chem. Soc. 2012, 134, 4529. (b) Kushida, T.; Zhou, Z.; Wakamiya, A.; Yamaguchi, S. Chem. Commun. 2012, 48, 10715. (c) Kushida, T.; Yamaguchi, S. Angew. Chem. Int. Ed. 2013, 52, 8054. 2. (a) Saito, S.; Matsuo, K.; Yamaguchi, S. J. Am. Chem. Soc. 2012, 134, 9130. (b) Dou, C.; Saito, S.; Matsuo, K.; Hisaki, I.; Yamaguchi, S. Angew. Chem. Int. Ed. 2012, 51, 12206. (c) Dou, C.; Saito, S.; Yamaguchi, S. J. Am. Chem. Soc. 2013, 135, 9346. 3. (a) Mouri, K.; Saito, S.; Yamaguchi, S. Angew. Chem. Int. Ed. 2012, 51, 5971. (b) Mouri, K.; Saito, S.; Hisaki, I.; Yamaguchi, S. Chem. Sci. 2013, 4, 4465. 4. Yuan, C.; Saito, S.; Camacho, C.; Irle, S.; Hisaki, I.; Yamaguchi, S. J. Am. Chem. Soc. 2013, 135, 8842.

Title: Surface and Interfacial Chemistry of Noble Metal Nanocrystals
Speaker:Professor Nanfeng Zheng
Date:9 December 2013
Time:3:00pm – 4:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Chen Hongyu
Abstract:

The surface and interface of metal nanoparticles play important roles in many of their catalysis and bio-applications. It however remains challenging to characterize and precisely control the surface and interfacial structures of metal nanoparticles. To tackle such a challenge and thus optimize the properties of nanoparticles, much of our research effort has been directed towards the controlled synthesis, structure characterizations and structure-properties relationship studies of noble metal nanocrystals. In this talk, I will provide an overview of our recent research in the surface and interfacial structure control of metal nanocrystals (Figure 1). I will first discuss how small but strong adsorbates control the surface structure of Pd/Pt nanocrystals. For example, CO molecules behave differently in the controlled synthesis of Pd and Pt nanostructures. CO prefers to adsorb on Pd {111} surface to facilitate the growth of ultrathin Pd nanosheets and tetrapod/tetrahedral nanocrystals having {111} as the main exposure surface. An important intermediate, [Pd2 (-CO)2Cl4 ] 2- , has been recently identified for the synthesis of surface-clean Pd nanosheets. But for Pt, the preferential adsorption of CO on Pt {100} induces the formation of Pt nanocubes. The strong adsorption of amines on Pt stepped sites help the formation of high-index {411} faceted Pt nanocrystals displaying an excellent electrocatalytic activity. Besides the surface structure control and their applications of the shapecontrolled metal nanocrystals, the control over the interfacial structure of metal nanocrystals and nanoclusters for the optimization of their catalytic properties will be presented in the talk.
Title: From antennae to reaction centers and back. What do antenna function, non-photochemical quenching, and reaction center function have in common?
Speaker:Alfred R. Holzwarth
Date:2 December 2013
Time:10:30am – 12:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Howe Siang
Abstract:

Comparing pigment arrangements in the many available structures of photosynthetic antenna complexes with those appearing in reaction centers, one notices that very similar arrangements of the same pigments have been chosen to function either as efficient light harvesters or as centers of ultrafast charge separation. It thus becomes obvious that the detailed pigment arrangement is not the main factor controlling excited state processes. Rather it is the surrounding protein that actually decides about the specific functioning in a particular case, i.e. whether a pigment cluster functions as an antenna or as a reaction center. Thus the protein – or more generally the “environment” - takes the role of a “smart responsive matrix”. At present we do not understand well the governing factors at a molecular level. However the design of efficient artificial antenna and charge separation units – with or without proteins – requires a deeper understanding and control of these environmental effects, i.e. the properties of the “responsive matrix”.

Recent studies on non-photochemical quenching (NPQ) in antenna complexes have turned out to provide fundamental insights into these environmental effects controlling the fate of the excited state energy. A common denominator of most NPQ quenching processes is the ultrafast formation of a chlorophyll-chlorophyll charge transfer state, by a mechanism that in many details operates in the same way as the “normal” processes of ultrafast photosynthetic charge separation occurring in reaction centers. Astounding and unexpected parallels between those - at first glance unrelated - processes of NPQ and of reaction center function have been found. The talk will discuss the general principles governing the role of the protein in switching between light-harvesting, non-photochemical quenching, and productive ultrafast charge separation in reaction centers.

Title: Polydentate Ligands Effects in Palladium Cross-Coupling/ C–H Activation Catalysis
Speaker:Professor Jean-Cyrille Hierso
Date:2 December 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

The development of polydentate ligands based on ferrocene platform has driven progress in homogeneous catalysis. [1-3] Catalyst longevity and ultra-low catalyst loadings have been used to reach high turnover numbers (TONs > 10,000). These performances were based on original multidentarity effects, which are now used to develop very efficient methods for palladium-catalysed C–C, C–N and C–O cross-couplings, thus direct C–H and O–H functionalization of demanding substrates including organic chlorides are feasible. The features of robust, air-stable polyphosphine auxiliaries and their performances in recent low loading palladium-catalyzed reactions in direct arylation and etherification reactions of heteroaromatics will be detailed. [4,5,6] Mechanisms in oxidative addition and reductive elimination (electroanalysis, kinetics, DFT modeling) have revealed net differences with traditional monophosphine ligands that will be described. [6-10]

Reference 1. (a) Hierso, J.-C.; Fihri, A.; Amardeil, R.; Meunier, P.; Doucet, H.; Santelli, M.; Ivanov V. V. Org. Lett. 2004, 6, 3473 ; (b) Ivanov, V. V.; Hierso, J.-C.; Amardeil, R.; Meunier, P. Organometallics 2006, 25, 989. 2. (a) Hierso, J.-C.; Fihri, A.; Ivanov, V. V.; Hanquet, B.; Pirio, N.; Donnadieu, B.; Rebière, B.; Amardeil, R.; Meunier, P. J. Am. Chem. Soc. 2004, 126, 11077; (b) Mom, S.; Beaupérin, M.; Roy, D.; Royer, S.; Amardeil, R.; Cattey, H.; Doucet, H.; Hierso, J.-C. Inorg. Chem. 2011, 50, 11592. 3. Doucet, H.; Hierso, J.-C. Angew. Chem. Int. Ed. Engl. 2007, 46, 834. 4. Roy, D.; Mom, S.; Beaupérin, M.; Doucet, H.; Hierso, J.-C. Angew. Chem. Int. Ed. 2010, 49, 6650. 5. Roy, D.; Mom, S.; Lucas, D.; Cattey, H.; Hierso, J.-C.; Doucet, H. Chem.−Eur. J. 2011, 17, 6453. 6. Platon, M.; Cui, L.; Mom, S.; Richard, P.; Saeys, M.; Hierso, J.-C. Adv. Synth. Catal. 2011, 353, 3403. 7. Evrard, D.; Lucas, D.; Mugnier, Y.; Meunier, P.; Hierso, J.-C. Organometallics 2008, 27, 2643. 8. Zinovyeva, V. A.; Luo, C.-H.; Fournier, S.; Devillers, C. H.; Cattey, H.; Doucet, H.; Hierso, J.-C.; Lucas, D. Chem.−Eur. J. 2011, 17, 9901. 9. Roy, D.; Mom, S.; Royer, S.; Lucas, D.; H.; Doucet, H.; Hierso, J.-C. ACS Catalysis, 2012, 2, 1033. 10. Zinovyeva, V. A.; Mom, S.; Fournier, S.; Devillers, C. H.; Cattey, H.; Doucet, H.; Hierso, J.-C.; Lucas, D. Inorg. Chem., 2013, 52, 11923.

Title: Pacman macrocycles: New complexes, reactions, and catalysts for sustainable chemistry
Speaker:Dr Jason Love
Date:29 November 2013
Time:2:00pm – 3:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Leong Weng Kee
Abstract:

Molecular inorganic chemistry provides insight into and solutions for some of the major scientific challenges faced by 21st century societies. This presentation will provide an overview of sustainable inorganic chemistry, with particular focus towards the design and development of new Schiff-base pyrrole ‘Pacman’ macrocycles as controlled platforms for new reactions, catalysis, and supramolecular chemistry. The efficacy of binuclear cobalt Pacman complexes as redox catalysts for the selective reduction of oxygen to water will be highlighted, and the transformation of carbon dioxide by these compounds will be described. The confined chemical space defined by these macrocycles is also exploited in new and fundamental oxo-chemistry of the uranyl dication, along with the synthesis of hydroxycubanes, size-limited through macrocyclic encapsulation.

Leading references: Feature articles Chem. Commun., 2009, 3145; Chem. Commun., 2012, 48, 1392; Chem. Commun., 2013, 49, 1891; O2 reduction Angew. Chem. Int. Ed., 2007, 46, 584; Dalton Trans., 2012, 41, 65; encapsulation J. Am. Chem. Soc., 2011, 137, 7320; uranyl chemistry Nature, 2008, 451, 315; Nat. Chem., 2010, 2, 1056; Nat. Chem., 2012, 4, 221; J. Am. Chem. Soc., 2013, 135, 3841.

Title: Control of the excitation energy flow in plant photosynthetic membranes by protein interactions
Speaker:Professor Petar Lambrev
Date:21 November 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Howe Siang
Abstract: Proteins represent up to 80% of the chloroplast thylakoid membrane and by way of mo-lecular recognition create a three-dimensional hierarchical structure with multiple levels of organization – pigment-protein complexes assemble into supercomplexes, which form supercomplex arrays, which are stacked to from grana [1]. Absorbed light energy is trans-ferred via a network of light-harvesting pigmentprotein complexes to the photosynthetic reaction centres. Interactions of light-harvesting complex II (LHCII) – the most abundant protein – mediate the grana formation and the efficient long-distance energy transfer. We have studied the energetic connectivity in isolated LHCII aggregates and native thylakoid membranes and Photosystem II-enriched membranes by picosecond time-resolved fluorescence and kinetic modeling and found out that during the excited state’s lifetime the energy can migrate over tens of complexes [2]. Thus, the overall kinetics of photosynthetic charge separation is not limited by energy transfer in the antenna. The regulation of light-harvesting and protection against photodamage under conditions of excess irradiation is also controlled by interactions between LHCIIs forming oligomers. These interactions are signified by far-red fluorescence emission observed in vitro [3] and in vivo [4]. Protein interactions in LHCII are reported with great sensitivity by circular dichroism (CD) spectroscopy. By comparing the CD spectra of solubilized LHCII with those of LHCII aggregates and native and artificial protein-lipid membranes we demonstrate the importance of protein interactions in the organization of LHCII in the native membrane [5] and identify specific CD spectral signatures. The CD spectral changes occurring upon changing the LHCII microenvironment may be related to actual structural changes with the help of a novel technique, anisotropic CD spectroscopy [6].
Title: Publishing in Materials Science (and how to maximize your success!)
Speaker:Dr Mary Farrell
Date:21 November 2013
Time:10:30am – 12:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Chen Hongyu
Abstract: A seminar on “Publishing in Materials Science (and how to maximize your success!)” will be offered at NTU on November 21st 2013. The speaker will introduce the materials science portfolio of journals offered by Wiley; a number of the flagship journals include Advanced Materials, Advanced Functional Materials and Small. The role that scientific journals play in an Online Age will be presented and the Editorial Process with focus on peer review will be discussed. Important topics such as choosing the right journal to submit to and increasing the visibility of published content will be presented from an editor’s point of view.
Title: R&D at Chemical Companies: What Mitsui Chemicals Is Doing
Speaker:Dr Terunori Fujita
Date:19 November 2013
Time:3:00pm–5:00pm
Venue:NTU SPMS LT 2
Host:Associate Professor Shunsuke Chiba
Title: Chemistry inside and Applications of Molecular Containers
Speaker:Professor Werner Nau
Date:15 November 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract:

Molecular container compounds of the calixarene, cyclodextrin, and cucurbituril type have been extensively employed in two main areas in the solution phase: supramolecular catalysis and molecular recognition. The former is of prominent interest for mimicking biocatalysis by carrying out chemical reactions in confined nanospace,1 while the latter bears enormous potential for practical applications, namely sensing and separation technologies.2 Figure 1. Structures of the molecular containers predominantly used in our work.

We will describe our own work in both areas. In catalysis, we will elaborate on examples involving the use of macrocycles, in particular cucurbiturils, in metal ion and proton-assisted (photo)reactions.3,4 Recently, we have been able to realize chemical reactions inside molecular containers in the gas phase.5 In molecular recognition, we will describe new strategies for exploiting the rather unselective binding6,7 of molecular containers, calixarenes and cucurbiturils, in combination with fluorescent dyes, for sensitively and specifically monitoring biochemical processes in complex systems.8-14

References 1 Dong, Z. Y.; Luo, Q.; Liu, J. Q. Chem. Soc. Rev. 2012, 41, 7890–7908. 2 Applications of Supramolecular Chemistry; Schneider, H.J.; Ed.; CRC Press: Boca Raton, FL, 2012. 3 Klöck, C. Dsouza R. N., Nau, W. M. Org. Lett. 2009, 11, 2595–2598. 4 Koner, A. L.; Márquez, C.; Dickman, M. H.; Nau, W. M. Angew. Chem. Int. Ed. 2011, 50, 545–548. 5 Lee, T.-C.; Kalenius, E.; Lazar, A. I.; Assaf, K. I.; Kuhnert, N.; Grün, C. H.; Jänis, J.; Scherman, O. A.; Nau, W. M. Nature Chem. 2013, 5, 376–382. 6 a) Biedermann, F.; Uzunova, V. D.; Scherman, O. A.; Nau, W. M.; De Simone, A. J. Am. Chem. Soc. 2012, 134, 15318–15323. b) El-Sheshtawy, H. S.; Bassil, B. S.; Assaf, K. I.; Kortz, U.; Nau, W. M. J. Am. Chem. Soc. 2012, 134, 19935−19941. 8 Hennig, A.; Bakirci, H.; Nau, W. M. Nat. Methods 2007, 4, 629-632. 9 Nau, W. M.; Ghale, G.; Hennig, A.; Bailey, D. M. J. Am. Chem. Soc. 2009, 131, 11558–11570. 10 Ghale, G.; Ramalingam, V.; Urbach, A. R.; Nau, W. M. J. Am. Chem. Soc. 2011, 133, 7528–7535. 11 Guo, D.-S.; Uzunova, V. D.; Su, X.; Liu, Y.; Nau, W. M. Chem. Sci., 2011, 2, 1722–1734. 12 Florea, M.; Nau, W. M. Angew. Chem. Int. Ed. 2011, 50, 9338–9342. 13 Dsouza, R. N.; Pischel, U.; Nau, W. M. Chem. Rev. 2011, 111, 7941–7980. 14 Dsouza, R. N.; Hennig, A.; Nau, W. M. Chem. Eur. J. 2012, 18, 3444–3459.

Title: Recent Studies on the Total Synthesis of Natural Products and Related Systems
Speaker:Professor Martin Banwell
Date:14 November 2013
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 Chiral Sulfur-based Simple Olefins as New Promising Ligands for Asymmetric Catalysis
Speaker:Professor Ming-Hua Xu
Date:12 November 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Robin Chi
Abstract:

Over the past decades, the demands of efficient chiral ligands for asymmetric catalysis are rapidly increasing in the field of synthetic organic chemistry and pharmaceutical chemistry. Despite the considerable efforts, however, there have been limited successes on rational design of simple chiral skeletons capable of efficient asymmetric catalysis. Recently, we reported our discovery of a novel class of chiral sulfur-based olefin ligands (SOLs) bearing exceptionally simple frameworks (Figure 1) and their successful application in a series of rhodium-catalyzed asymmetric addition to C=C, C=O and C=N double bonds. In this presentation, the development of these simple chiral ligands as well as their great performances in asymmetric transformations will be described.

Title: Organocascade Synthesis of Substituted Carbocycles
Speaker:Professor Chen Kwunmin
Date:30 October 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract:

The structural motifs of carbocycles are important in many biologically active and pharmaceutical products. The stereoselective formation of carbocyclic ring systems with multiple stereogenic centers from its acyclic precursors has attracted substantial attention for its usefulness in the total synthesis of natural products. The development of organocatalyst in asymmetric reactions has attracted much attention in recent years as the organocatalytic systems are generally nontoxic, highly selective, efficient, environmentally friendly, and stable under aerobic and aqueous conditions. On the other hand, organocascade reaction has been studied and has proven to be effective in constructing functionalized substituted carbocycles. Central to the organocascade process is the identification of suitable Michael acceptors. Several electron deficient alkenes have been employed in organocascade reactions that include enones, enals, nitroalkenes and others. In this presentation, I will discuss the use of -L-diphenylprolinol trimethylsilyl ether to catalyze organocascade reaction that involve different nucleophiles and electrophiles. The fully substituted dispirocyclohexanes that bear two all-carbon quaternary centers were obtained. Interestingly, when racemic nitroallylic acetate (I) were used in the organocascade reactions, a kinetic resolution phenomena was observed. The KR reaction proceeded smoothly to give the products with excellent stereoselectivities via an interesting SN2’ process. The KR is a traditional approach to prepare chiral nonracemic substrates. The KR strategy that involves the generation of new stereogenic centers and functionalization of the more reactive enantiomeric substrate are synthetic attractive. The less reactive enantiomeric nitroallylic acetate was recovered with high optical purity. In addition, a highly efficient three-component, organocascade kinetic resolution has been demonstrated by treating indole with acrolein and racemic nitroallylic acetates in the presence of diphenylprolinol trimethylsilyl ether. The mechanistic explanation of the cascade reaction will be discussed. The use of nitroallylic acetate (I) for the synthesis of substituted pyrroles/furans will be presented if time permitted.

Title: Organocascade Synthesis of Substituted Carbocycles
Speaker:Professor Chen Kwunmin
Date:30 October 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract:

The structural motifs of carbocycles are important in many biologically active and pharmaceutical products. The stereoselective formation of carbocyclic ring systems with multiple stereogenic centers from its acyclic precursors has attracted substantial attention for its usefulness in the total synthesis of natural products. The development of organocatalyst in asymmetric reactions has attracted much attention in recent years as the organocatalytic systems are generally nontoxic, highly selective, efficient, environmentally friendly, and stable under aerobic and aqueous conditions. On the other hand, organocascade reaction has been studied and has proven to be effective in constructing functionalized substituted carbocycles. Central to the organocascade process is the identification of suitable Michael acceptors. Several electron deficient alkenes have been employed in organocascade reactions that include enones, enals, nitroalkenes and others. In this presentation, I will discuss the use of -L-diphenylprolinol trimethylsilyl ether to catalyze organocascade reaction that involve different nucleophiles and electrophiles. The fully substituted dispirocyclohexanes that bear two all-carbon quaternary centers were obtained. Interestingly, when racemic nitroallylic acetate (I) were used in the organocascade reactions, a kinetic resolution phenomena was observed. The KR reaction proceeded smoothly to give the products with excellent stereoselectivities via an interesting SN2’ process. The KR is a traditional approach to prepare chiral nonracemic substrates. The KR strategy that involves the generation of new stereogenic centers and functionalization of the more reactive enantiomeric substrate are synthetic attractive. The less reactive enantiomeric nitroallylic acetate was recovered with high optical purity. In addition, a highly efficient three-component, organocascade kinetic resolution has been demonstrated by treating indole with acrolein and racemic nitroallylic acetates in the presence of diphenylprolinol trimethylsilyl ether. The mechanistic explanation of the cascade reaction will be discussed. The use of nitroallylic acetate (I) for the synthesis of substituted pyrroles/furans will be presented if time permitted.

Title: Gallium nitride - thin films and nanoparticles
Speaker:Professor Zdenek Sofer
Date:24 October 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Martin Pumera
Abstract:

Gallium nitride materials are at the forefront of nanoelectronic research due to their importance for optoelectronic and spintronics. In this presentation the methods of synthesis and characterizations of GaN based nanomaterials will be presented. The doping of GaN in the form of thin films and nanoparticles will be discussed. Transition metal and rare earth doped GaN exhibit ferromagnetic behavior persisting at temperatures over 300 K and offer possible applications for future spintronics devices. The presented materials were synthesized in the form of thin films using CVD techniques and ion implantations. Bulk material in the form of nanoparticles was synthesized using rapid thermal decomposition of complex precursors in ammonia atmosphere. Prepared materials were characterized using Raman and photoluminescence spectroscopy, X-ray diffraction. Magnetic properties were investigated with SQUID magnetometer and Faraday balance in the temperature range of 4 K – 800 K.

Title: Convergent and Enantioselective Total Synthesis of (-)-Amphidinolide O and (-)-Amphidinolide P
Speaker:Professor Lee Duck Hyung
Date:22 October 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

Amphidinolide series have attracted much attention of the synthetic community because of their biogenetically unusual structural features and cytotoxic activities against various cancer cell lines.1 For example, two novel macrolides such as mphidinolides O (1) and P (2) shows in vitro cytotoxicity against murine lymphoma L1210 and human epidermoid carcinoma KB cells (IC50 values: 1.7 and 3.6 mg/ml for 1 and 1.6 and 5.8 mg/ml for 2).2 Amphidinolide O (1) and P (2) possess analogous 15-membered ring structures with one epoxide (C8 -C9 ), one double bond (C12-C13), one exocyclic double bond at C5 and one six-ring bridged hemiacetal group, and differ only at C11 position (carbonyl for 1 and exo-methylene group for 2).2 So far, two research groups completed the total synthesis of 2, 3 and total synthesis of 1 was not reported yet. We describe herein the convergent approach for the first enantioselective synthesis of 1 as well as the structure confirmation of the absolute stereochemistry of 1, and its conversion to natural (+)-2 as well. The key reactions are enantioselecive Brown allylation, anti-aldol reaction, syn-aldol reaction, Grubbs olefin metathesis for the C8 -C9 double bond formation, stereoselective epoxidation of the resulting C8 -C9 double bond, and two Peterson olefination of -hydroxysilane for the introduction of two exocyclic double bonds at C5 and C11.

References 1. a) Kobayashi, J.; Ishibashi, M., Chem. Rev. 1993, 93, 1753-1769; b) Chakraborty, T. K., Das, S., Curr. Med. Chem.: Anti-Cancer Agents 2001, 1, 131-149; c) Kobayashi, J.; Tsuda, M., Nat. Prod. Rep. 2004, 21, 77-93; d) Kobayashi, J.; Kubota, T., J. Nat. Prod. 2007, 70, 451-460, e) Morris, J. C.; Phillips, A. J., Nat. Prod. Rep. 2009, 26, 245-65; f) Fuerstner, A., Isr. J. Chem. 2011, 51, 329-345. 2. Ishibashi, M.; Takahashi, M.; Kobayashi, J., J. Org. Chem. 1995, 60, 6062-6066. 3. a) Williams, D. R.; Myers, B. J.; Mi, L., Org. Lett. 2000, 2, 945-948; b) Chakraborty, T. K.; Das, S., Tetrahedron Lett. 2001, 42, 3387-3390; c) Trost, B. M.; Papillon, J. P. N., J. Am. Chem. Soc. 2004, 126, 13618-13619; d) Trost, B. M.; Papillon, J. P. N.; Nussbaumer, T., J. Am. Chem. Soc. 2005, 127, 17921-17937.

Title: Synthesis of carbocyclic and heterocyclic β-amino acid derivatives
Speaker:Professor Norbert De Kimpe
Date:18 October 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract:

β-Amino acids and their derivatives received considerable attention in recent years because of their substantial bioactivities in several domains, e.g. pharmaceutical and agrochemical areas. Therefore, carbocyclic as well as heterocyclic β-amino acid derivatives take a prominent place in synthetic organic chemistry. Various novel routes towards these β-amino acid derivatives (three-, four-, five- and sixmembered rings of various kinds) will be discussed with focus to diastereoselectivities and the chiral synthesis of novel classes of these compounds. Attention will be paid to mechanistic explanations and the importance of bioactivities. Some of the novel amino acid derivatives are built into peptides in relation to conformational studies of foldamers.

Title: Complex Assemblies of Nanoscale Building Blocks and Their Applications
Speaker:Professor Yu Shu-Hong
Date:3 October 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract:

The huge diversity of hierarchical micro-/nano- rigid structures existing in biological systems is increasingly becoming a source of inspiration of materials scientists and engineers to create next generation advanced functional materials. In this lecture, I will report several facile synthetic protocols for one-pot controlled synthesis of several kinds of unique nanoscale building blocks, which include ultrathin nanowires, nanoplates, and magnetic nanoparticles, conducting nanocables, and carbon-based nanostructures. Then, we discuss how to assemble these nanoscale building blocks into 2D ordered assemblies, 3D macroscopic assemblies, and their functionalities. Recent advances have emphasized that it is possible to access a variety of high quality hybrid materials with tunable mechanical property and multifunctionalities. These macroscopic-scale assemblies based on nanoscale building blocks should find broad applications in different fields.

Title: Science behind the use of essential oils in health-related issues
Speaker:Professor Lin Hsueh-Kung
Date:2 October 2013
Time:11:30am – 1:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Shao Fangwei
Abstract:

Distillation is a physical separation process, but not a chemical reaction. Distillation methods have been used to extract biologically active compounds from plants and herbs for thousands of years. Although herbal distillates, or essential oils, contain abundant highly volatile, aromatic compounds and are mainly used for aromatherapy, we demonstrated that these distillates retain active biological compounds that can be useful and beneficial for a variety of health-related conditions. We will describe potential usages of essential oils prepared from various plants in cancer, wound healing, infectious diseases, and Alzheimer’s disease with possible mechanisms of action. In addition, we will discuss how to introduce the advances in experimental models and modern scientific technologies to the traditional chemical-free extraction methods. With the use of approved scientific methodologies, appropriate pre-clinical models, and rigorous clinical validations, essential oils might represent cleaner and safer therapeutic agents for treating a variety of disorders and diseases.

Title: Nickel N-Heterocyclic Carbene Chemistry: C–H Activation Reactions and Catalysis
Speaker:Professor Michael Chetcuti
Date:17 September 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Dragoslav Vidovic
Abstract:

This presentation describes recent advances in the chemistry and the catalytic reactions of half-sandwich nickel complexes that bear Nheterocyclic carbenes (NHCs) as ligands. The syntheses and structures of neutral and cationic complexes of general formula [CpNi(NHC)X] (X =Cp, Cp*, X = Cl, I and [CpNi(NHC)S]+ (S = CH 3 CN, acetone), respectively, will be discussed. The talk will then focus on three facets of this research: 1) The use of these complexes as catalysts for the Miyaura-Suzuki coupling of aryl halides. 2) The base assisted C–H activation reactions of α-C-H bonds of ketones and of nitriles that are carried out by these complexes. – Intramolecular C–H activation of the α-C-H bonds of nitriles, that are attached to the NHC ligand as a side-arm, leads to new nickelacycles; acetone undergoes a remarkable double C-H activation reaction. 3) The recent use of Ni-NHC half-sandwich complexes as catalysts for the hydrosilylation of aldehydes and ketones (via probable CpNi(NHC) hydride intermediates) and for ketone arylation reactions.

Recent representative publications: - Facile displacement of η 5 -¬‐cyclopentadienyl ligand from half -¬‐sandwich alkyl,NHC –nickel complexes: an original route to robust cis-¬‐C,C-¬‐nickel square planar complexes. Chem. Commun., 2013, 49, 6424 . - Hydrosilylation of Aldehydes and Ketones Catalyzed by an N-¬‐Heterocyclic Carbene-¬‐Nickel Hydride Complex under Mild Conditions. Adv. Syn. Cat., 2012, 354, 2619. - Synthesis and Catalytic Activity in Suzuki Coupling of Nickel Complexes Bearing n -¬‐Butyl-¬‐ and Triethoxysilylpropyl-¬Substituted NHC Ligands: Toward the Heterogenization of Molecular Catalysts. Organometallics, 2012, 7, 2829. - Intramolecular Nitrile C–H Bond Activation in Nickel NHC Complexes: A Route to New Nickelacycles. Organometallics , 2011, 30, 3400. - C-¬‐H Activation of Acetonitrile at Nickel: Ligand Flip and Conversion of N-¬‐Bound Acetonitrile into a C -¬ Bound Cyanomethyl Ligand. J. Am. Chem. Soc., 2010, 132 , 13588.

Title: Total Synthesis of Guanidine-Containing Natural Products
Speaker:Professor Toshio Nishikawa
Date:10 September 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract:

Many guanidine-containing natural products have been isolated from nature, in particular from marine sources. Among them, tetrodotoxin (TTX) and saxitoxin (STX) are the most famous as a toxic principle of puffer fish intoxication and a paralytic selfish toxin, respectively. Both natural toxins exert their potent toxicities through specific blockage of sodium ion influx through voltage-gated sodium channel proteins on neuronal cell membrane. Due to the unique biological properties, these compounds have been employed as important biochemical tools in neurophysiological experimentation.

Our research group has devoted to investigate efficient and flexible synthetic methodologies of these guanidine-containing natural toxins in order to develop new sodium channel blockers on the basis of natural products1,2 . Chiriquitoxin (CHTX, 1) isolated from a dart frog living in Costa Rica is the most structurally complex analog of tetrodotoxin. This natural toxin was synthesized from a newly designed intermediate for the synthesis of diverse tetrodotoxin derivatives. Decarbamoyl---saxitoxinol (2) isolated from cyanobacterium, Lyngyba wollei, is a naturally occurring analog of saxitoxin. We have developed a bromocation-triggered cascade cyclization of guanidino-acetylene compound to construct the cyclic guanidine framework of saxitoxin. The cascade cyclization enables us to synthesize crambescin B carboxylic acid 3, an other guanidine-containing natural product isolated from theMediterranean sponge Crambe crambe.

Title: Efficient Transition Metal Catalysis with Two Chamber Reactors
Speaker:Professor Troels Skrydstrup
Date:5 September 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

In this talk, I will present our latest work dealing with transition metal catalyzed carbonylation reactions aimed at the development of new techniques and new synthetic transformations using carbon monoxide. In particular, I will focus my presentation on the use of carbon monoxide releasing molecules (CORMs) in combination with a recently designed two-chamber reactor, which provide a convenient and simple set-up for performing carbonylation reactions without having to consider the hazards associated with this toxic diatomic molecule. The talk will also cover various aspects including carbonylation reactions employing stoichiometric and substoichiometric carbon monoxide, the development of new carbonylation transformations, as well as new methods for isotope labeling. Furthermore, I will present ongoing work with other small molecular weight gases.

Relevant References 1. Hermange, P.; Lindhardt, A. T.; Taaning, R. H.; Bjerglund, K.; Lupp, D.; Skrydstrup, T. J. Am. Chem. Soc. 2011, 133, 6061. 2. Friis, S. D.; Taaning, R. H.; Lindhardt, A. T.; Skrydstrup, T. J. Am. Chem. Soc. 2011, 133, 18114. 3. Hermange, P.; Gøgsig, T. M.; Lindhardt, A. T.; Taaning, R. H.; Skrydstrup, T. Org. Lett. 2011, 13, 2444. 4. Nielsen, D. U.; Taaning, R. H.; Lindhardt, A. T.; Gøgsig, T. M.; Skrydstrup, T. Org. Lett. 2011, 13, 4454. 5. Xin, Z.; Gøgsig, T. M.; Lindhardt, A. T.; Skrydstrup, T. Org. Lett 2012, 14, 284. 6. Gøgsig, T. M.; Taaning, R. H.; Lindhardt, A. T.; Skrydstrup, T. Angew. Chem. Int. Ed. 2012, 51, 798. 7. Bjerglund, K.; Lindhardt, A. T.; Skrydstrup, T. J. Org. Chem. 2012, 77, 3793. 8. Gøgsig, T. M.; Nielsen, D. U.; Lindhardt, A. T.; Skrydstrup, T. Org. Lett. 2012, 14, 2536. 9. Burhardt, M. N.; Taaning, R.; Nielsen, N. C.; Skrydstrup, T. J. Org. Chem. 2012, 77, 5357. 10. Nielsen, D. U.; Neumann, K.; Taaning, R. H.; Lindhardt, A. T.; Modvig, A.; Skrydstrup, T. J. Org. Chem. 2012, 77, 6155. 11. J. Label. Compd. Radiopharm. 2012, 55, 411. 12. Burhardt, M. N.; Taaning, R.; Nielsen, N. C.; Skrydstrup, T. Org. Lett. 2013, 15, 948. 13. Korsager, S.; Taaning, R. H.; Skrydstrup, T. J. Am. Chem. Soc. 2013, 135, 2891. 14. Friis, S.; Andersen, T. L.; Skrydstrup, T. Org. Lett. 2013, 15, 1378. 15. Korsager, S.; Taaning, R. H.; Skrydstrup, T. J. Org. Chem. 2013, 78, 6112. 16. Korsager, S.; Taaning, R. H.; Skrydstrup, T. Angew. Chem. Int. Ed. 2013, 52, ASAP.

Title: Poly(ethylene glycol) : an eco-friendly solvent in metal-catalyzed reactions
Speaker:Dr Frédéric Lamaty
Date:3 September 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

Poly(ethylene glycol) (PEG) has been widely used for biomedical applications especially in the field of drug-delivery. 1 A few years ago, supported synthesis on a soluble polymer such as PEG has been developed for the preparation of libraries of small organic molecules. 2 More recently, the use of PEG as support and solvent was extended to metal-catalyzed reactions. 3 We will present herein examples of metal-catalyzed reactions including Heck reaction, 4 Sonogashira 5 and Ullmann 6 couplings, Ring-Closing Metathesis 7 and Platinum- and Gold-catalyzed cycloisomerizations 8 where the different roles of poly(ethylene glycol) will be highlighted.

References : 1. Poly(ethylene glycol) Chemistry and Biological Applications, Harris J. M., Zalipsky, S. Eds ; A. C. S., Washington 1997. 2. Gravert, D. J.; Janda, K. D. Chem. Rev. 1997, 97, 489. 3. Colacino, E.; Martinez, J.; Lamaty, F.; Patrikeeva, L. S.; Khemchyan, L. L.; Ananikov, V. P.; Beletskaya, I. P. Coord. Chem. Rev. 2012, 256, 2893. 4. a. Ribière, P.; Declerck, V.; Nédellec, Y.; Yadav-Bhatnagar, N.; Martinez, J.; Lamaty, F. Tetrahedron 2006, 62, 10456. b. Declerck, V.; Ribière, P.; Nédellec,Y.; Allouchi, H.; Martinez, J.; Lamaty, F. Eur. J. Org. Chem. 2007, 201. c. Declerck, V.; Martinez, J.; Lamaty, F. SYNLETT 2006, 3029. Declerck, V.; Colacino, E.; Bantreil, X.; Martinez, J.; Lamaty, F. Chem. Commun. 2012, 48, 11778. 5. Colacino, E. ; Daïch, L., Martinez, J. ; Lamaty, F. SYNLETT 2007, 1279. 6. Colacino, E.; Villebrun, L.; Martinez, J.; Lamaty, F.Tetrahedron 2010, 66, 3730. 7. Bantreil, X.; Sidi-Ykhlef, M.; Aringhieri, L.; Colacino, E.; Martinez, J.; Lamaty, F. J. Catal. 2012, 294, 113. 8. a. Spina, R.; Colacino, E.; Gabriele, B.; Salerno, G.; Martinez, J. ; Lamaty, F. J. Org. Chem. 2013, 78, 2698. b. Spina, R. ; Martinez, J. ; Colacino, E. ; Lamaty, F. Chem. Eur. J. 2013, 19, 3817.

Title: PLAYING WITH CAVITAND-BASED PHOSPHINES : from supramolecular chelators to "oschelating" ligands
Speaker:Professor Dominique Matt
Date:29 August 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Francois Mathey
Abstract:

How can a molecular cavity influence the properties of an appended metal centre? To answer this question, we have investigated the properties of transition metal complexes derived from podands based on conical cavities, notably calix[4]arenes, resorcinarenes, and cyclodextrins. Metallocavitands with coordination sites directed towards the interior of the generic cavity provide valuable systems for studying host–guest complexation processes, their enhanced strength of metal-ion binding allowing for regioselective catalysis in a confined environment, and stabilisation of coordination complexes of unusual forms. 1 They may also act as shape-selective catalysts. 2 Where cavitands have exo-oriented podand arms, the intrinsic dynamics of the cavity can dramatically modify metal chelation behaviour and consequently the catalytic properties of the resulting complexes. 3 This presentation will focus on the use of some cavity-shaped mono- and di-phosphines in coordination chemistry and catalysis.

1Gramage-Doria, R.; Armspach, D.; Matt, D. Coord. Chem. Rev. 2013, 257, 776; S. Sameni, C. Jeunesse, D. Matt, L. Toupet, Chem. Eur. J. 2010, 15, 10446 2 Sémeril, D.; Jeunesse, C.; Matt, D.; Toupet, L. Angew. Chem. Int. Ed., 2006, 45, 5810; Sémeril, D. ; Matt, D.; Toupet, L. Chem. Eur. J. 2008, 14, 7144; Monnereau, L.; Sémeril, D. ; Matt, D.; Toupet, L.; Mota, A. Adv. Synth. Catal. 2009, 351 , 1383 3 Lejeune, M.; Sémeril, D.; Jeunesse, C.; Matt, D.; Peruch, F.; Lutz, P.; Ricard, L. Chemistry. Eur. J. 2004, 21, 5354; Gramage-Doria, R.; Armspach, D.; Matt, D.; Toupet, L. Angew. Chem. 2011, 50, 1554.

Title: Nature Inspired Drug Discovery and Development of Antibiotics: Alpha-Mangostin Derived Peptidomimics and in vivo Evaluation
Speaker:Dr Liu Shouping
Date:28 August 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Dragoslav Vidovic
Abstract:

Methicillin-resistance Staphylococcus aureus (MRSA) is a predominant source of infections associated with the blood, skin and soft-tissue. In our series of studies, alpha-mangostin, a natural xanthone, which was extracted and purified from pericarp of Garcinia mangostana, has shown good activity against Gram-positive bacteria, direct interactions of α-mangostin with the bacterial membrane are responsible for the rapid concentration-dependent membrane disruption and bactericidal action; however, it has low selectivity between bacteria and mammalian cells, and less action against Gram-negative organisms [1]. A new family of xanthone derivatives was designed using alphamangostin-based peptidomimics to mimick the topology of cationic antimicrobial peptides. AM-0016 showed the most potent antimicrobial activity amongst the series of semi-synthetic alpha-mangostin based dicationic molecules. AM-0016 has broad spectrum antimicrobial activity with improved potency against 15 isolates of MRSA with MIC99 in the range of 0.39-1.56 μg/ml (0.59-2.35 μM), no in vivo cytotoxicity at 50 μg/ml on corneal wound healing, hemolytic activity with HC50 of 20 μg/ml tested with rabbit red blood cells, and increased selectivity index of 25-100. AM-0016 exhibited rapid in vitro bactericidal activity (3-log reduction within 10-20 minutes). In a multistep (20 passage) resistance selection study using MRSA DM21455 (source: eye), Enterococcus faecalis ATCC29212 and VISA, AM-0016 showed less than a 4-fold increase in MIC. [2] Biophysical studies together with molecular dynamics demonstrated that the amphiphilic AM-0016 was a membrane targeting antimicrobial against MRSA, disrupting bacteria membrane leading to leakage of intracellular contents within 20-30 minutes.[2] New lead compounds AM-052 and AM-218 shows excellent selectivity and in vivo activity with potential for topical and systemic application [3]. The design principle and approach provided a powerful platform for design of membrane targeting antibiotics by fine tuning the hemolytic and antimicrobial activities of xanthone based peptidomimics with potentials for topical and even systemic application to treat the infection caused by MRSA.

Reference 1.Koh JJ, Qiu S, Zou H, Lakshminarayanan R, Li J, Zhou X, Tang C, Saraswathi P, Verma C, Tan DT, Tan AL, Liu SP, Beuerman RW., Rapid bactericidal action of alpha-mangostin against MRSA as an outcome of membrane targeting, Biochim Biophys Acta. 2013 Feb; 1828(2):834- 44. 2.Zou H, Koh JJ, Li J, Qiu S, Aung TT, Lin H, Lakshminarayanan R, Dai X, Tang C, Lim FH, Zhou L, Tan AL, Verma C, Tan DT, Chan HS, Saraswathi P, Cao D, Liu SP, Beuerman RW., Design and synthesis of amphiphilic xanthone-based, membrane-targeting antimicrobials with improved membrane selectivity, J Med Chem. 2013 Mar 28; 56(6):2359-73. 3.Koh JJ, Lin SM, Aung TT, Zou H, Liu SP, Beuerman RW, et al, Naturally Occurring Xanthone-based Amphiphilic Peptidomimetic with Multicationic Nature: Towards Therapeutic Potential for MRSA Infection, manuscript in preparation.

Title: Asymmetric Hydrogenation of Imines and N-Containing Heteroaromatics
Speaker:Professor Fan Qing-Hua
Date:28 August 2013
Time:4:00pm – 5:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract:

Homogeneous asymmetric hydrogenation has been established as one of the most versatile and powerful tools for the preparation of a wide range of enantiomerically pure compounds in organic synthesis. Despite great efforts made in this field, asymmetric hydrogenation of imines, particularly nitrogen-containing heteroaromatic compounds, remains a major challenge. 1 In this talk, I will report our recent results on asymmetric hydrogenation of heteroaromatic compounds and imines using immobilized chiral Ir/phosphorus ligand/I 2 catalytic systems, 2 such as dendritic Ir(BINAP) catalyst (Figure 1), or using phosphine-free chiral cationic Ru- and Ir-diamine catalysts (Figure 2).3 In both cases, excellent reactivity and enantioselectivity have been achieved in the hydrogenation of quinolines, quinoxalines, cyclic imines and so on, providing a facile accessto chiral N-heterocycles.

References: [1] Xie, J. H.; Zhu, S. F.; Zhou, Q. L. Chem. Rev. 2011, 111, 1713. Zhou, Y. G. Acc. Chem. Res. 2007, 40, 1357. [2] Fan, Q. H.; Li, Y. M.; Chan, A. S. C. Chem. Rev. 2002, 102, 3385. Wang, Z. J.; Deng, G. J.; Li, Y.; He, Y. M.; Tang, W. J.; Fan, Q. H. Org. Lett. 2007, 9, 1243. Xu, L.; Lam, K. H.; Ji, J.; Wu, J.; Fan, Q. H.; Lo W. H.H.; Chan, A. S. Chem. Commun. 2005, 1390. Tang, W.; Xu, L. J.; Fan, Q. H.; Wang, J.; Fan, B.; Zhou, Z.; Lam, K. H.; Chan, A. S. C. Angew. Chem. Int. Ed. 2009, 48, 9135. [3] Zhou, H.; Li, Z.; Wang, Z.; Wang, T.; Xu, L.; He, Y.; Fan, Q.-H.; Pan, J.; Gu, L.; Chan, A. S. C. Angew. Chem., Int. Ed. 2008, 47, 8464. Wang, T.; Zhuo, L.; Li, Z.; Chen, F.; Ding, Z.; He, Y.; Fan, Q.-H.; Xiang, J.; Yu, Z.-X.; Chan, A. S. C. J. Am. Chem. Soc. 2011, 133, 9878. Qin, J.; Chen, F.; Ding, Z.; He, Y.; Xu, L.; Fan, Q.-H. Org. Lett. 2011, 13, 6568. Chen, F.; Wang, T.; He, Y.; Ding, Z.; Li, Z.; Xu, L.; Fan, Q.-H. Chem. Eur. J. 2011, 17, 1109. Chen, F.; Ding, Z.; Qin, J.; Wang, T.; He, Y.; Fan, Q.-H. Org. Lett. 2011, 13, 4348. Ding, Z.; Chen, F.; Qing, J.; He, Y.; Fan, Q.-H. Angew. Chem. Int. Ed. 2012, 51, 5706. Wang, T.; Chen, F.; Qing, J.; He, Y.; Fan, Q.-H. Angew. Chem. Int. Ed. 2013, 52, DOI: 10.1002/anie.201301830.

Title: Recent Progress in the Chemistry of Low-coordinated Heavier Group 14 Element Compounds
Speaker:Professor Norihiro Tokitoh
Date:23 August 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Rei Kinjo
Abstract:

Recent decades have witnessed a remarkable progress in the chemistry of multiply bonded species of heavier group 14 elements, and a variety of stable examples have been synthe¬sized and isolated for metallenes, dimetallenes, and metallaaromatic species. More recently, even triply bonded species (dimetallynes) have also been isolated as stable com¬pounds. We have succeeded in the synthesis and isolation of novel function¬alized disile¬nes 1a, 1 3a, 2 and 4 3 having ferrocenyl, bromo, and trimethylsilylethynyl groups as substituents by taking advantage of kinetic stabilization afforded by 2,46-tri¬iso¬pro¬pylphenyl (Tip) and 2,6-bis[bis(trime¬thyl¬silyl)methyl]-4- [tris(trimethylsilyl)¬methyl]¬¬phe¬nyl (Bbt) groups. Fur¬ther¬¬more, 1,2-dibromo¬disilene (3a) was found to be a good pre¬cur¬sor of disilyne (2a). 2 As re¬lated systems, bis(ruthenocenyl)disilene (1b) 4 , 1,2-di¬bromo¬di¬ger¬mene (3b), 5 and diger¬myne (2b) 5 were also syn¬the¬sized. The isolation of 1a,b and 2a should be of great interest from the standpoints of novel d-π con¬jugated disilenes and an un¬pre¬cedented carbon-substituted disilyne, respectively.

In this lecture, the molecular struc¬tures, unique reactivities, and some physical pro¬perties of the newly obtained low-coordinated organosilicon and organogermanium com¬pounds will be described. 6,7 In addition, attempted synthesis of a Ge=Ge bridged [2]ferrocenophane derivative will also be described.

1) Sasamori, T.; Yuasa, A.; Hosoi, Y.; Furukawa, Y.; Tokitoh, N. Organometallics 2008, 27, 3325-3327. 2) Sasamori, T.; Hironaka, K.; Sugiyama, Y.; Takagi, N.; Nagase, S.; Hosoi, Y.; Furukawa, Y.; Tokitoh, N. J. Am. Chem. Soc. 2008, 130, 13856- 13857. 3) Sato, T.; Mizuhata, Y.; Tokitoh, N. Chem. Commun. 2010, 46, 4402-4404. 4) Yuasa, A.; Sasamori, T.; Hosoi, Y.; Furukawa, Y.; Tokitoh, N. Bull. Chem. Soc. Jpn. 2009, 82, 793-805. 5) Sugiyama, Y.; Sasamori, T.; Hosoi, Y.; Furukawa, Y.; Takagi, N.; Nagase, S.; Tokitoh, N. J. Am. Chem. Soc. 2006, 128, 1023-1031. 6) a) Sasamori, T.; Han, J. S.; Hironaka, K.; Takagi, N.; Nagase, S.;. Tokitoh, N. Pure Appl. Chem. 2010, 82, 603-612. b) Han, J. S.; Sasamori, T.; Mizuhata, Y.; Tokitoh, N. Dalton Trans., 2010, 39, 9238-9240. 7) Sasamori, T.; Miyamoto, H.; Sakai, H.; Furukawa, Y.; Tokitoh, N. Organometallics 2012, 31, 3904.

Title: Recent Progress in the Chemistry of Low-coordinated Heavier Group 14 Element Compounds
Speaker:Professor Norihiro Tokitoh
Date:23 August 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Rei Kinjo
Abstract:

Recent decades have witnessed a remarkable progress in the chemistry of multiply bonded species of heavier group 14 elements, and a variety of stable examples have been synthe¬sized and isolated for metallenes, dimetallenes, and metallaaromatic species. More recently, even triply bonded species (dimetallynes) have also been isolated as stable com¬pounds. We have succeeded in the synthesis and isolation of novel function¬alized disile¬nes 1a, 1 3a, 2 and 4 3 having ferrocenyl, bromo, and trimethylsilylethynyl groups as substituents by taking advantage of kinetic stabilization afforded by 2,46-tri¬iso¬pro¬pylphenyl (Tip) and 2,6-bis[bis(trime¬thyl¬silyl)methyl]-4- [tris(trimethylsilyl)¬methyl]¬¬phe¬nyl (Bbt) groups. Fur¬ther¬¬more, 1,2-dibromo¬disilene (3a) was found to be a good pre¬cur¬sor of disilyne (2a). 2 As re¬lated systems, bis(ruthenocenyl)disilene (1b) 4 , 1,2-di¬bromo¬di¬ger¬mene (3b), 5 and diger¬myne (2b) 5 were also syn¬the¬sized. The isolation of 1a,b and 2a should be of great interest from the standpoints of novel d-π con¬jugated disilenes and an un¬pre¬cedented carbon-substituted disilyne, respectively.

In this lecture, the molecular struc¬tures, unique reactivities, and some physical pro¬perties of the newly obtained low-coordinated organosilicon and organogermanium com¬pounds will be described. 6,7 In addition, attempted synthesis of a Ge=Ge bridged [2]ferrocenophane derivative will also be described.

1) Sasamori, T.; Yuasa, A.; Hosoi, Y.; Furukawa, Y.; Tokitoh, N. Organometallics 2008, 27, 3325-3327. 2) Sasamori, T.; Hironaka, K.; Sugiyama, Y.; Takagi, N.; Nagase, S.; Hosoi, Y.; Furukawa, Y.; Tokitoh, N. J. Am. Chem. Soc. 2008, 130, 13856- 13857. 3) Sato, T.; Mizuhata, Y.; Tokitoh, N. Chem. Commun. 2010, 46, 4402-4404. 4) Yuasa, A.; Sasamori, T.; Hosoi, Y.; Furukawa, Y.; Tokitoh, N. Bull. Chem. Soc. Jpn. 2009, 82, 793-805. 5) Sugiyama, Y.; Sasamori, T.; Hosoi, Y.; Furukawa, Y.; Takagi, N.; Nagase, S.; Tokitoh, N. J. Am. Chem. Soc. 2006, 128, 1023-1031. 6) a) Sasamori, T.; Han, J. S.; Hironaka, K.; Takagi, N.; Nagase, S.;. Tokitoh, N. Pure Appl. Chem. 2010, 82, 603-612. b) Han, J. S.; Sasamori, T.; Mizuhata, Y.; Tokitoh, N. Dalton Trans., 2010, 39, 9238-9240. 7) Sasamori, T.; Miyamoto, H.; Sakai, H.; Furukawa, Y.; Tokitoh, N. Organometallics 2012, 31, 3904.

Title: Organometallics for Energy Conversion in Organic Solar Cells and OLEDs
Speaker:Professor Raymond Wong Wai Yeung
Date:22 August 2013
Time:4:00pm – 5:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Robin Chi
Abstract:

Organometallic molecules have become a field of intense activities in the optoelectronic research. They hold great promise as versatile functional materials for use in energy interconversions. These include systems where light is transformed into electricity and vice versa. This keynote lecture highlights the recent progress in the advances of numerous functional organometallic complexes and polymers with tunable photofunctional and electronic traits. Focus is placed on examining their potential as efficient emitters in light-emitting applications and semiconductors in photovoltaic cells for solar power generation. The strategies based on structural modifications of the organic groups to tune the emission and photovoltaic properties of these materials will be presented and discussed.

References: (1) W.-Y. Wong, X.-Z. Wang, Z. He, A. B. Djurišić, C.-T. Yip, K.-Y. Cheung, H. Wang, C. S. K. Mak, W.-K. Chan, Nat. Mater. 2007, 6, 521. (2) W.-Y. Wong, X.-Z. Wang, Z. He, K.-K. Chan, A. B. Djurišić, K.-Y. Cheung, C.-T. Yip, A. M.-C. Ng, Y. Y. Xi, C. S. K. Mak, W.-K. Chan, J. Am. Chem. Soc. 2007, 129, 14372. (3) W.-Y. Wong, C.-L. Ho, Z.-Q. Gao, B.-X. Mi, C.-H. Chen, K.-W. Cheah and Z. Lin, Angew. Chem. Int. Ed., 2006, 45, 7800. (4) G.-J. Zhou, W.-Y. Wong, B. Yao, Z.-Y. Xie and L.-X. Wang, Angew. Chem. Int. Ed. 2007, 46, 1149. (5) W.-Y. Wong and C.-L. Ho, C.-L. J. Mater. Chem., (Feature article) 2009, 19, 4457. (6) W.-Y. Wong and C.-L. Ho, Acc. Chem. Res., 2010, 43, 1246. (7) J. Zou, H. Wu, C.-S. Lam, C. Wang, J. Zhu, S. Hu, C. Zhong, C.-L. Ho, G.-J. Zhou, H. Wu, W.C.H. Choy, J. Peng, Y. Cao and W.-Y. Wong, Adv. Mater., 2011, 23, 2976. (8) B. Zhang, G. Tan, C.-S. Lam, B. Yao, C.-L. Ho, L. Liu, Z. Xie, W.-Y. Wong, J. Ding and L. Wang, Adv. Mater., 2012, 24, 1873.

Title: From Angewandte Chemie through Chemistry–An Asian Journal to the Asian Journal of Organic Chemistry
Speaker:Dr Peter Goelitz
Date:22 August 2013
Time:3:15pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Choon Hong
Abstract:

1. Angewandte Chemie

2. Impact Factor Mania

3. Chemistry–An Asian Journal

4. Open Access: Manna or Dilemma?

5. Asian Journal of Organic Chemistry

Title: Polymerizing Goblins and Brimstone For Energy Applications
Speaker:Professor Jeffrey Pyun
Date:22 August 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Chen Hongyu
Abstract:We will present our recent efforts in the polymerization of unconventional monomers to prepare novel polymeric and nanocomposite materials. We will discuss our recent efforts the polymerization of a novel class of polymer-nanoparticle hybrid materials on dipolar cobalt nanoparticles, which were used as “colloidal monomers” in a process termed Colloidal Polymerization. From this process, we have been able to synthesis electroactive cobalt oxide nanowires and heterostructured nanocomposites with either noble metal, or semiconductor inclusions. We will discuss our recent efforts on the synthesis and characterization of these materials along with relevance to photocatalysis for water splitting and solar hydrogen generation. In the area of electrochemical energy storage, we will discuss our recent efforts on the polymerization of elemental sulfur to prepare novel polymeric and nanocomposite materials which we are exploring for utilization in next generation Li-S batteries.
Title: Scientific publishing and communicating chemistry
Speaker:Dr Stuart Cantrill
Date:21 August 2013
Time:3:00pm–4:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Title: Abiological Self-Assembly: Predesigned Metallacycles and Metallacages via Coordination
Speaker:Professor Peter Stang
Date:21 August 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Ling Xing Yi
Abstract:

The use of just two types of building blocks, linear and angular, in conjunction with symmetry considerations allows the rational design of a wide range of metallocyclic polygons and polyhedra via the coordination motif. 1-3 We have used this approach to self-assemble a variety of 2D supramolecular polygons such as triangles, rectangles, squares, hexagons, etc. as well as a number of 3D supramolecular polyhedra: truncated tetrahedra, triginal prisms, cubooctahedra 4 and dodecahedra. 5 An example of the methodology is illustrated in Figure 1. More recently we have functionalized these rigid supramolecular scaffolds with different electroactive, host-guest, dendritic (Figure 2), and hydrophobic/hydrophilic moieties and have investigated the properties of these multifunctionalized supramolecular species. 6 Additionally, we have begun to explore the self-assembly of 2D polygons and 3D polyhedra on a variety of surfaces with the aim of developing their potential to be used in device settings. 7 These novel, supramolecular ensembles are characterized by physical and spectral means. The design strategy, formation, characterization and potential uses of these novel metallocyclic assemblies will be discussed, along with our recent results in crystal engineering.

1. S.R. Seidel, P.J. Stang, Acc. Chem. Res., 35, 972-983 (2002). 2. S. Leininger, B. Olenyuk, P. J. Stang, Chem. Rev., 100, 853-908 (2000) . 3. P. J. Stang, B. Olenyuk, Acc. Chem. Res., 20, 502-518 (1997). 4. B. Olenyuk, J. A. Whiteford, A. Fechtenkötter, P. J. Stang, Nature, 398, 796-799 (1999). 5. B. Olenyuk, M. D. Levin, J. A. Whiteford, J. E. Shield, P. J. Stang, J. Am. Chem. Soc., 121, 10434-10435 (1999). 6. B.H. Northrop, H.B. Yang, P.J. Stang, Chem. Comm. 5896-5908 (2008). 7. S.S. Li; B.H. Northrop, Q.H. Yuan, L.J. Wan, P.J. Stang, Accounts, Chem. Res., 42, 249-259 (2009) .

Title: Electrophilic Alkynylation of Olefins and Annulation Reactions of Strained Rings
Speaker:Professor Jerome Waser
Date:19 August 2013
Time:3:00pm – 4:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

The use of organic molecules of increasing complexity is one of the major motors of progress in multiple fields of fundamental and applied science, such as chemical biology, drug discovery or organic materials. To answer these needs, it is crucial to develop new reactions for a fast access into molecular complexity. Our group makes use of the power of catalysis to develop new reactions based on the exceptional reactivity of electrophilic acetylenes and aminocyclopropanes. Acetylenes: 1 The triple bond is a versatile functional group in organic chemistry, material sciences and chemical biology. Most alkynetransfer reactions have been limited to the nucleophilic addition of acetylides to electrophiles. Electrophilic alkynylation methods give access to structurally different acetylenes. Our group has introduced EthynylBenziodoXolone (EBX) hypervalent iodine reagents for direct alkyne-transfer to C=C bonds. The use of a palladium(II) catalyst combined with EBX reagents led to the first intramolecular oxy- and aminoalkynylation of olefins for the synthesis of lactones and lactamss. 1a On the other hand, a palladium(0) catalyst together with alkynyl bromides could be used to access tetrahydrofurans and pyrrolidines starting from alcohols and amines. 1b-c Nitrogen-Substituted Small Rings: 2 Activation of cyclopropanes or cyclobutanes with an amino and a carbonyl group led to exceptional reactivity, both in cyclization and annulation reactions. Selective cyclization on the carbon or nitrogen of indole heterocycles allowed the synthesis of the alkaloids aspidospermidine and goniomitine. 2a Using Phthalimido-substituted cyclopropanes together with iron or tin catalysts, a highly diastereoselective and enantiospecific [3+2] annulation reaction with enol ethers and carbonyls gave access to multi-substituted cyclopentyl- and tetrahydrofuryl amines, key structural elements of both DNA and bioactive compounds. 2b-c Recently, a new iron-catalyzed [2+2] cycloaddition reaction between alkylidene malonates and enimides was also developed to access aminocyclobutanes, setting the bases for an analogous [4+2] process. 2d

(1) (a) Nicolai, S.; Piemontesi, C.; Waser, J., Angew. Chem., Int. Ed. 2011, 50, 4680. (b) Nicolai, S.; Waser, J., Org. Lett. 2011, 13, 6324. (c) Nicolai, S.; Sedigh-Zadeh, R.; Waser, J., J. Org. Chem. 2013, 78, 3783. (2) (a) De Simone, F.; Gertsch, J.; Waser, J., Angew. Chem., Int. Ed. 2010, 49, 5767. (b) de Nanteuil, F.; Waser, J., Angew. Chem., Int. Ed. 2011, 50, 12075. (c) Benfatti, F.; de Nanteuil, F.; Waser, J., Org. Lett. 2012, 14, 386. (d) de Nanteuil, F.; Waser, J., Angew. Chem., Int. Ed. 2013, 52, ASAP: DOI: 10.1002/anie.201303803.

Title: Electrophilic Alkynylation of Olefins and Annulation Reactions of Strained Rings
Speaker:Professor Jerome Waser
Date:19 August 2013
Time:3:00pm – 4:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

The use of organic molecules of increasing complexity is one of the major motors of progress in multiple fields of fundamental and applied science, such as chemical biology, drug discovery or organic materials. To answer these needs, it is crucial to develop new reactions for a fast access into molecular complexity. Our group makes use of the power of catalysis to develop new reactions based on the exceptional reactivity of electrophilic acetylenes and aminocyclopropanes. Acetylenes: 1 The triple bond is a versatile functional group in organic chemistry, material sciences and chemical biology. Most alkynetransfer reactions have been limited to the nucleophilic addition of acetylides to electrophiles. Electrophilic alkynylation methods give access to structurally different acetylenes. Our group has introduced EthynylBenziodoXolone (EBX) hypervalent iodine reagents for direct alkyne-transfer to C=C bonds. The use of a palladium(II) catalyst combined with EBX reagents led to the first intramolecular oxy- and aminoalkynylation of olefins for the synthesis of lactones and lactamss. 1a On the other hand, a palladium(0) catalyst together with alkynyl bromides could be used to access tetrahydrofurans and pyrrolidines starting from alcohols and amines. 1b-c Nitrogen-Substituted Small Rings: 2 Activation of cyclopropanes or cyclobutanes with an amino and a carbonyl group led to exceptional reactivity, both in cyclization and annulation reactions. Selective cyclization on the carbon or nitrogen of indole heterocycles allowed the synthesis of the alkaloids aspidospermidine and goniomitine. 2a Using Phthalimido-substituted cyclopropanes together with iron or tin catalysts, a highly diastereoselective and enantiospecific [3+2] annulation reaction with enol ethers and carbonyls gave access to multi-substituted cyclopentyl- and tetrahydrofuryl amines, key structural elements of both DNA and bioactive compounds. 2b-c Recently, a new iron-catalyzed [2+2] cycloaddition reaction between alkylidene malonates and enimides was also developed to access aminocyclobutanes, setting the bases for an analogous [4+2] process. 2d

(1) (a) Nicolai, S.; Piemontesi, C.; Waser, J., Angew. Chem., Int. Ed. 2011, 50, 4680. (b) Nicolai, S.; Waser, J., Org. Lett. 2011, 13, 6324. (c) Nicolai, S.; Sedigh-Zadeh, R.; Waser, J., J. Org. Chem. 2013, 78, 3783. (2) (a) De Simone, F.; Gertsch, J.; Waser, J., Angew. Chem., Int. Ed. 2010, 49, 5767. (b) de Nanteuil, F.; Waser, J., Angew. Chem., Int. Ed. 2011, 50, 12075. (c) Benfatti, F.; de Nanteuil, F.; Waser, J., Org. Lett. 2012, 14, 386. (d) de Nanteuil, F.; Waser, J., Angew. Chem., Int. Ed. 2013, 52, ASAP: DOI: 10.1002/anie.201303803.

Title: Unique Catalytic Activity Exhibited by Transition-metal Silyl Complexes
Speaker:Professor Hiroshi Nakazawa
Date:19 August 2013
Time:2:00pm – 3:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Rei Kinjo
Abstract:

Reactivity of a silyl ligand on a transition metal is quite different from that of an alkyl ligand. We discovered unique catalytic activity of transition metal complexes with a silyl ligand, such as selective bond cleavage of C-CN bond in organonitriles, N-CN bond in cyanamides, OCN bond in cyanates, C=O bond in amides, and C=S bond in thioamides. The details of these reactions and reaction mechanism will be discussed.

Title: Royal Society of Chemistry: supporting the chemical science community
Speaker:Ms Katie Dryden-Holt
Date:19 August 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

The Royal Society of Chemistry is the world’s leading chemistry community. With a member network of 48,000 chemical scientists worldwide, we are a truly global organisation. This talk will introduce the Royal Society of Chemistry and our wide range of activities including our publishing business and conference programme, and will explain the importance of the partnership between the Royal Society of Chemistry and Nanyang Technological University. There will also be an explanation of the support available to chemical scientists through membership of the Royal Society of Chemistry.

Title: Catalytic Rearrangements - Inspiration for Total Synthesis and the Discovery of Unusual Reactivities
Speaker:Dr Nuno Maulide
Date:16 August 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

The turn of the century brought about a pressing need for new, efficient and clean strategies for the chemical synthesis of biologically active compounds.

Our group has studied the use of various molecular rearrangements and atom-economical transformations as particularly appealing means towards the streamlined synthesis of complex small molecule targets.

In this lecture, we will present an overview of our research in these areas and how they may provide efficient solutions for total synthesis as well as platforms for the discovery of unusual reactivity.

Title: Catalytic Enantioselective Carbon-Carbon Bond Formations with Diazoesters
Speaker:Professor Do Hyun Ryu
Date:14 August 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Choon Hong
Abstract:

The chemistry of α-diazocarbonyl compounds has attracted great attention because of its extensive applications in organic chemistry since the first recorded synthesis of ethyl diazoacetate by Curtius in 1883. Recently, we developed highly enantioselective, catalytic cyclopropanation reaction of diazoesters with aldehydes. In the presence of chiral oxazaborolidinium cation as catalyst, cyclopropanation reactions proceeded in high yield (up to 93%) with high to excellent diastereoselectivity (up to 98% de) and enantioselectivity (up to 95% ee).

In addition, catalytic asymmetric Roskamp and C-H insertion reactions of α-alkyl diazoesters with aldehydes proceed with high to excellent enantioselectivities and theses methodologies were applied to synthesis of the natural products, such as sitophilate and (+)- epijuvabione.

[1] (a) L. Gao, G.-S. Hwang, M. Y. Lee, D. H. Ryu Chem Commun. 2009, 5460-5462. (b) B. K. Senapati, G.-S. Hwang, S. Lee, D. H. Ryu Angew. Chem. Int. Ed. 2009, 48, 4398-4401. [2] (a) L. Gao, G.-S. Hwang, D. H. Ryu J. Am. Chem. Soc. 2011, 133, 20708-20711. (b) L. Gao, B. C. Kang, G.-S. Hwang, D. H. Ryu Angew. Chem. Int. Ed. 2012, 51, 8322-8325. [3] (a) S. I. Lee, B. C. Kang, G.-S. Hwang, D. H. Ryu Org. Lett. 2013, 15, 1428 (b) S. I. Lee, G.- S. Hwang, D. H. Ryu J. Am. Chem. Soc. 2013, 135, 7126.

Title: New Horizons in Gold Catalysis
Speaker:Professor Stephen Hashmi
Date:7 August 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Philip Chan
Abstract:

Latest developments in homogeneous gold catalysis will be presented. This will include the design of new catalysts, the development of new reactions, mechanistic investigation of the mechanism of these reactions and computational studies.

Title: Living Radical Polymerization with Organic Catalysts: From Fundamental Reactions to Material Design
Speaker:Professor Atsushi Goto
Date:5 August 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

Controlled radical polymerization, so-called living radical polymerization (LRP), has attracted growing attention as a powerful method for synthesizing well-defined, low-polydispersity polymers. The seminar will introduce a new family of LRP using organic catalysts, which we recently developed. It is the first LRP using non-metal catalysts, and is based on a new mechanism in LRP. The catalysts include inexpensive organic molecules such as amines and phosphines and also even perfectly non-toxic vitamins. This system is applicable to a variety of monomers and polymer structures. Also interestingly, the polymerization can be induced by not only thermal heating but also photo irradiation. This system is now commercially used in industry and is also proposing new materials because of its facile access to a wide range of polymer design. The chemistry of this polymerization and some applications, e.g., application to polymer brush materials and their fascinating properties, will be presented.

Title: Transition Metal-Free Coupling Reactions of Aryl Halides
Speaker:Professor Eiji Shirakawa
Date:29 July 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

Transition metal catalysis is widely utilized in substitution reactions of readily available aryl halides (Ar–X). They are activated through two electron reduction by transition metals (M) to form Ar–M–X, which react with arenes, alkenes and organometals to give substitution products such as biaryls and styrenes. Single electron reduction is also effective for activation of Ar–X. The resulting [Ar–X] • – undergoes decomposition to Ar • , which reacts with sp3 -carbon nucleophiles but not with sp2 -carbon nucleophiles. We found that the single electron transfer induces the coupling reaction of aryl halides with various sp2 -carbon nucleophiles to give biaryls and styrene derivatives with no aid of transition metal catalysis: aryl radicals react with arenes (A) 1 and styrenes (B) 2 with the aid of tertbutoxide, whereas aryl Grignard reagents react with anion radicals [Ar–X] • – before elimination of X – (C). 3–6

(1) Shirakawa, E.; Itoh, K.; Higashino, T.; Hayashi, T. J. Am. Chem. Soc. 2010, 132, 15537. (2) Shirakawa, E.; Zhang, X.; Hayashi, T. Angew. Chem. Int. Ed. 2011, 50, 4671. (3) Shirakawa, E.; Hayashi, Y.; Itoh, K.; Watabe, R.; Uchiyama, N.; Konagaya, W.; Masui, S.; Hayashi, T. Angew. Chem., Int. Ed. 2012, 51, 218. (4) Uchiyama, N.; Shirakawa, E.; Hayashi, T. Chem. Commun. 2013, 49, 364. (5) Shirakawa, E.; Watabe, R.; Murakami, T.; Hayashi, T. Chem. Commun. 2013, 49, 5219. (6) Account: Shirakawa, E.; Hayashi, T. Chem. Lett. 2012, 41, 130.

Title: N-Heterocyclic Carbenes in Catalysis: A Critical Review
Speaker:Professor Wolfgang A. Herrmann
Date:25 July 2013
Time:3:30pm – 4:45pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Francois Mathey
Abstract:

In 1995, the first report on the ability of N-heterocyclic carbenes (NHC) to act as steering ligands was published by our group, showing the potential of this ligand class in homogeneous catalysis. Since then, more than 3,000 publications and patents on NHC have been published. Noteworthy, NHCs are playing a key role in various important catalytic processes, resulting in three Nobel prizes so far (Heck, Suzuki, Grubbs). NHC compounds are extremely versatile ligands: they are easy to modify and functionalize, e.g. for a solubilization of the complexes in water or immobilization on solid supports for a better catalyst-product separation. The control over the electronic and steric properties, as well as the introduction of chiral information is being used to adjust the activity and selectivity of the homogeneous metal catalysts.

The conversion of ubiquitous carbon sources to energy carriers or bulk chemicals is one of the biggest challenges in catalysis today. Usually, these processes require the activation of strong bonds, which demands tailor-made (molecular) catalysts, which exhibit a high selectivity and activity as well as a high tolerance of functional groups. The research group focuses on the design of novel NHC ligands for transition metals (e. g. for catalytic hydrogenations in water, C-H activation reactions of aliphatic and aromatic compounds, enantioselective hydrosilylation, activation of small molecules). Additionally, new synthetic approaches to novel carbenes, which have so far not been accessible are developed. Some of these carbenes allow unprecedented modulations of steric and electronic properties.

Title: Regulated Equilibria and Compartmentalization in Synthetic Chemistry
Speaker:Professor Ognjen Miljanić
Date:25 July 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract:

At present, there is a large disconnect between the ways biological systems and laboratory chemists pursue chemical synthesis. Living organisms simultaneously synthesize multiple sophisticated molecules with absolute chemo-, regio-, and stereoselectivity, starting from highly complex "soups" of chemical precursors found within a cell. In contrast, laboratory synthesis is largely reductionist in its approach: most synthetic transformations combine two high-purity precursors with a high-purity catalyst, often in the absence of air and moisture, to produce a third chemical.

The research performed in the Miljanić research group at the University of Houston aims to bridge this divide. Using equilibrating collections of compounds known as dynamic combinatorial libraries (DCLs), we have shown that complex mixtures of precursors can be used to synthesize multiple pure products in high yields and selectivities. This synthetic strategy is known as kinetic self-sorting and holds the potential to yield cost savings in the basic chemical industry, where multiple value-added chemicals could be produced simultaneously. In addition, our recent work on perfluorinated metal-organic frameworks (MOFs) is the first step towards preparing microenvironments for selective encapsulation and reactivity within crystals of porous materials. Within these pores, another biological principle—namely, physical compartmentalization—could be tested as a synthetic tool, as incompatible chemistries could be isolated within pores of different MOFs, which would act as analogs of cellular organelles.

Taken summarily, these two novel synthetic approaches are being developed to allow more rapid access to new functional molecules and materials of interest in sensing, separations, and energy applications. As just one example, this presentation will highlightthe synthesis and characterization of fluorophores based on benzobisoxazole and benzimidazole nuclei. These "cruciform fluorophores" can be used to qualitatively distinguish among structurally closely related analytes from several important compound classes, including carboxylic and boronic acids, phenols, amines, ureas, and anions.

Title: Hydrazone-Based Switches, Fluorophores, and Sensors
Speaker:Professor Ivan Aprahamian
Date:24 July 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract:

Can structurally simple molecular switches that can be synthesized in a few easy steps, perform complicated functions? This question is imperative to the field of molecular switches and machines because the multistep synthesis used in the current state-of-the-art systems is a bottleneck that impedes fast progress and deployment. To address this problem we have been developing for the past few years,simple, modular and tunable hydrazone-based rotary switches that can be easily incorporated into adaptive materials. The presentation will deal with our recent advances with these switches, and efforts to convert the versatile hydrazone systems into solid-state and/or water soluble fluorophores that can be used in sensing applications.

Representative references: 1. D. Ray, J. T. Foy, R. P. Hughes, I. Aprahamian, Nature Chem. 2012, 4, 757-762. 2. Y. Yang, X. Su, C. Carroll, I. Aprahamian, Chem. Sci. 2012, 3, 610–613. 3. X. Su, M. Liptak, I. Aprahamian, Chem. Commun. 2013, DOI: 10.1039/C2CC34976K.

Title: Catalysis in Pharmaceuticals and Fine Chemicals
Speaker:Dr Nitin Patil
Date:23 July 2013
Time:2:30pm – 3:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract:

In the last decade significant research has been directed towards development of catalysts for synthetic efficiency and atom economy processes. This talk has an overview of the developments in Precious Group Catalysts (Heterogeneous, Homogeneous) & Biocatalysis/enzymes. An outline of New ranges of highly active and selective catalysts which have been developed for various applications like Hydrogenations, Coupling and Chiral asymmetric synthesis applications. Biocatalysis/ Enzymes are an important asset to the catalytic toolbox for the production of fine chemicals and pharmaceuticals. The synthetic scope and catalytic activity of enzymes oftencomplement chemical catalysis. Consequently, oxidoreductases are a valuable tool in organic chemistry for the synthesis of chiral alcohols. Besides high activity and selectivity of the biocatalyst for the application on an industrial scale the availability and robustness of theenzyme under process conditions are of key importance. The presentation also features the chemistries & application of these catalyst products/enzymes in the Fine Chemical and Pharmaceutical Industry.

Title: Carbonylation in Flow
Speaker:Professor Takahide Fukuyama
Date:9 July 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

Microreactors have brought significant impacts on chemical synthesis and production because of their advantageous characteristics over batch reactors, which include highly efficient mixing, efficient heat transfer ability, precise control of the residence time, large surface areato-volume ratio, and high operational safety. Microreactor technology can contribute even for gas-liquid biphasic reactions, for which large interfacial area between two phases is a key to the success. I will introduce our recent results on carbonylation reactions using a flow micro reactor.

Title: Nanostructured materials and their functional applications
Speaker:Professor Qiang Xu
Date:5 July 2013
Time:3:00pm – 4:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract:

This presentation includes following two topics:

1) Porous metal-organic frameworks (MOFs) as platforms for functional applications

There has been a rapid development in metal-organic frameworks (MOFs), especially porous MOFs, due to their high potential for diverse applications in the past decade. Recently, we have successfully synthesized a number of new porous MOFs and found their new applications as catalysts, as templates for nanoporous carbon synthesis, and as supports for metal nanoparticles as well as for large molecule separation. Novel porous metal-organic frameworks have been synthesized, which presents a stable catalytic activity for the oxidation of CO to CO2 . Porous carbon has been synthesized by using MOF-5 or ZIF-8 as a template and the resultant carbon displayed a high specific surface area and hydrogen uptake as well as excellent electrochemical properties as an electrode material for electric double-layered capacitor (EDLC). Metal nanoparticles (NPs) have been deposited to MOFs, which exhibit excellent catalytic performances in various reactions. Mesoporous MOFs have been successfully synthesized, which can be used for separating large dye molecules. Crystalline MOF nanosheets have been fabricated via top-down delamination from bulk crystals of a layered MOF, which exhibit remarkable amine intercalation property and reversible amine exchangeability.

2) Metal nanoparticle-catalyzed hydrogen generation from liquid-phase chemical hydrogen storage materials

Hydrogen, H2 , is a globally accepted clean fuel. The use of hydrogen fuel cells in vehicles or in portable electronic devices requires lightweight H2 storage or “on-board” hydrogen generation, for which the most important are safety, ease to control and fast kinetics of the hydrogen release along with a high hydrogen content. Here we report excellent liquid-phase hydrogen generation systems suitable for use as portable hydrogen sources, which are based on metal nanoparticle-catalyzed hydrolysis of ammonia borane (NH3BH3 ), complete decomposition of hydrous hydrazine (H2NNH2 ) and decomposition of formic acid. NH3BH3 dissolves in water to form a stable solution, to which the addition of a catalytic amount of suitable metal catalysts leads to rigorous release of hydrogen gas with an H2 to NH3BH3 ratio up to 3.0. Metal and metal-alloy nanoparticles (NPs) effectively catalyze the decomposition of hydrous hydrazine to selectively produce hydrogen under ambient reaction conditions. Gold-palladium alloy nanoparticles immobilized to mesoporous MOFs and monometallic gold nanoparticles encapsulated in amine-functionalized silica nanopheres exhibit high performances for catalytic decomposition of formic acid to H2 and CO2 , the latter showing strong metal-molecular support interaction (SMMSI), an unusual effect from the molecular functionalization of metal/support. In addition, we have developed a novel direct ammonia borane fuel cell (DABFC) by combining the anodic oxidation of ammonia borane (Hto H+ ) and the cathodic reduction of O2 .

Title: Design, Synthesis and Biological Application of in Vivo Imaging Probes with Tunable Chemical Switches
Speaker:Professor Kazuya Kikuchi
Date:4 July 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Xing Bengang
Abstract:

One of the great challenges in the post-genome era is to clarify the biological significance of intracellular molecules directly in living cells. If we can visualize a molecule in action, it is possible to acquire biological information, which is unavailable if we deal with cell homogenates. One possible approach is to design and synthesize chemical probes that can convert biological information to chemical output. Fluorescence protein labeling by synthetic probes is a powerful approach to investigate protein function and localization inside living cells. This chemistry-based technique utilizes a pair of a protein tag and its specific ligands connected to fluorophores. Its potential advantage is that various fluorescent molecules are available as labeling reagents, and the timing of protein labeling is easily controlled. Because of these characteristics, this method is attracting attention as an alternative of fluorescent proteins. On the other hand, in this labeling system, there is a problem that the fluorescence of free probes inside cells prevents the identification of labeled proteins. Thus, washing procedures are required to remove the free probes from cells. However, if the probes are not completely washed out, the remaining probes cause the reduction of the signal-to-noise ratio. As a solution of this problem, we previously developed a fluorogenic probe for labeling photoactive yellow protein (PYP) tag. PYP is a small protein (14 kDa) derived from purple bacteria, and binds to the thioester derivatives of cinnamic acid/coumarin through transthioesterification with Cys69. Novel fluorogenic probes, which possess 4-hydroxycinnamic acid or 7- dimethylaminocoumarin as a ligand scaffold, were synthesized. The labeling kinetics wassignificantly improved by these probes. Furthermore, no-wash labeling of intracellular proteins wassuccessfully achieved. Magnetic resonance imaging (MRI) is an imaging modality adequate for in vivo studies. Therefore, many scientists are interested in the development of MRI probes capable of detecting enzyme activities in vivo. Because background signal is hardly detectable, 19F-MRI probes are promising for in vivo imaging. A novel design strategy for 19F-MRI probes to detect protease activities is proposed. The design principle is based on the paramagnetic relaxation effect from Gd3+ to 19F. A peptide was synthesized, Gd-DOTA-DEVD-Tfb, attached to a Gd3+ complex at the N-terminus and a 19F-containing group at the C-terminus. The 19F-NMR transverse relaxation time (T2 ) of the compound was largely shortened by the paramagnetic effect of intramolecular Gd3+. The peptide was designed to have a sequence cleaved by an apoptotic protease, caspase-3. When the peptide wasincubated with caspase-3, the peptide was cleaved and subsequently the Gd3+ complex and the 19F-containing group were separated from each other. T2, after cleavage, was extended to cancel the intramolecular paramagnetic interaction. T2 is a parameter that can be used to generate contrastsin MR images. Using this probe as a positive contrast agent, the probe could detect caspase-3 activity spatially from an image using 19F MRI.
Title: Enabling Organophosphorus Chemistry
Speaker:Professor Koop Lammertsma
Date:3 July 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Francois Mathey
Abstract:

Organophosphorus ligands are ubiquitous in catalysis with a still expanding diversity in viable applications that are centered mostly on the higher valency of phosphorus. Yet, transition metal complexes containing low-valent phosphorus groups are rapidly coming to the fore with their applicability depending on accessibility. We have developed convenient strategies toward such systems, but also pursue systems devoid of transition metals such as frustrated Lewis pairs.

Exemplary are the phosphinidenes, the P-analogues of carbenes, whose remarkable reactivity, observable only by fast spectroscopy, can be tempered by coordination to a transition metal group into Fischer-type and Schrock-type complexes. The reactivity of the electrophilic ones underscores the analogy with hydrocarbon chemistry, showing that an array of strained molecular systems can be synthesized with remarkable ease. Inherently different are the nucleophilic complexes. These are accessible by simple synthetic routes and show great potential in catalytic systems. The need for highly efficient synthetic methodologies toward complex organophosphorus systems is essential for further development of this chemistry.

Novel avenues for phosphaalkynes will be presented that involve the reaction with metalates as a prelude to sandwiches, cyclization, and tackling white phosphorus, emphasizing redox chemistry. The combined use phosphorus and alkynes presents new opportunities, ranging from cage compounds and/or catalysts to exceptional FLPs. The joint action of P and Al and/or B provides tremendous opportunities for developing highly active catalytic systems. Openings will be presented that illustrate their activity to H2 , CO2 , RNCO, and (de)hydrogenation.

Whereas mono- and bidentate phosphorus ligands are ubiquitous in catalysis, those with P- and N-sites are rare because of their limited accessibility. Routes will be presented based on reactive intermediates, thereby providing new opportunities in catalysis.

Finally, insight will be given on stereomutations in pentacoordinate systems. These are relevant for P- and Si-compounds and for many transition metal complexes.

Title: Porphysome Nanotechnology: Explore New Frontiers of Cancer Imaging and Therapy
Speaker:Professor Zheng Gang
Date:2 July 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Xing Bengang
Abstract:Porphyrins are the endogenous chromophores of nature such as hemes in red blood cells and chlorophylls in green plants. Porphyrins and porphyrin-like molecules are well known photosensitizers for photodynamic therapy and fluorescence imaging, and there has been rekindled interest for nuclear medicine given their radioisotope chelating ability. In the course of examining porphyrin self-quenching in liposomes to explore their potential use as activatable photosensitizers, we discovered ‘porphysomes’, the first all-organic nanoparticles with intrinsic multimodal photonic properties. They are self-assembled from porphyrin-lipid building blocks to form liposome-like bilayer vesicle (~100 nm diameter). The very high porphyrin packing density (>80,000 per particle) results in both ‘super’-absorption and structure-dependent ‘super’- quenching, which, in turn, converts light energy to heat with extremely high efficiency, giving them ideal photothermal and photoacoustic properties that are unprecedented for organic nanoparticles. Upon porphysome nanostructure dissociation, fluorescence of free porphyrins is restored to enable low background fluorescence imaging. In addition, metal ions (e.g., radioactive copper-64) can be directly incorporated into the porphyrin building blocks of the preformed porphysomes thus unlocking their potential for PET, MRI and radiation therapy. As a result of their organic nature, porphysomes were biodegradable in vivo and induced minimal acute toxicity in mice with high intravenous doses. In a similar manner to liposomes, porphysomes can be easily scaled up via commercial extrusion techniques and the large aqueous core of porphysomes could be passively or actively loaded with drugs, opening up a new avenue for image-guided drug delivery. By changing the way porphyrin-lipid assembles, we developed ultra small porphyrin nanodiscs (<20nm) and large porphyrin shell microbubbles (~2um), expanding the purview of porphyrin nanophotonics. Compared with classical “all-in-one” nanoparticles containing many functional modules, the simple yet “one-for-all” nature of porphysomes represents a novel approach to the design of multifunctional nanoparticle and confers high potential for clinical translation.
Title: Protein Folding – possible extension to Membrane Bound Proteins
Speaker:Professor Pernilla Wittung-Stafshede
Date:28 June 2013
Time:3:15pm–4:15pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Xing Bengang
Title: Coherent Ultrafast Multidimensional Spectroscopy of Molecules; From NMR to X Rays
Speaker:Professor Shaul Mukamel
Date:28 June 2013
Time:1:45pm – 3:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Tan Howe Siang
Abstract:

Time-domain experiments that employ sequences of optical pulses in order to probe electronic and nuclear dynamics in molecules are made possible by newly developed lasers ranging from the infrared to the soft and hard x-rays. Recent progress in these multidimensional techniques which originated in NMR may be used to probe elementary molecular events which will be surveyed. Energy-transfer and charge-separation pathways in chromophore aggregates and in the bacterial photosynthetic reaction centers may be revealed by coherent two-dimensional optical spectroscopy. The excited state dynamics and relaxation of electrons and holes are closely monitored. New free-electron laser and high-harmonic generation x-ray light sources are capable of supplying pulses short and intense enough to perform resonant nonlinear time-resolved experiments in molecules. Valence electron motions can be triggered impulsively by core excitations and monitored with high temporal and spatial resolution. Sequences of attosecond x-ray pulses can probe quantum coherence and correlations of valence electrons, building upon the analogy with existing studies of vibrational motions using femtosecond techniques in the visible regime. By creating multiple core holes at controlled times it is possible to study the dynamics and correlations of valence electrons as they respond to these perturbations. Applications will be presented to the stimulated x-ray Raman spectra of trans-N-methylacetamide and Cysteine at the Nitrogen, Sulfur and the Oxygen K-edges and to electron-hole motions in porphyrin aggregates. The signals are interpreted in terms of the dynamics of valence electronic wave packets prepared and detected in the vicinity of a selected atom.

"Resolving the Electron Transfer Kinetics in the Bacterial Reaction Center by Pulse Polarized 2-D Photon Echo Spectroscopy", B.P. Fingerhut, and S. Mukamel. J.Phys.Chem. Lett, 3, 1798-1805 (2012) J. Biggs, D. Healion, Y. Zhang, and S. Mukamel. "Multidimensional Attosecond Resonant X-ray Spectroscopy of Molecules; Lessons from the Optical Regime", Ann Rev Phys Chem , 64, 101-127 (2013) "Monitoring Non-adiabatic Dynamics of the RNA Base Uracil by UV-Pump-IR-Probe Spectroscopy", B.P. Fingerhut, K.E. Dorfman, and S. Mukamel. J. Phys. Chem. Lett (2013)

Title: Asymmetric Synthesis of C3 Symmetric Buckybowls
Speaker:Professor Hidehiro Sakurai
Date:27 June 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Title: Colloids with directional interactions
Speaker:Professor David Pine
Date:14 June 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Ling Xing Yi
Abstract:

We have developed new kinds of colloidal particles with either geometrical or chemical patches that give rise to directional interactions. These interactions allow colloids to interact with each other more like atoms, which in turn are used to build up structures that are not possible with isotropic interactions. These directional interactions are being developed to make self-replicating colloidal motifs and new colloidal crystals.

References: Nature 491, 51–55 (2012), Nature 464, 575-578 (2010).

Title: Applications of Nanomaterials and Magnetic nanomaterials in Organic Synthesis – A new generation catalysts
Speaker:Dr Manoj Gawande
Date:13 June 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Choon Hong
Abstract:

The environmentally friendly methodologies have been the driving force of organic chemists and scientists in recent years. Attractive and innovative protocols that nowadays are even part of industrial ventures including nanomaterials, magnetic nanomaterials and friendly reaction condition’s such as use of Microwave irradiation technique, aqueous media, and or solvent-free reaction media. These topics have extensively covered the preparation and design of (nano)materials and their utilization in heterogeneously catalyzed reactions in organic synthesis. In this talk, we aim to provide an overview of recent trends from our group in the utilization of novel methodologies on nanomaterial’s, magnetic nanomaterial’s, (supported metal and metal oxide nanoparticles and related nanostructures), and their applications in (oxidations, hydrogenations, and multicomponent reactions) and other some important organic reactions.

Selected Publications- M.B. Gawande et al, Chem. Soc. Rev., 2013, 42, 3371-3393; Green Chem.2013, 15, 682-689. Chemistry – A Eur. J. 2012, 18, 12628; Bioorg. Med. Chem. Lett. 2012, 22, 5727–5730. Chem. Soc. Rev., 2013, 42, 5522-5551 ; Green Chem., 2013, 15, 1226-1231

Title: The diastereoselective synthesis of a-fluoro- and a,a-difluoro-b-amino acids, and w-conotoxin GVIA mimetics
Speaker:Dr Peter Duggan
Date:23 May 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Choon Hong
Abstract:

In this seminar, synthetic approaches to fluorinated b-amino acids will be described. For mono-fluorinated compounds, this has involved a diastereoselective conjugate addition/electrophilic fluorination strategy, whereas the difluorinated compounds were prepared using a diastereoslective sonocatalysed Reformatsky addition as a key step.

The second part of the seminar will cover the evolution of mimics of omega-conotoxin GVIA into small molecules that selectively block the neuronal calcium ion channel Cav2.2, known to be important in pain transmission.

Title: The diastereoselective synthesis of a-fluoro- and a,a-difluoro-b-amino acids, and w-conotoxin GVIA mimetics
Speaker:Dr Peter Duggan
Date:23 May 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Choon Hong
Abstract:

In this seminar, synthetic approaches to fluorinated b-amino acids will be described. For mono-fluorinated compounds, this has involved a diastereoselective conjugate addition/electrophilic fluorination strategy, whereas the difluorinated compounds were prepared using a diastereoslective sonocatalysed Reformatsky addition as a key step.

The second part of the seminar will cover the evolution of mimics of omega-conotoxin GVIA into small molecules that selectively block the neuronal calcium ion channel Cav2.2, known to be important in pain transmission.

Title: Recent Adventures in Heterocyclic Chemistry: Novel Lewis Acid Mediated Reactions and Alkaloid Targeted Synthesis
Speaker:Professor Stephen Pyne
Date:16 May 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract:This talk will highlight our recent progress on exploiting the dual reactivity of α,β-unsaturated-N-acyliminium ions for the synthesis of novel spirocyclic and bridged heterocyclic structures (e. g. 1 and 2 ) and progress towards the synthesis of broussonetines I, J, J1 and J2 (3).
Title: Aromatic Architectures
Speaker:Professor Jay Siegel
Date:2 May 2013
Time:11:00am–12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba 
Title: beta-Peptidic Peptidomimetics
Speaker:Professor Dr Dieter Seebach
Date:26 April 2013
Time:11:00am–12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Steve Zhou
Title: Syntheses and Structures of beta-Peptides
Speaker:Professor Dr Dieter Seebach
Date:25 April 2013
Time:11:00am–12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Steve Zhou
Title: Fluorescent Nucleic Acid Systems: Design and Construction
Speaker:Professor Byeang Hyean Kim
Date:22 April 2013 
Time:10:00am – 11:30am
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Phan Anh Tuan
Abstract:

Fluorescent nucleic acid systems are widely applied in various fields, from fundamental biological probes to nano-construction. [1] Nucleic acids are used as a scaffold for arranging aromatic fluorophore assemblies, either by insertion into the DNA base pairs or by stacking via the duplex. Moreover, chemical modifications of nucleic acids are accessible by the modified DNA phosphoramidites or postsynthetic approach, and provide with new and interesting fluorescent nucleic acids systems. Fluorescent nucleic acid systems represent an extensive and exciting research area in chemistry as well as in biotechnology and photophysics. We synthesized and investigated new fluorescent nucleic acid systems for probing single nucleotide polymorphisms (SNPs),[2] structural changes of DNA, [3] ligand interaction with RNA bulge, and applying various optical devices.

We have developed the new type of molecular beacon, quencher-free molecular beacon (QF-MB), that exhibits several advantageous features, including a high level discrimination between the target and its single-mismatched congeners and an economical device set-up due to the absence of the quencher. We have also designed and synthesized the probing system for quadruplex structures of DNA, G-quadruplex and i-motif, and B-Z transition. Strong π–π stacking interactions in nucleic acids can be used to generate novel secondary structures. We investigated the fluorescent phenomena and structures of pyrene modified oligodeoxyadenylate and oligodeoxyguanylate. The covalently linked pyrenes induced the formation of a self-assembled olgiodeoxyadenylate duplex [4] and divergent structures of oligodeoxyguanylate with unique fluorescence phenomena. [5]

References: [1] N. Venkatesan, Y. J. Seo, B. H. Kim, Chem. Soc. Rev. 37 (2008) 648. [2] G. T. Hwang, Y. J. Seo, B. H. Kim, J. Am. Chem. Soc. 126 (2004) 6528. [3] I. J. Lee, J. W. Yi, B. H. Kim, Chem. Commun. (2009) 5383. [4] Y. J. Seo, H. Rhee, T. Joo, B. H. Kim, J. Am. Chem. Soc. 129 (2007) 5244. [5] I. J. Lee, B. H. Kim, Chem. Commun. 48 (2012) 2074, H. S. Jeong, S. M. Choi, H. W. Kim, J. W. Park, H. N. Park, S. M. Park, S. K. Jang, Y. M. Rhee and B. H. Kim, Mol BioSyst. 9 (2013) 948, K. T. Kim and B. H. Kim, Chem. Commun. 49 (2013) 1717.

Title: Nanomaterials for Biomedical and Green Chemistry Applications
Speaker:Professor Jackie Ying
Date:17 April 2013 
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Chen Hongyu
Abstract:

Nanocrystalline materials are of interest for a variety of applications. This talk describes the design and functionalization of nanocomposite materials for biological and chemical applications. Specifically, we have synthesized metallic, metal oxide and semiconducting nanocrystals for bioimaging, bioseparation, biosensing, theranostic, fuel cell and catalytic applications. These nanocrystals are ≤ 10 nm in size and are surface modified to provide for high dispersion, biocompatibility, and water solubility. They are used as building blocks to create multifunctional nanocomposite particles with unique properties.

Nanoporous materials have also been developed with high surface area and high density of functional groups. These systems are employed as novel heterogenized catalysts with excellent activity and recyclability. They are also useful as adsorbents for green chemistry applications.

Title: Cyclic Enaminones -Methodology Development, Alkaloid Synthesis, and Library Construction
Speaker:Dr Hajime Seki
Date:8 April 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Rei Kinjo
Abstract:

Monocyclic and bicyclic enaminones, also known as vinylogous amides, can serve as versatile intermediates due to their reactivity and stability in the synthesis of alkaloids, such as piperidines, indolizidines, and quinolizidines, which often display important biological properties. The demonstration of enaminone chemistry in the synthesis of an indolizidine and the construction of anti-cancer agent library as well as the novel methodologies to synthesize enaminones will be the topics in the seminar.

Title: Probing AI-2 Quorum Sensing Using Structurally Locked Synthetic Modulators
Speaker:Dr Kyoji Tsuchikama
Date:8 April 2013
Time:10:30am – 11:30am
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Rei Kinjo
Abstract:

Bacteria have developed a unique system that coordinates their behavior in a cell population-dependent manner, a process termed quorum sensing. Recent reports have revealed that many pathogenic bacteria regulate their virulence factor production through this mechanism.1,2 In particular, autoinducer-2 (AI-2), a class of signaling molecules in quorum sensing, is known to be utilized by many bacterial species. Therefore, the modulation of the AI-2 system is recognized as a new, potential strategy for combating microbial infection.3 However, it is still challenging to obtain detailed information of the molecular mechanism of this system, which mainly comes from multiplexed equilibrium and tautomerism of AI-2. To obtain greater insight into AI-2 quorum sensing, we designed and synthesized a panel of analogues of the signaling molecule based on structure locking strategies: carbocyclic analogues4 and hydroxyl group-capped analogues.5 In this talk, the speaker will show details of the design strategies, findings and insights into biological consequences obtained with these analogues, and current efforts for further understanding the AI-2 system.

(1) Engebrecht, J.; Nealson, K.; Silverman, M. Cell 1983, 32, 773−781. (2) Fuqua, W. C.; Winans, S. C.; Greenberg, E. P. J. Bacteriol. 1994, 176, 269−275. (3) Waters, C. M.; Bassler, B. L. Annu. Rev. Cell. Dev. Biol. 2005, 21, 319−346. (4) Tsuchikama, K.; Lowery, C. A.; Janda, K. D. J. Org. Chem. 2011, 76, 6981−6989. (5) Tsuchikama, K.; Zhu, J.; Lowery, C. A.; Kaufmann, G. F.; Janda, K. D. J. Am. Chem. Soc. 2012, 134, 13562-13564.

Title: Cyclic Enaminones -Methodology Development, Alkaloid Synthesis, and Library Construction
Speaker:Dr Hajime Seki
Date:8 April 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Rei Kinjo
Abstract:

Monocyclic and bicyclic enaminones, also known as vinylogous amides, can serve as versatile intermediates due to their reactivity and stability in the synthesis of alkaloids, such as piperidines, indolizidines, and quinolizidines, which often display important biological properties. The demonstration of enaminone chemistry in the synthesis of an indolizidine and the construction of anti-cancer agent library as well as the novel methodologies to synthesize enaminones will be the topics in the seminar.

Title: Cyclic Enaminones -Methodology Development, Alkaloid Synthesis, and Library Construction
Speaker:Dr Hajime Seki
Date:8 April 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Rei Kinjo
Abstract:

Monocyclic and bicyclic enaminones, also known as vinylogous amides, can serve as versatile intermediates due to their reactivity and stability in the synthesis of alkaloids, such as piperidines, indolizidines, and quinolizidines, which often display important biological properties. The demonstration of enaminone chemistry in the synthesis of an indolizidine and the construction of anti-cancer agent library as well as the novel methodologies to synthesize enaminones will be the topics in the seminar.

Title: Harnessing the Potential of Helicenes
Speaker:Professor Matthew Fuchter
Date:3 April 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Tan Choon Hong
Abstract:

The ortho-fused aromatic compounds, termed the helicenes, are fascinating molecules whose aromatic framework is rendered helical or spirally coiled due to the inability for conjoined rings to occupy the same plane. As such, the helicenes are one of the few classes of fully conjugated aromatic molecules that display a non-planar, chiral, topology. Carbo- and heterohelicenes have undergone a surge in interest recently due to their unique optical and electronic properties, closely associated with their inherent chirality. 1 Our interest in helicenes lies in: 1) Efficient, robust and scalable methods to synthetically assemble these fascinating molecules, 2 particular in asymmetrically pure form; 2) The use of our target helicenes in diverse multidisciplinary applications. 3-5 This talk will give an overview of our recent results in this area, including our approaches to efficiently prepare helicenes, and how these can be converted into asymmetric synthetic strategies. In particular, metal catalysed cross-coupling, cycloisomerisation chemistry and chiral relay protocols will be discussed. Furthermore, our preliminary study of helicenes in materials science will be disclosed, particularly in the production of novel organic electronic devices. For example, we have recently found that by simply doping a conventional light emitting polymer (F8BT) with a small amount of a single handedness azahelicene, we are able to fabricate circular polarised (CP) light emitting organic light emitting diodes (OLEDs), which emit substantial levels of CP-electroluminescence directly. 4 Furthermore, we have recently found that organic field effect transistors (OFETs) based on enantiomerically pure 1-aza[6]helicene can be fabricated and importantly can reversibly detect CP-light. 5

1. “Helicenes: Synthesis and Applications” Shen, Y. & Chen, C. F. Chem. Rev. 112, 1463. doi: 10.1021/cr200087r 2. Weimar, M.; Fuchter, M. J. Org. Biomol. Chem. 2013, 11, 31. doi: 10.1039/c2ob26806j; “A Scalable and Expedient Route to 1-za[6]helicene Derivatives and its Application to a Chiral-Relay Asymmetric Strategy” Weimar, M.; Correa da Costa, R.; Fuchter, M. J. Submitted 2013. 3. Fuchter, M. J.*; Schaefer, J.; Judge, D. K.; Wardzinski, B.; Weimar, M.; Krossing, I. Dalton Trans. 2012, 41, 8328. doi: 10.1039/c2dt30900a; Fuchter, M. J.*; Weimar, M.; Yang, X.; Judge, D. K.; White, A. J. P. Tetrahedron Lett. 2012, 53,1108. doi:10.1016/j.tetlet.2011.12.082 4. “Induction of Circularly Polarized Electroluminescence from an Achiral Light Emitting Polymer via a Chiral Small Molecule Dopant.” Yang, Y.; Correa da Costa, R.; Smilgies, D. –M.; Campbell, A. J.*; Fuchter, M. J.* Adv. Mater. 2013, accepted. 5. “Chiral light detection via a chiral organic semiconductor transistor” Yang, Y.; Correa da Costa, R.; Fuchter, M. J.*; Campbell, A. J.* Nat. Photon. 2013, accepted.

Title: Insights into photoprotection and photoactivation mechanisms using femtosecond spectroscopy
Speaker:Professor Vasilios Stavros
Date:20 March 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Loh Zhi Heng
Abstract:

Through evolution, molecular function has been finely tuned such that even the most complex of chemical processes occurring in humans takes place with exceptional efficiency. One example relates to the origins of resistance to photochemical damage, or photoprotection, following absorption of UV radiation of DNA bases, amino acids and their subunits. However, even when photochemical damage occurs, the use of transition metal anti-cancer complexes activated through absorption of UV radiation, termed photoactivation, can be used to destroy cancer cells. This talk will discuss our work into the underlying mechanisms of photoprotection in biomolecules and more recently our endeavours into photoactivation mechanisms in transition metal complexes.

Title: Synthesis directed at the disruption of a protein-protein interaction in asthma
Speaker:Professor Alan Spivey
Date:19 March 2013
Time:3:00pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associator Professor Roderick Bates 
Abstract:

Incidence of asthma and related allergic manifestations is increasing in the Western world.1 The symptoms associated with these conditions are invariably debilitating the development of improved therapeutic strategies to combat these afflictions is a healthcare priority. One strategy that offers the prospect of a preventative rather than ameliorative intervention is to administer molecules that can block the interaction of human Immunolobulin E (IgE) with its high affinity receptor FceRI; a protein-protein interaction (PPI) that is central to the allergic signal transduction cascade.2 Proof of principle that this strategy can be effective, and does not suffer from unacceptable side-effects, comes from the successful clinical use of the monoclonal antibody Omalizumab (Xolair® ) which is indicated for severe persistent asthma and operates by sequestering IgE in the blood and preventing binding to FceRI. However, its high cost and non-oral mode of delivery has fuelled interest in the development of alternative antagonists of this PPI.3 We have been investigating approaches to disrupting this PPI based on both tolan-constrained peptides based on a hot spot epitope of IgE4,5 and based on a natural product antagonist, aspercyclide A.6

References: 1. Eder, W.; Ege, M. J.; von Mutius, E. New Engl. J. Med. 2006, 355, 2226-2235. 2. Gould, H. J.; Sutton, B. J. Nature Rev. Immunol. 2008, 8, 205-217. 3. Holgate, S.; Casale, T.; Wenzel, S.; Bousquet, J.; Deniz, Y.; Reisner, C. J. Allergy Clin. Immunol. 2005, 115, 459-465. 4. Spivey, A. C.; McKendrick, J.; Srikaran, R.; Helm, B. A. J. Org. Chem. 2003, 68, 1843-1851 5. Offermann, D.A.; McKendrick, J.E.; Sejberg, J.J.P.; Mo, B.; Holdom, M.D.; Helm, B.A.; Leatherbarrow, R.J.; Beavil, A.J.; Sutton, B.J.; Spivey, A.C., J. Org. Chem. 2012, 77, 3197-3214. 6. Carr, J. L.; Sejberg, J. J. P.; Saab, F.; Holdom, M. D.; Davies, A. M.; White, A. J. P.; Leatherbarrow, R. J.; Beavil, A. J.; Sutton, B. J.; Lindell, S. D.; Spivey, A. C. Org. Biomol. Chem. 2011, 6814-6824.

Title: Chromogenic and Ditopic Fluorescent Sensing of Heavy Metal Ions Based on Functionalized Calix[4]arenes
Speaker:Professor Wen-Sheng Chung
Date:18 March 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associator Professor Shunsuke Chiba 
Abstract:

In the past few years, we have been interested in the design and synthesis of chromogenic and fluorogenic sensors for metal ions and anions. [1,2] Our methodology is to attach isoxazoline, isoxazole, or triazole units onto the upper or lower rims of calix[4]arenes by 1,3- dipolar cycloaddition reactions, [2] followed by ring opening reactions of the corresponding heterocycles provided arrays of bifunctional groups that are found to be useful in metal ions sensing. [2,3] For example, a triazole-modified calix[4]crown in 1,3-alternate conformation can behave as a Pb2+ /K+ off-on switchable fluorescent chemosensor. [2a] Moreover, a ditopic fluorescent chemosensor L for the selective binding of one or two equivalents of Ag+ ions with opposite fluorescence responses was accomplished by the judicious design and synthesis of ligands on both sides of the 1,3-alternate calix[4]arene skeleton using click chemistry, 1,3-dipolar cycloaddition, and subsequent ring-opening procedures. [3] If time is allowed, I shall also report our recent progress in the design and synthesis of intrinsically chiral biscalix[4]arenes. [3b]

Reference: [1]. (a) Ho, I.-T.; Lee, G.-H.; Chung, W.-S. J. Org. Chem. 2007, 74, 2434. (b) Chen, Y.-J.; Chung, W.-S. Eur. J. Org. Chem. 2009, 4470. [2]. (a) Chang, K.-C.; Su, I.-H.; Senthilvelan, A.; Chung, W.-S. Org. Lett., 2007, 9, 3363; (b) Senthilvelan, A.; Ho, I.-T.; Chang, K.-C.; Lee, G.-H.; Liu, I.-H.; Chung, W.-S. Chem. Eur. J. 2009, 15, 6152. [3]. (a) Ho, I.-T; Huang, K.-C.; Chung, W.-S. Chem.-Asian J. 2011, 6, 2738; (b) Luo, J.; Shen, L.-C.; Chung, W.-S. J. Org. Chem. 2010, 74, 464. (b) Tsai, C.-C.; Ho, I.-T.; Chu, J.-H.; Shen, L.-C.; Huang, S.-L.; Chung, W.-S. J. Org. Chem. 2012, 77, 2254.

Title: New Developments in Chiral Phosphate Based Asymmetric Methodology
Speaker:Professor Jon Antilla
Date:15 March 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Robin Chi 
Abstract:

Organocatalysis is considered by many to be an attractive, and potential “green” alternative to traditional metal-based catalysis. This research specifically seeks to develop new reaction methodologies that utilize chiral phosphoric acids as functional asymmetric organocatalysts for synthetically useful transformations. A second major direction is to utilize chiral phosphates as ligands for metal catalysis. In this presentation several new reaction methodologies that utilize chiral phosphoric acids or chiral phosphate metal complexes will be described and discussed. Our initial discoveries and our most recent developments that allow for the asymmetric allylation and propargylation of aldehydes will be highlighted. In addition new Diels-Alder and Hetero-Diels-Alder developments will also be introduced. Mechanistic efforts will be discussed, and will focus on computational analysis and NMR experiments.

Title: A Biomimetic Approach Towards General and Selective Catalysis
Speaker:Professor Li Deng
Date:7 March 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba 
Abstract:

 

Organic molecule-mediated selective catalysis (i.e. selective organocatalysis) has evolved into a generally applicable, powerful strategy for asymmetric synthesis over the last decade. The advent of selective organocatalysis is marked by the discovery and development of a variety of fundamentally important modes of catalysis, which include general acid catalysis by chiral thioureas, general base catalysis by cinchona alkaloids, iminium as well as enamine catalysis by prolines and synthetic chiral amines, phase transfer catalysis, nucleophilic catalysis and NHC catalysis. During the last several years, the introduction and development of biomimetic concepts such as cooperative catalysis and multifunctional catalysis have played a transformative role in expanding the generality and increasing the complexity of selective organocatalysis. This lecture focuses on key advances made and lessons learned from synthetic and mechanistic studies of bioimetic enantioselective catalysis with organic molecules.

 

Title: Chirality-Switchable Polymer-based Ligands for Catalytic Asymmetric Synthesis
Speaker:Professor Michinori Suginome
Date:5 March 2013 
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract:

Considerable effort is being made to establish "next-generation" chiral catalysts for asymmetric organic synthesis. Such catalysts are expected to realize new, innovative catalytic reactions, and to afford not only high enantioselectivity, but also high catalytic activity, better recoverability, and reusability. Through these characteristics, the next-generation chiral catalysts shall unequivocally contribute to the development of "green processes" in asymmetric synthesis. It is also expected for such new chiral catalysts to possess "a switch" by which the chirality of the catalyst can be interconverted. This feature allows synthetic organic chemist to escape from preparation of two enantiomeric catalysts for stereoselective production of both enantiomers. In this presentation are discussed new poly(quinoxaline-2,3- diyl)-based chiral ligands PQXphos (R)-L1, which show high enantioselectivities (>95% ee for three different reactions), high reusability (up to 8-time reuse), and higher catalyst activity than do the corresponding low-molecular-weight chiral ligands. In addition, the polymer backbone underwent perfect switch of helical chirality by the effect of solvent. This feature could be successfully applied to new catalytic systems in which either enantiomer can be produced with high enantioselectivities from a single chiral ligand, whose helical chirality is easily switchable. Palladium-catalyzed asymmetric reactions including asymmetric hydrosilylation of styrenes,1,2 asymmetric biaryl synthesis via Suzuki–Miyaura coupling,3 and C–C bond cleaving desymmetrization of meso-methylenecyclopropanes4 shall be discussed.5

References 1 T. Yamamoto, M. Suginome, Angew. Chem., Int. Ed. 2009, 48, 539. 2 T. Yamamoto, T. Yamada, Y. Nagata, M. Suginome, J. Am. Chem. Soc., 2010, 132, 7899. 3 T. Yamamoto, Y. Akai, Y. Nagata, M. Suginome, Angew. Chem., Int. Ed. 2011, 50, 8844. 4 Y. Akai, T. Yamamoto, Y. Nagata, T. Ohmura, M. Suginome, J. Am. Chem. Soc., 2012, 134, 11092. 5 M. Suginome, T. Yamamoto, Y. Nagata, T. Yamada, Y. Akai, Pure Appl. Chem. 2012, 84, 1759.

Title: Why Does Nature Use High Spin Enzymes for Bond Activation?
Speaker:Professor Sason Shaik
Date:27 February 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract:

To answer the title question, my talk will discuss exchange-enhanced reactivity (EER),1 which is the Hund’s rule analogue in chemical reactivity. The wide-ranging utility of the concept will be outlined. [1] Shaik, S., Chen, H., Janardanan, D. Nature Chem. 3 (2011) 19-27. (b) Chen, H., Lai, W.Z., Shaik, S., J. Phys. Chem. Lett. 1 (2010), 1533-1540. (c) Dandamudi, U.; Janardanan, D.; Li, C.; Shaik, S. Acc. Chem. Res. (2013)

Title: Neutral Network Applications in Potential Energy Surface Construction and Density Functional Theory Calculations for Metal-Graphene and Metal-Silicene Interactions
Speaker:Dr Hung M. Le
Date:26 February 2013
Time:3:00pm – 4:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract:

Artificial neural network (NN) is a powerful and robust tool in machine learning algorithm. In theoretical reaction dynamics, this tool has been vastly employed to fit potential energy surfaces of small molecules/molecular systems. Typically, different case studies can be listed, including the dissociation reactions of HONO, HOOH, O3 , ClOOCl, as well as the exchange reaction of BeH+H2 . NN has been shown to have a great potential in applications for large molecules/periodic systems. Currently, there are significant efforts contributed toward the continuous development of this method in order to improve NN ability to fit larger molecular systems. In this talk, previous studies are discussed in term of advantages and limitations, and potential advancements are additionally suggested for future implementation of NN to improve its application in large molecular systems (specifically, a study of infinite 2D graphene will be discussed as an example).

In the second part, continuous interests toward graphene (as well as silicene) are shown by exploring their coordination interactions with 3d transition metals (Cr, Fe). The decorations of metal atoms in between two graphene layers (sandwich models) and on a planar (or buckled) silicene surface are carefully examined in term of binding energy and spin-polarization. Interestingly, the decoration of Fe is found to be either ferromagnetic or non-magnetic (depending upon the periodic distribution of Fe) from our spin-polarized DFT calculations. In the Cr case, the observations are different, in which the investigated models are all ferromagnetic. From such analysis, we can therefore make comparisons and conclusions on structural stabilities and magnetic properties.

Title: Synthetic Nonheme Metal-Oxygen Catalysts by Density Functional Theory: These Can Be Versatile too
Speaker:Dr Kyung-Bin Cho
Date:26 February 2013
Time:1:30pm – 3:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract:

Heme metal-oxygen utilizing catalysts (M=O, M-OO, M-OOH, M-HOOH) are found in many enzymes in Nature, such as cytochrome P450, horse radish peroxidase and nitric oxide synthase, just to name a few. There are also examples of nonheme metal-oxygen utilizing enzymes, such as naphthalene dioxygenase, homoprotocatechuate 2,3-dioxygenase and taurine:-ketoglutarate dioxygenase. These compounds catalyze common and essential reactions such as hydroxylation, epoxidation, desaturation and sulfoxidation. A given approach to understand the fundamentals of the reactions these compounds catalyze is to synthesize model systems. Our lab routinely produces and investigates the reactivities of such compounds, and this talk will give an overview of the theoretical calculations done in this area, in order to gain more insights than just experiments only could give.

Title: Cytochrome 450 and its Reactivity Patterns: What a Versatile Catalyst!
Speaker:Professor Sason Shaik
Date:26 February 2013
Time:10:30am – 12:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract:

Theory reveals the uncanny ways of cytochrome P450 to perform transformations like C-H hydroxylation, C=C epoxidation, heteroatom oxygenation, and C-C bond coupling, all via one active species! My talk will describe two-state reactivity (see Figure 1), proton coupled electron transfer (Figure 2), and catalysis by one or two water molecules, and cooperative reactivity.1

References :1 Shaik, S, Cohen, S., Wang, Y., Chen, H., Kumar, D. Thiel, W. Chem. Rev. 2010, 110, 949.

Title: Oxidative Coupling: Chemistry between Two “Nucleophiles”
Speaker:Professor Aiwen Lei
Date:22 February 2013
Time:10:45am – 12:15pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Professor Loh Teck Peng
Abstract:

Our research focuses on developing novel and efficient bond-formation methods catalyzed by transition metals. Currently, we are interested in the oxidative coupling, which avoids difficult oxidative addition step and makes bonds between two nucleophiles. As an important character of our research, in-depth understanding toward the reactions is the other focus. Recently, we revealed a second transmetallation reaction, which could occur in the Pd-catalyzed coupling reaction as a fundamental step. In addition, kinetic studies in our laboratory quantitatively disclosed the rate of reductive elimination of Csp2-Ni-Csp2.

References [1] Shi, W.; Liu, C.; Lei, A. W. Chem. Soc. Rev. 2011, 40, 2761. [2] Liu, C.; Zhang, H.; Shi, W.; Lei, A. W. Chem. Rev. 2011, 111, 1780. [3] Liu, Q.; Zhang, H.; Lei, A. W. Angew. Chem. Int. Edit. 2011, 50, 10788. [4] Liu, C.; Jin, L. Q.; Lei, A. W. Synlett 2010, 2527.

Title: Motivational tools in challenging olefin metathesis reactions
Speaker:Professor Karol Grela
Date:8 February 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Dragoslav Vidovic
Abstract:

 

Ruthenium-catalyzed olefin metathesis reactions represent an attractive and powerful transformation for the formation of new carbon-carbon double bonds [1]. This area is now quite familiar to most chemists as numerous catalysts are available that enable a plethora of olefin metathesis reactions [2]. However, some transformations, such as formations of substituted double bonds, formations of strained rings, low-temperature metathesis, etc. still remain challenging [3]. This limitation can be solved by designing new more active catalysts [4] or searching for new reaction conditions [5].

Title: Asymmetric Synthesis of Chiral Aromatic Compounds by Rhodium-Catalyzed [2+2+2] Cycloaddition
Speaker:Professor Ken Tanaka
Date:7 February 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:

 

The development of novel rhodium-catalyzed enantioselective [2 + 2 + 2] cycloaddition reactions for the asymmetric synthesis of chiral aromatic compounds will be disclosed. This process enables the catalytic enantioselective construction of axial, planar, and helical chiralities.

Title: Ionic Liquids – Green Solvents for Energy Storage
Speaker:Dr Slobodan Gadžurić
Date:5 February 2013
Time:4:00pm – 5:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Dragoslav Vidovic
Abstract:

One of the most promising areas of research in new green technologies is the application of neoteric solvents, such as ionic liquids (ILs). This group of solvents also includes supercritical carbon dioxide and aqueous biphasic systems. Due to their unique properties, ionic liquids are applied in the many fields of chemistry, technology and pharamceutical industry. As non-coordinating medium, they are solvating and dissolving a large number of organic and inorganic substances. They are non-volatile, non-flammable, thermal stable and are relatively undemanding to manufacture. In the current understanding, ionic liquids contain large, organic cations with a variety of anions and melt at or below 100 °C. The properties of both cation and anion are useful tools for fine-tuning the properties of the resulting ionic liquid for desired solvent properties. Due to the negligible vapor pressure of ILs, these substances are referred as green solvents. However, the high viscosity of pure ILs is often a problem for their application as electrolytes. To solve this, an effort was made to use the mixtures of ILs and various molecular liquids with low viscosity.

The physical-chemical characterization is an essential for understanding and the application of the ionic liquids in the analytical chemistry, organic synthesis, industrial processes and environmental protection. Since the existing literature data describing properties of ionic liquids are insuficient and rather scarce, we determined densities, conductivity and viscosity of several newly synthesized or commercial ionic liquids and their binary mixtures with propylene carbonate, N,N-dymethilformamide and N-methylformamide at atmospheric pressure and temperatures from 293.15 to 353.15 K. Also, spectroscopic properties upon addition of thermochromic substance, such as cobalt(II), were investigated. Possible application of ionic liquids for passive solar energy storage and protection of agricultural greenhouses from overheating was discussed.

Title: Functional molecular scaffolds: materials for the 21st Century
Speaker:Professor George Gruner
Date:30 January 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Zhao Yanli
Abstract:Ever since the Bronz Age, materials played a fundamental role in ushering in industrial revolutions. This was also true in the last Century, when crystalline materials such as silicon, and devices such as the transistor were the key for the emergence of the age of electronics. The challenges of today require new materials with fundamentally new properties. I will describe materials structures that have targeted functionalities. The architecture is that of an electrically conducting carbon nanotube scaffold, onto which molecules and nano-scale materials – such as the light harvesting molecule porphyrine, polymers, quantum dots, and nanoparticles with high electrochemical activity or biological receptor molecules - can be attached. While such “materials structures” will play an important role in a whole range of emerging industries, this talk will review results and the value propositions in the areas of renewable energy, printed electronics and biotechnology.
Title: Synthesis of Saxitoxins
Speaker:Professor Kazuo Nagasawa
Date:28 January 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Shunsuke Chiba
Abstract:Saxitoxin (STX) and its analogs are potent neurotoxins isolated from paralytic shellfish. These toxins selectively bind to the voltagegated sodium channels (NaVChs), and inhibit neuronal cell depolarization processes by blocking the influx of sodium ions. We recently have succeeded in total synthesis of (+)-saxitoxin and its natural analogs.1-4 In our synthesis, construction of saxitoxin skeleton by using conformationally controlled guanidine cyclization is the key step, which led to the synthesis of the fully protected saxitoxinol. This key intermediate enables us to access the (+)-saxitoxin and (+)-gonyautoxin III (Figure). Moreover, varieties of artificial saxitoxin derivatives were synthesized from the protected saxitoxinol intermediate. Theses syntheses and their inhibitory activities against some NaVCh subtypes will be presented.
Title: Structural and Dynamic Properties of Ionic Liquids
Speaker:Professor Yanting Wang
Date:25 January 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Hajime Hirao
Abstract:

Ionic liquids (ILs) have very wide perspective industrial applications. Understanding their structural and dynamic properties is essential for the systematic design of ILs to meet specific application requests. Ionic liquids with intermediate nonpolar cationic side-chain lengths are known to have nanoscale spatial heterogeneities with nonpolar tail domains separated by a continuous polar network. Based on this knowledge, our most recent molecular dynamics simulations have the following discoveries. 1) When driven by an external electric field, the ion cage structure was found to play an essential role in determining the structural and dynamic properties of the IL system. With a weak or moderate electric field (0 ~ 107 V/m), the external electric field is too weak to modify the ion cage structure and thus the changes of structural and dynamic properties are negligible. With a strong electric field (107 ~ 109 V/m) applied, ion cages expand and deform apparently, leading to faster and anisotropic dynamics. In addition, the Einstein relation connecting diffusion and mobility breaks down at strong electric fields.

2) When the nonpolar cationic side chain is sufficiently long, due to the stronger van der Waals interactions between the side chains, the structure of ionic liquids goes through a transition from spatially heterogeneous to liquid crystalline-like.

3) Only by replacing one of the hydrogen atoms on the terminal methyl group with a hydroxyl group, ILs can no longer aggregate to form separated nonpolar tail domains, instead hydroxyl groups form a rich number of hydrogen bonds with other groups, indicating that the hydroxyl substituent changes the IL system from an amphiphilic liquid to a polar liquid.

Title: Muscle and cardiac biophysics at LKCMedicine. Past results and a vision for the future
Speaker:Professor Michael Alan Ferenczi
Date:22 January 2013
Time:3:00pm – 4:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Xing Bengang
Abstract:One of the first laboratories to be established in the new medical school at NTU, Lee Kong Chian School of Medicine, is the Laboratory of Muscle Biophysics under the leadership of Professor Michael Ferenczi. Mike will describe the use of novel techniques to explore the molecular mechanism of contraction. Using fluorescent reporters of biochemical changes, the relationship between work, power output and ATP hydrolysis will be revealed, with millisecond time resolution. The technique will be shown to provide insight into the workings of the heart, namely how cardiac stretch enhances force generation. Cardiac muscle adapts in various ways to the demands made on it. One recently observed change is phosphorylation of the regulatory light chain. Mike will show how phosphorylation modifies cardiac behaviour, suggesting new approaches to modulate cardiac performance. Initial results from permeabilised muscle fibres and isolated myofibrils will be shown, together with the results of investigation into the mechanisms by which single point mutations in sarcomeric proteins give rise to hypertrophic cardiomyopathies, a cause of cardiac sudden death in young adults.
Title: Microfluidic Tools for Measuring the Composition and Reactivity of Particulate Matter
Speaker:Professor Charles Henry
Date:21 January 2013
Time:11:00pm – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Richard Webster
Abstract:The interest in airborne particulate matter monitoring has steadily gained interest due to effects of these aerosols on both climate and health. From a health perspective, epidemiological studies have established a direct correlation between ambient particle number density and mortality rates. The mechanisms surrounding these negative health outcomes are still poorly understood. From an atmospheric perspective, aerosols affect precipitation patterns, heating and cooling cycles, and visibility. In this presentation, a microfluidic systems that allow for measurement of particle composition and biological reactivity will be presented. Aerosols exhibit high temporal and spatial variability, making extended, routine analyses across broad geographic regions a necessity. Current composition monitoring techniques include filter extraction analyzed offline with ion (IC) or gas chromatography (GC), the particle-into-liquid-system (PILS) coupled directly to IC, and the aerosol mass spectrometer (AMS). None of these techniques possess the attributes needed for routine, widespread monitoring – inexpensive instrumentation, rapid analysis (< 5min), and/or the ability to monitor many species simultaneously. The current presentation will first discuss work focused on interfacing microchip capillary electrophoresis (MCE) with a small particle sampler to provide a device capable of inexpensive, routine aerosol monitoring. The system can measure common anions with detection limits of 10 nM and provide high resolution of critical aerosol components. The second part of this talk will focus on measuring the ability of particulate matter to react with model antioxidants using an microfluidic electrochemical sensor. The system has the ability to provide the highest temporal resolution measured to date for particle reactivity. Finally, the use of paper-based analytical devices for the measurement of particle composition will be discussed with an emphasis on detecting particulate metals in occupational health settings. Paper-based analytical devices are of significant interest in this application because they can detect low levels of metals while costing less than $0.02 for each assay.
Title: Exploiting Supramolecular Assemblies and Tailor-made Polymers for Responsive Nanoarchitectures: Fabrication, Characterization and Biomedical Applications
Speaker:Professor Holger Schönherr
Date:17 January 2013
Time:4:00pm – 5:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Ling Xing Yi
Abstract:In this contribution our recent efforts to exploit supramolecular assemblies and tailor-made polymers for the realization of responsive nanoarchitectures and versatile biointerfaces will be discussed. In particular, the template replication approach combined with polymer wetting or alternatively layer-by-layer (LBL) deposition of polyelectrolytes [1] will be contrasted with the self-organization of tailor-made enzyme-responsive block copolymers [2]. In addition, polymer brushes [3] and 3D microstructured substrates for cell-surface interactions [4] will receive attention to illustrate the breadth of research carried out presently in my laboratory. Template replication offers unique opportunities to design and fabricate nanostructures, which exceed the size range of molecules and selfassembly approaches, by faithful 1 : 1 replication. In this context we have developed new approaches to shape pores formed during anodization of Al by temperature modulation. The resulting pores, which possess modulated diameters along their length, have been successfully replicated using polymer wetting and layer-by-layer deposition of polyelectrolytes, resulting in novel, functional nanostructures (Figure 1a), yielding the first example of complex structures by LBL that possess concave and convex curvature. Self-organization of amphiphilic block copolymers represents an alternative pathway to obtain functional nanoscale structures, albeit with reduced degree of control regarding size distributions and dimensions. Vesicles of amphiphilic block copolymers belong to the class of polymeric, stimuli-responsive nanocarriers that are widely discussed in literature as promising drug delivery systems (Figure 1b, c). Due to their stable nature and versatile properties, they can also be used as storage compartments of active compounds in other biomedical applications, such as advanced wound dressings, where the release of antimicrobials and/or fluorescent markers as part of an indicator system of bacterial infection represents a central mode of action. The in situ detection and treatment of infections in scald or burn wounds is not only essential for proper healing as well as the prevention of scarring, but may contribute to reduce the spread of antibiotic resistance stemming from prophylactic administration of broadband antibiotics. In this context we synthesized and investigated assemblies of novel amphiphilic block copolymers, e.g. hyaluronic acid-block-e-polycaprolactone and hyaluronic acid-block-poly(lactic acid) copolymers (Figure 1b). Hyaluronic acid is the target for the enzyme hyaluronidase that is excreted by the bacterium staphylococcus aureus. Hence in an infected wound covered with a capsule-containing dressing, the capsules are opened by the bacterial enzymes, which signals selectively the infection and may administer potent antimicrobials.
Title: Chemistry of Cumulenes, R-N=C=C=C=O and R-N=C=C=C=S
Speaker:Professor Curt Wentrup
Date:17 January 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Roderick Bates
Abstract:Iminopropadienones, R-N=C=C=C=O 2 can be synthesized from several different precursors, including Meldrum’s acid derivatives 1, by either flash vacuum thermolysis (FVT) or microwave irradiation in solution. The former method is useful for spectroscopic characterization, and the latter for synthetic applications. The thioketene analogs, RN=C=C=C=S, have also been prepared and characterized. Important reactions include the formation of pharmaceutically important diazepinone derivatives 4 and quinolones 5. Other diazepines have been prepared photochemically via nitrene rearrangements.
Title: Pd-Catalyzed Asymmetric Allylic Substitution Reactions: Challenges & Opportunities
Speaker:Professor Hou Xuelong
Date:17 January 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Steve Zhou
Abstract:The term hybrid natural products arbitrarily designates the naturally occurring compounds consisting of two more fundamental metabolic units, such as amino acids, carbohydrates, polyketides, and terpenes. Importantly, emergent biological activities are often derived from such mixed structures, which also present intriguing synthetic challenges: For effective construction of the heterologous molecular architectures, new enabling synthetic strategies and tactics needed to be devised.1 Over the years, we have been interested in the total synthesis of such hybrid natural products, as they offer us good lessons, catalyzing exploration of new synthetic methods. The seminar will present some recent results associated with our synthetic efforts directed toward saptomycin B (1; an aromatic–sugar hybrid) 2 and seragakinone (2; an aromatic–isoprenoid hybrid).3 . 
Title: Lessons from Total Synthesis of Hybrid Natural Products: Saptomycin B and Seragakinone A
Speaker:Professor Keisuke Suzuki
Date:15 January 2013
Time:2:30pm – 4:00pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Chiba Shunsuke 
Abstract:The term hybrid natural products arbitrarily designates the naturally occurring compounds consisting of two more fundamental metabolic units, such as amino acids, carbohydrates, polyketides, and terpenes. Importantly, emergent biological activities are often derived from such mixed structures, which also present intriguing synthetic challenges: For effective construction of the heterologous molecular architectures, new enabling synthetic strategies and tactics needed to be devised.1 Over the years, we have been interested in the total synthesis of such hybrid natural products, as they offer us good lessons, catalyzing exploration of new synthetic methods. The seminar will present some recent results associated with our synthetic efforts directed toward saptomycin B (1; an aromatic–sugar hybrid) 2 and seragakinone (2; an aromatic–isoprenoid hybrid).3 . 
Title: Ligand-Accelerated C-H Activation Reactions: New Synthetic Disconnections
Speaker:Professor Jin-Quan Yu
Date:11 January 2013
Time:11:00am – 12:30pm
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Associate Professor Chiba Shunsuke 
Abstract:Pd(II)-catalyzed enantioselective and position-selective C–H activation reactions are developed using mono-N-protected chiral amino acid ligands. C–H activation intermediates are characterized, offering insights into the origin of the observed stereoselectivity. Most importantly, these chiral ligands are found to accelerate drastically C–H activation reactions, shortening the reaction time from two days to 20 minutes.
Title: Templated self-assembly and integration of complex structures
Speaker:Dr Heiko Wolf
Date:4 January 2013 
Time:3.30pm to 5.00pm 
Venue:NTU SPMS CBC Building Level 2, Conference Room
Host:Assistant Professor Ling Xing Yi
Abstract:A considerable fraction of novel nanomaterials is prepared as colloidal suspensions. The fabrication of devices from such materials requires methods for efficient and accurate integration of nanoscale objects from the liquid phase onto a solid surface. More complex device architectures may, in addition, entail the selective assembly of several different types of small objects into pre-defined locations or demand an assembly with the correct orientation when such objects are non-spherical. Here, we describe a technique that uses a combination of capillary assembly and printing with elastomeric stamps to fabricate defined particle arrays with high yield and accuracy. Capillary assembly is performed from an aqueous colloidal suspension by dragging the meniscus of the suspension over a 3D-structured template. Capillary forces trap the particles and drive them into their designated positions on the template. The template is a silicone elastomer replica of a 3D-structured silicon master. In a subsequent transfer step, the assembled particles are printed onto the target substrate. In order to demonstrate assemblies with increased complexity, templates and processes that allow for the oriented deposition of non-spherical nanoparticles were developed. Furthermore, the combination of different directed assembly steps offers the possibility to create even more complex structures based on different building blocks.