안녕하세요. 다음주 수요일(12월 30일) 세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Developing a new ultrafast proving tool : challenging the chemical- and electronic dynamics of energy storage and solar cell systems 연 사 : 서현욱 박사 (Centre for Free-Electron Laser Science) 일 시 : 2015년 12월 30일 (수) 오전 11시 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Developing a new ultrafast proving tool : challenging the chemical- and electronic dynamics of energy storage and solar cell systems Laser based VUV pulses produced via the High Harmonic Generation process (HHG) by table-top systems enabled access to VUV and soft X-ray photon energies in the laboratory. In addition, ultrashort pulse duration downs to the attosecond scale opened new possibilities in many scientific research fields of physics and chemistry. Here our newly developed HHG-driven time- and angle- resolved PES set-up will be presented. The new machine is based on an apertureless time-of-flight electron spectrometer and a femto-second table-top laser light source. The spectrometer is equipped with supplemental pumping ports to extend the operational pressure up to 10-4 mbar range. Recently, we have studied the HHG from the gas-filled waveguide when using mixtures of two rare gases (Ar and Ne) as a nonlinear gas medium. The admixing of Ne into Ar gas can improve the generation yields of harmonics under slight phase mismatching conditions by a factor of 2. It is attributed to an improvement of the phase matching in the gas mixture. Together with our new experimental set-up, our new observation on the improved efficiency of HHG process by using two rare gas mixtures will be presented.
안녕하세요. 다음주 목요일(12월 3일) 세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Self-Assembly of Nanoparticles and Functional Block-Copolymers 연 사 : 박소정 교수 (이화여자대학교) 일 시 : 2015년 12월 3일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Self-Assembly of Nanoparticles and Functional Block-Copolymers For the past few years, my group has made several important discoveries towards understanding binary self-assembly of nanoparticles and amphiphilic polymers. Based on these studies, we have developed new hybrid materials with interesting optical and magnetic properties. Furthermore, we have incorporated functional polymers such as conjugated polymers and DNA into amphiphilic structures, and showed that their properties can be drastically modified through self-assembly. These results demonstrate that amphiphilic self-assembly is a powerful tool not only for making complex nanoscale architectures but also for manipulating materials properties.
안녕하세요. 다음주 목요일(11월 26일) 세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Enantioselective Construction of α-Quaternary Cyclic Carbonyl Compounds by Catalytic Asymmetric Allylic Alkylation 연 사 : 김지민 교수 (전남대학교) 일 시 : 2015년 11월 26일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Enantioselective Construction of α-Quaternary Cyclic Carbonyl Compounds by Catalytic Asymmetric Allylic Alkylation The asymmetric construction of quaternary stereocenters is a topic of great interest in the organic chemistry community. Among the available methods that afford this motif, palladium-catalyzed decarboxylative allylic alkylation has proven particularly effective and, over the last decade, Stoltz group has pursued this strategy employing chiral phosphinooxazoline (PHOX) ligands. Recently, the group disclosed the highly enantioselective palladium-catalyzed decarboxylative allylic alkylation of readily available lactams and imides to form a number of 3,3-disubstituted pyrrolidinones, piperidinones, caprolactams and structurally related N-heterocyclic compounds. In addition, cyclobutanones were successfully implemented in the enantioselective allylic alkylation serving synthetic building blocks to access a variety of enantioenriched derivative compounds. In this seminar, the palladium-catalyzed asymmetric allylic alkylations in lactams, cyclic imides, and small rings such as cyclobutanones will be discussed. References 1. C. M. Reeves, C. Eidamshaus, J. Kim, B. M. Stoltz, “Enantioselective Construction of a-Quaternary Cyclobutanones by Catalytic Asymmetric Allylic Alkylation” Angew. Chem. Int. Ed. 2013, 52, 6718. 2. N. B. Bennett, D. C. Duquette, J. Kim, W.-B. Liu, A. N. Marziale, D. C. Behenna, S. C. Virgil, B. M. Stoltz, “Expanding Insight into Asymmetric Palladium-Catalyzed Allylic Alkylation of N-Heterocyclic Molecules and Cyclic Ketones” Chem. Eur. J.. 2013, 19, 4414. 3. D. C. Behenna, Y. Liu, T. Yurino, J. Kim, D. E. White, S. C. Virgil, B. M. Stoltz, “Palladium-Catalyzed Decarboxylative Allylic Alkylation of Lactams: Enantioselective Construction of Quaternary N-Heterocycles“ Nature Chem. 2012, 4, 130.
안녕하세요. 다음주 목요일(11월 19일) 세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Making Small Molecules/Large Molecules, It’s all Syntheses 연 사 : 김정곤 교수 (전북대학교) 일 시 : 2015년 11월 19일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Making Small Molecules/Large Molecules, It’s all Syntheses 1. Mechanism Guided Development of Robust C-H Amination. 2. Metal-free Hydrosilylation Polymerization In this seminar, two examples of organic and polymer syntheses based on catalysis are presented. In the first half, a mechanistic study driven development of highly active Rh(III) catalyzed C-H amination will be presented. The clear identification of a rate control factor on Cp*Rh(III) catalyzed amidation allowed us to develop a new type of amidating reagents. The new amidating reagent, 1,4,2-dioxazol-5-one is not only reactive but also has many favorable features of broad synthetic scope, safe operations, and scalability. The whole development process of the mechanistic investigation, finding new amino source, and scale-up study will be discussed. In the second half, the new route to polycarbosilanes using a non-metal catalyst is presented. Unique catalytic behaviors of boranes, especially B(C6F5)3, are of special interest. Its high and versatile reactivity has widely applied to areas ranging from hydrosilylation and reduction of simple substrates to biomass conversion into valuable hydrocarbons. Along with many interesting reactions and applications, making or manipulation of macromolecules by boranes is highly anticipated to bring new structures and properties. We recently showcased it by the first example of metal-free hydrosilylation polymerization between dienes and disilanes by B(C6F5)3, which successfully replaced precious transition-metal-based systems. Under the easy-to-handle and mild conditions, various combinations of dienes and disilanes produced polycarbosilanes with a broad range of structures and properties. Their distinctive reactivity and selectivity are discussed herein.  Park, Y.; Park, K. T.; Kim, J. G.*; Chang, S.* J. Am. Chem. Soc. 2015, 137, 4534.  Kim, D. W.; Joung, S.; Kim, J. G.*; Chang, S.* Angew. Chem. Int. Ed. 2015, Early View.
안녕하세요. 다음주 목요일(11월 12일) 세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Total Synthesis of Inostamycin A 연 사 : 강성호 교수 (KAIST) 일 시 : 2015년 11월 12일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Total Synthesis of Inostamycin A Inostamycin A has been isolated from the culture broth of a microorganism pertaining to the genus Streptomyces sp. MH816-AF15.1 In the isolation process, inostamycins B and C have also been found together. Their structures were assigned by NMR spectroscopy and later inostamycin A was confirmed by X-ray crystallography of its sodium salt. While inostamycin A has ethyl group at C2, inostamycin B is one-carbon less homolog with methyl substituent instead of the ethyl and inostamycin C corresponds to decarboxylated inostamycin A. Inosamycin A sodium salt is folded around the sodium ion coordinated with its two carboxyl oxygens, two hydroxyl oxygens at C9 and C17, carbonyl oxygen at C11, and ether oxygen between C13 and C16. The folding conformation is believed to be responsible for its various potent physiological properties as an ionophoric polyether antibiotic. Inostamycin A displays inhibitory activity against phosphatidyl inositol turnover and inositol transferase to prevent cell proliferation and transformation, antibacterial activity against Gram-positive bacteria, anti-HIV activity, and reversing effect on multidrug resistance in cancer cells. It also potentiates paclitaxel cytotoxicity, and induces arrest of cell growth at G1 and apoptosis in human small cell lung carcinoma Ms-1 cells.2Intrigued by its structural complexity and promising biological activities, we have been engaged in synthetic studies on inostamycin A. In this seminar, we present the first total synthesis of the natural product. References 1. M. Imoto, K. Umezawa, Y. Takahashi, H. Naganawa, Y. Iitaka, H. Nakamura, Y. Koizumi, Y. Sasaki, M. Hamada, T. Sawa, T. Takeuchi, J. Nat. Prod. 1990, 53, 8252. 2. M. Kawatani, M. Uchi, S. Simizu, H. Osada, M. Imoto, Exp. Cell Res. 2003, 286, 57.
안녕하세요. 이번주 목요일(10월 29일) 세미나가 진행됩니다. 많은 참석 부탁드립니다.감사합니다. ====================================== 제 목 : Therapeutic siRNAs for Human Disease 연 사 : Muthiah Manoharan, Ph.D (Alnylam Pharmaceuticals) 일 시 : 2015년 10월 29일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Therapeutic siRNAs for Human Disease Synthetic small interfering RNAs (siRNAs) act as therapeutic agents through the RNA interference (RNAi) pathway and are specific and potent inhibitors of gene expression. These agents may be designed to target disease pathways previously considered “undruggable”. Numerous proof-of-concept studies both in animal models of human disease and in clinical trials demonstrate the broad potential and therapeutic value of RNAi therapeutics. The major challenge for the successful development of systemically delivered RNAi therapeutics had been the efficient delivery into organs or tissues and cells of interest to elicit RNAi mediated knockdown of faulty genes and effective translation of these approaches into clinic. At Alnylam Pharmaceuticals, we have developed chemical modifications of siRNAs to provide them with “drug-like” properties. Furthermore, efficient liver delivery approaches have been developed and clinical trials are advancing with RNAi therapeutics formulated in lipid nanoparticles (LNPs) for intravenous administration. More recently, systemic delivery of therapeutic siRNAs to liver hepatocytes by subcutaneous administration has been achieved by conjugating chemically modified siRNAs with multivalent N-acetylgalactosamine (GalNAc) residues that are recognized by the asialoglycoprotein receptor (ASGPR). siRNA-GalNAc conjugates efficiently target and silence disease-causing genes produced in liver hepatocytes. Using this conjugation platform, Alnylam is advancing several RNAi agents specific for liver targets through pre-clinical and clinical development to address diseases with highly unmet medical need. Our progress with the chemistry of siRNAs, their conjugates and applications in several therapeutic areas will be presented.
안녕하세요. 다음주 목요일(10월 22일) 세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Characterizing nanoscale energy carrier transport for renewable energy applications: lithium ion battery, microbial fuel cell, and thermoelectrics 연 사 : 임종우 박사 (Stanford University) 일 시 : 2015년 10월 22일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Characterizing nanoscale energy carrier transport for renewable energy applications: lithium ion battery, microbial fuel cell, and thermoelectrics Renewable and clean energy generation and storage are one of society\'s greatest needs. In reality, many of renewable energy sources exist as different forms such as waste heat, sunlight, and wastewater, and thus require to develop a wide range of energy converting techniques. For example, solid-state thermoelectric modules can convert heat to electricity and bacteria in microbial fuel cells can directly convert chemical energy in organic matter to electricity while Li-ion batteries can reversely convert electricity to chemical energy. In particular, electrochemisty plays an important role in these techniques, such as batteries and microbial fuel cells. However, the complexity of electrochemically-driven reactions often made hard to improve the efficiency of these systems and warrants fundamental understanding. Here, we employ in-situ synchrotron-based spectro-microscopy to investigate the detailed kinetics and thermodynamics of electrochemical reactions while they take place. In this talk, I will present new insights on three important classes of renewable energy techniques : (1) lithium insertion in lithium iron phosphate olivine battery electrodes (2) single-bacterium level charge transfer in microbial fuel cell (3) electron and phonon transport in silicon thermoelectrics.
녕하세요. 다음주 수요일(10월 7일) 세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Local modes in vibrational (and rotational) spectroscopy 연 사 : Prof. Per Jensen (University of Wuppertal) 일 시 : 2015년 10월 7일 (수) 오후 3시 장 소 : 화학관 1층 강의실 (330118호실) -------------------------------------- Local modes in vibrational (and rotational) spectroscopy The talk is concerned with the description of highly excited vibrational and/or rotational states of molecules in terms of localized vibrations or local modes. Local mode effects are most common in molecules with multiple equivalent H-X bonds, which give rise to equivalent H-X local-mode stretching vibrations, and we discuss the local mode phenomenon using the spectra of such molecules as examples. In the local mode picture of molecular vibration, experimentally observed, initially unexpected near-degeneracies of vibrational states at high vibrational excitation, and of rotation-vibration states at high rotational excitation, can be explained relatively straightforwardly. The local mode theory predicts relations between the conventional “effective” rotation-vibration parameters whose values are determined in analysis of experimental molecular spectra in least-squares fittings to observed rotation-vibration transition frequencies or wavenumbers. It should be emphasized, however, that such relations are only valid for particular forms of the effective rotation-vibration Hamiltonian used in the spectral analysis. We illustrate the theory with examples of experimental spectroscopic work where local mode effects play an important role in the interpretation of the experimental findings. The fact that local-mode vibrations not only cause clustering of highly excited vibrational energy levels, but also of highly rotationally excited rotation-vibration energy levels, has been understood fairly recently. We briefly outline the theoretical background for this phenomenon and relate it to the existing experimental work.
안녕하세요 다음주 목요일(10월 1일) 세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Self-assembly of graphene oxide nanosheets induced by interfacial polyionic complexation 연 사 : Franklin Kim 교수 (Institute for Integrated Cell-Material Sciences, Kyoto University) 일 시 : 2015년 10월 1일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Self-assembly of graphene oxide nanosheets induced by interfacial polyionic complexation One of the critical challenges for the practical application of graphene and its derivatives is developing a robust and versatile assembly method which allows the construction of the nanosheets into functional macroscopic structures appropriate for integration with conventional real-life devices. An interesting characteristic of graphene oxide is that they often behave as charged macromolecules, and thus can readily interact with an oppositely charged polyelectrolyte to form a stable complex. In this report, we demonstrate how such complexation process could be utilized for directing the self-assembly of nanosheets. By confining the nanosheet-polyelectrolyte complexation at air-liquid or liquid-liquid interfaces, the nanosheets are successfully assembled into various mesoscale architectures including fibers, capsules, films, and even 3D porous foam-like structures. In particular, we introduce a novel “diffusion driven layer-by-layer” assembly and demonstrate its application for the construction of graphene oxide (GO) sheets into porous three-dimensional structures. The process utilizes the interaction of GO with branched polyethylenimine (b-PEI), a positively charged polyelectrolyte, to form a stable complex. Interestingly, when this reaction is confined at a liquid/liquid interface, we observe that the diffusion of b-PEI allows the GO/b-PEI complex formed at the interface to continuously grow into a foam-like framework with tunable porosity. Furthermore, the assembly process can be utilized in various configurations such as to create free-standing architectures with tailored shapes or patterned films on a substrate. The obtained GO structures are quite stable and can be reduced using various methods. This novel assembly method opens pathway to many useful nanosheet superstructures, and may be further extended to other types of nanomaterials in general.