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.
안녕하세요. 다음주 목요일(9월 24일) 세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Next Generation Energy Evolution Systems: Fuel Cells and Lithium Secondary Batteries 연 사 : 장지훈 박사 (Texas Material Institute and Materials Science and Engineering Program, The University of Texas at Austin) 일 시 : 2015년 9월 24일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Next Generation Energy Evolution Systems: Fuel Cells and Lithium Secondary Batteries The exhaustion of natural resources and the limitation of efficiency of the thermodynamic systems have led to numerous attempts to explore the alternative systems which are based on using sustainable, eternal and clean energy sources. Therefore, there have been several candidates for the replaceable energy evolution systems such as fuel cells, solar cells and lithium secondary batteries. In this talk, I briefly introduce the various efforts in development of electrode materials for such energy evolution systems, especially fuel cells and lithium secondary batteries.
안녕하세요. 다음주 월요일(9월 21일) 세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Rational Design of Metal Ligands and Chiral Sensors 연 사 : 김현우 교수님 (KAIST) 일 시 : 2015년 9월 21일 (월) 오후 4시 30분 장 소 : 화학관 1층 강의실 (330118호실) -------------------------------------- Rational Design of Metal Ligands and Chiral Sensors Over the years, the increasing knowledge of transition metal catalysis has resulted in an enormous advances of green chemical technologies, as exemplified by such processes as C-H functionalization, direct cross coupling, and cascade or multicomponent reactions. The so-called privileged ligands have been reported to enhance the catalytic activity of various transition metals. The ultimate goal of my research is to develop another class of privileged ligands and transition-metal catalysts. During the last several years of research, we have observed the remarkable reactivity of 2,2’-dihydroxy benzophenone, which is based on a new phosphorus ligand (briphos) and chiral sensors. More importantly, in order to explain the observed electronic properties of briphos, we have proposed a new concept, geometric control, to modulate the ligand property in addition to conventional steric and electronic control. With this new concept and our own synthetic tool, we hope to develop a privileged ligand structure and explore transition metal catalysis to discover unseen reactivity and selectivity. Moreover, our recent progress on the development of chiral sensors will be introduced. References: (1) Lee, A.; Kim, H. J. Am. Chem.Soc. 2015, 137, 11250. (2) Lee, A.; Ahn, S.; Kang, K.; Seo, M.-S.; Kim, Y.; Kim, W. Y.; Kim, H. Org. Lett.,2014, 16, 5490. (3) Seo, M. S.; Lee, A.; Kim, H. Org. Lett., 2014, 16, 2950. (4) Seo, M. S.; Kim, K.; Kim, H. Chem. Commun., 2013, 49, 11623 (Inside Cover)
안녕하세요. 이번주 목요일(7월 16일) 세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : New Adventures in Organic Chemistry: Synergistyc Catalysis, photoorganocatalytic and Heterogenous Chemistry 연 사 : Ramon Rios Torres (University of Southampton) 일 시 : 2015년 7월 16일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- New Adventures in Organic Chemistry: Synergistyc Catalysis, photoorganocatalytic and Heterogenous Chemistry
안녕하세요. 다음주 목요일(6월 4일) 정규세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Catalytic C−H Functionalization Reactions of Pyrazoles 연 사 : 주정민 교수 (부산대학교) 일 시 : 2015년 6월 4일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Catalytic C−H Functionalization Reactions of Pyrazoles Pyrazoles have been found in a growing number of new pharmaceuticals, agrochemicals, and ligands to transition metals. Thus, the development of methods for the synthesis of structurally diverse pyrazoles represents an important objective in organic synthesis. While catalytic C–H functionalization reactions have been dramatically expanded, applications to pyrazoles have been limited largely to arylation reactions along with a single example of alkynylation. Given that installation of alkyl groups to the pyrazole ring provides conformational flexibility, displaying improvement of physical and biological properties, a method for the C-alkylation of pyrazoles that does not depend on the use of a strong base would be highly desirable. We envisioned that the electronic effect rendered by the electron-withdrawing group should not only reduce the Lewis basicity of the N2 atom but also enhance the acidity of the C–H bond of pyrazoles, thus enabling a C–H alkylation using activated alkyl halides or pseudohalides. We have developed the first catalytic C–H allylation and benzylation of pyrazoles that occurs with high regioselectivity by taking advantage of synthetically useful electron-withdrawing groups, such as nitro, ester, and chloro groups. Readily available allyl acetates and benzyl chlorides are employed in this reaction as the alkyl donors to provide C5-allylated and benzylated pyrazole compounds in high yields. The C–H allylation and benzylation reactions by the Pd complex derived from Pd(OAc)2 and PPh3 can be carried out under practical laboratory conditions without operational difficulties involving the handling of air and moisture sensitive reagents and special equipment to procure cryogenic conditions. This approach, not requiring strong base-promoted reaction conditions, will be useful to provide rapid access to allylated and benzylated pyrazoles. Efforts to expand the substrate scope of alkyl halides will be described as well. References  Bae, S.; Jang, H.-L.; Jung, H.; Joo, J. M. J. Org. Chem. 2015, 80, 690.
안녕하세요. 이번주 목요일(5월 21일) 정규세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Highly Efficient Inorganic Organic Hybrid Perovskite Solar Cells 연 사 : 전남중 박사 (한국화학연구원) 일 시 : 2015년 5월 21일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Highly Efficient Inorganic Organic Hybrid Perovskite Solar Cells One of the challenges of the scientific community working in green energy is to fabricate inexpensive and highly efficient solar cells to convert solar energy, the cleanest and most abundant renewable energy source available on Earth, into usable electrical energy. Recently, inorganic-organic hybrid perovskites as light harvesters have been considered as promising candidates for next generation solar cells due to the combination of superior optical properties with the opportunities for inexpensive, solution-based device fabrication. In this presentation,I will talk about the efficient hole-transporting materials based on pyrene arylamine and spiro-OMeTAD derivatives. Furthermore, solvent-engineering technology for the extremely uniform and dense perovskites layers will be introduced.Finally, the possibility of chemical combination of methylammonium lead iodide (MAPbI3), methylammonium lead bromide (MAPbBr3) and formamidinium lead iodide (FAPbI3) materials for the application to efficient solar cellswill be introduced.Our results showed that chemical and process engineering leads to a remarkable improvement of the inorganic-organic hybrid solar cells.
안녕하세요. 월요일(5월 18일) 특별세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : The Influence of Chirality on Polymers: from Optical Switches to Vapor Sensing 연 사 : Bruce M. Novak (The University of Texas at Dallas) 일 시 : 2015년 5월 18일 (월) 오전 11시 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- The Influence of Chirality on Polymers: from Optical Switches to Vapor Sensing Chirality is deeply embedded in the intricate processes of nature. Less explored is the influence chirality has on the properties of synthetic materials. Asymmetry’s impact is typically minor when dealing with random coil materials but becomes an overarching driver on the properties of polymers that adopt defined structures. Helical chains are the focus herein. Carbodiimides are a unique class of monomers that can be polymerized using transition metal catalysts to yield conformationally-stable helical polymers. By up fitting the metal centers with chiral ligands polycarbodiimides having a preferred screw-sense can be formed. These optically active polymers show highly unusual optical switching, self-assembly, surface, and bulk phase vapor sensing properties. The preparation and properties of chiral polycarbodiimides will be discussed.
안녕하세요. 다음주 목요일(5월 14일) 정규세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================== 제 목 : Observation and Analysis of Stochastic Iridium Oxide (IrOx) Single Nanoparticle Collisions on Ultramicroelectrode 연 사 : 권성중 교수님 (건국대학교) 일 시 : 2015년 5월 14일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------- Observation and Analysis of Stochastic Iridium Oxide (IrOx) Single Nanoparticle Collisions on Ultramicroelectrode We describe the electrochemical detection of single iridium oxide nanoparticle (IrOx NP) collision at a less catalytic electrode surface such as the NaBH4-treated Pt or the bare Au. We could observe the single NP collision through the enhanced current by electrocatalytic redox recycling. The overall current transient consists of repeated current spikes, superimposed on a current decay to reach a steady-state value. The current responses were caused by random individual events as a function of time rather than the usual continuous current caused by an ensemble of a large number of events. The height and frequency of the peak current are proportional to the applied potential and the particle concentration. The current is very sensitive to the material and surface state of the measuring electrode.