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)
안녕하세요. 이번주 목요일(4월 9일) 정규세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ======================================== 제 목 : Tracking Single Molecule and Particle 연 사 : 배성철 교수님(UNIST) 일 시 : 2015년 4월 9(목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) --------------------------------------- Tracking Single Molecule and Particle Tracking single molecule and particle is useful in characterizing active transport in relevant biological problems. Recent advances in fluorescence microscopy made possible to observe a single molecular event. However, there are many obstacles to track single molecule or particle in-vivo as well as in-vitro. Among them are low signal-to-noise ratio, photobleaching, and so on. In this talk, I will describe our recent works on fluorescence imaging to track active transport of single molecule and particle in living cells and hydrogel. Endosomal active transport within living cells has been observed with nanometer resolution in multiple cell lines and for different cargo types and their behavior was carefully analyzed with millions of tracking data. DNA transport in agarose networks driven by electric field has also been observed with 2-color fluorescence microscopy. The ends and centers of monidisperse DNA molecule were labeled separately and their positions and conformation have been analyzed with nanometer resolution.
안녕하세요. 다음주 목요일(3월 12일) 정규세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ========================= 제 목 : Chemical and Nano-tribological Properties of CH3-terminated 연 사 : 임민수 교수님(Slippery Rock University) 일 시 : 2015년 3월 12(목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------- Chemical and Nano-tribological Properties of CH3-terminated Films Molecular-scale boundary lubrication is inevitable for many modern day devices due to micrometer-/nanometer- sized shrinkage of their geometrical dimensions, including high-density computer hard disk drives (HDD) and microelectromechanical systems (MEMS). A self-assembled monolayer (SAM) of organic molecules is a good candidate to serve this demand. A SAM is a two-dimensional molecular array that is spontaneously organized by adsorption of amphiphilic organic molecules on a solid inorganic surface. Typically, an adsorbing molecule consists of a head group that initiates the molecule to anchor to a solid substrate surface, a methylene backbone chain that influences the packing density of a film by its length, and a terminal group that determines the surface properties of the thin film. The present study explores the chain-length dependent frictional properties of methyl (CH3-) terminated SAMs and mixed SAMs, desorption kinetics of SAMs in aqueous environment, and their thermally driven stability. Morphological and tribological properties were investigated with atomic force microscopy (AFM). Chain ordering of the thin films was analyzed with diffuse reflectance infrared fourier transform spectroscopy (DRIFT) prior to the friction measurements. Wettability of the films was measured with water contact angles to explore hydrophobic nature of the films.
안녕하세요. 다음주 특별세미나가 수요일(4월 1일) 오후 3시부터 330118호에서 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ========================= 특별세미나 제 목 : Carbon Materials for the Future 연 사 : Prof.Rodney S. Ruoff (UNIST) 일 시 : 2015년 4월 1일(수) 오후 3시 장 소 : 화학관 1층 강의실 (330118호) ------------------------- Carbon Materials for the Future I offer a personal perspective of what new carbon and related materials might be achieved in the future. These include ‘negative curvature carbons’, ‘diamane’ and related ultrathin sp3-bonded carbon films/foils,sp2/sp3-hybrid materials, and others. I also will discuss research on graphene and other carbons including speculating about future research opportunities based on the results shown. Of possible interest: 1. (a) Lu XK, Yu MF, Huang H, and Ruoff RS, Tailoring graphite with the goal of achieving single sheets, Nanotechnology, 10, 269-272 (1999). (b) Lu XK, Huang H, Nemchuk N, and Ruoff RS, Patterning of highly oriented pyrolytic graphite by oxygen plasma etching, Applied Physics Letters, 75, 193-195 (1999). 2. Zhu, Yanwu; Murali, Shanthi; Stoller, Meryl D.; Ganesh, K. J.; Cai, Weiwei; Ferreira, Paulo J.; Pirkle, Adam; Wallace, Robert M.; Cychosz, Katie A.; Thommes, Matthias; Su, Dong; Stach, Eric A.; Ruoff, Rodney S. Carbon-Based Supercapacitors Produced by Activation of Graphene. Science 332, 1537-1541 (2011). 3.Odkhuu, Dorj; Shin, Dongbin; Ruoff, Rodney S.; Park, Noejung; Conversion of Multilayer Graphene Into Continuous Ultrathin sp3-bonded Carbon Films on Metal Surfaces Density. Scientific Reports (2013), DOI: 10.1038/srep03276. 4. Ruoff, Rodney S. Personal perspectives on graphene: New graphene-related materials on the horizon. MRS Bulletin, 37, 1314-1318 (2012).
안녕하세요. 이번주 목요일(3월 5일) 정규세미나가 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ========================= 제 목 : Ideal probe single molecule experiments reveal the intrinsic dynamic heterogeneity of a supercooled liquid 연 사 : 팽기욱 교수님(성균관대학교) 일 시 : 2015년 3월 5(목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------- Ideal probe single molecule experiments reveal the intrinsic dynamic heterogeneity of a supercooled liquid The concept of dynamic heterogeneity and the picture of the supercooled liquid as a mosaic of environments with distinct dynamics that interchange in time have been invoked to explain the non-exponential relaxations measured in these systems. The spatial extent and temporal persistence of these regions of distinct dynamics have remained challenging to identify. Here, single molecule fluorescence measurements using a probe similar in size and mobility to the host o-terphenyl unambiguously reveal exponential relaxations distributed in time and space and directly demonstrate ergodicity of the system down to the glass transition temperature. In the temperature range probed, at least 200 times the structural relaxation time of the host is required to recover ensemble averaged relaxation at every spatial region in the system.