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.
안녕하세요. 이번주 목요일(5월 7일) 정규세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ====================================================== 제 목 : 신·재생에너지 기술 및 현황 연 사 : 성진기 박사님 (에너지기술평가원) 일 시 : 2015년 5월 7일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------------------------------------- 신·재생에너지 기술 및 현황 본 세미나에서는 신재생에너지의 정의 및 신재생에너지 국내외 현황 및 원별 기술개요 와 R&D 현황을 먼저 소개하고, 이어서 우리나라 신재생에너지 기술의 주요 제도 및 정책현황에 대하여 소개한 후 제4차 신재생에너지 기본계획에 대해 소개하고자 한다. 특히 제4차 신재생에너지 기본계획에는 추진현황 및 여건, 중장기 보급목표 및 정책방향, 세부추진과제, 그리고 투자계획 등에 대한 상세한 소개와 토의를 하고자 한다.
안녕하세요. 오늘(4월 22일) 특별세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ======================================== 제 목 : Novel Approach for Condensed-Phase Thermochemistry: Proposal and Applications of Harmonic Solvation Model (HSM) 연 사 :Hiromi Nakai 교수님 (와세다대학교) 일 시 : 2015년 4월 22(수) 오전 11시 장 소 : 화학관 1층 강의실 (330118호실) --------------------------------------- Novel Approach for Condensed-Phase Thermochemistry: Proposal and Applications of Harmonic Solvation Model (HSM) Over the 90 years’ history, quantum chemistry has been well developed and become a systematic treatment to evaluate a molecule’s electronic energy Eelec, and molecular properties such as geometric parameters and vibrational frequencies. Furthermore, the use of statistical mechanics under the ideal gas model (IGM) assumption enables estimation of the Gibbs energy G, which involves the enthalpy H and entropy S of a gaseous molecule. , (1) , (2) . (3) The subscripts elec, vib, rot, and trans denote electronic, vibrational, rotational, and translational contributions, respectively, to the energy and entropy. In many cases, except at extremely high/low temperatures and/or pressures, the IGM works well and reasonably reproduces the thermodynamic properties. The situation is more complicated in the liquid phase. Much effort has been devoted to developing solvation models to describe electrostatic interactions and non-electrostatic interactions such as Pauli repulsion, dispersion, and cavity formation energy. The self-consistent reaction field (SCRF) formalism is one of the most widely used models; it mainly focuses on the solvation free energy. The contribution of solvent effects obtained using the SCRF is normally added to the electronic energy using standard quantum chemical programs. Other contributions to the enthalpy and entropy are evaluated using the formalism based on the IGM. However, the molecular motion in the liquid phase is remarkably different from that in the gas phase. As a result, the IGM treatment fails to reproduce the condensed-phase thermochemistry and occasionally lead to unphysical behaviours. We have recently an alternative approach to calculate thermochemical parameters in the condensed phase, in particular, in the liquid phase.[1,2] The model represents translational and rotational motions of a solute as vibrations interacting with a cavity wall of solvents and treats all the degrees of freedom for nuclear motion as harmonic vibrations. Thus, we call it the harmonic solvation model (HSM). The computational cost of HSM is comparable with the conventional calculations for enthalpy, entropy, and Gibbs energy using the ideal gas model (IGM): namely, geometry optimization and frequency analysis are required in the quantum chemical calculations. The accuracy of the HSM is confirmed by applying to the standard formation reaction of liquid water, combustion reactions of liquid organic molecules, vapor–liquid equilibration, and dissolution of gaseous molecules. For example, the boiling point of water was reasonably described by the present HSM treatment, while the conventional IGM treatment failed to obtain a crossing of the two Gibbs energy curves for gaseous and liquid water (Fig. 1).  “Quantum chemical approach for condensed-phase thermochemistry: Proposal of a harmonic solvation model”, H. Nakai, A. Ishikawa, J. Chem. Phys., 141 (17), 174106 (9 pages) (2014). (DOI: 10.1063/1.4900629)  “Quantum chemical approach for condensed-phase thermochemistry (II): Applications to formation and combustion reactions of liquid organic molecules”, A. Ishikawa, H. Nakai, Chem. Phys. Letters, 624, 6–11 (2015). (DOI: 10.1016/j.cplett.2015.01.054)