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 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. 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. 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.
안녕하세요. 다음주 정규세미나는 목요일(12월 11일) 4시 30분부터 330226호에서 더블헤더로 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ========================= 정규세미나1. 제 목 : Molecular basis of unexpected enantioselective resolutions of aminoalcohols by lipase and Development of novel Enzyme from high-throughput screening of metagenomic library 연 사 : 이혁 박사(한국화학연구원) 일 시 : 2014년 12월 11일(목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------- Molecular basis of unexpected enantioselective resolutions of aminoalcohols by lipase and Development of novel Enzyme from high-throughput screening of metagenomic library 1) Lipases Lipases (EC 220.127.116.11) are one of the most widely used biocatalysts in the fields of academic and industrial research because of their high levels of thermal and chemical stability. Most lipases resolve secondary alcohols in accordance with the “Kazlauskas rule” to give the R-enantiomer. In a similar manner toother lipases, Candida rugosa lipase (CRL) exhibits R-enantioselectivity towards2-heptanol, although the enantiomeric ratio (E)is low (E = 1.6). However, it has been observed unexpected enantioselectivity (i.e., S-enantioselectivity) (E = 58)of CRL towards N-Boc-4-aminobutan-2-ol, which has asimilar chain length to 2-heptanol. To develop a deeper understanding of themolecular basis for this unusual enantioselectivity, we have conducted a series of molecular modeling and substrate engineering experiments. The results of thesecomputational and experimental analyses indicated that a hydrogen bond between the Ser450 residue and the nitrogen atom of the carbamate group is critical to stabilize the transition state of the S-enantiomer. 2) Hab Mutase We have established a simple and efficient high-throughput screening (HTS) system to identify novel isomerization activity for aromatic compounds from soil metagenomic libraries. Based on this HTS approach, we have discovered and characterized a novel enzyme among 740,000 clones in metagenomic libraries. Then we attempted to develop a novel biotransformation reaction for organic synthesis. This enzyme was overexpressed in E. coli and tested for a biotransformation reaction in various reaction conditions for an optimization. The combination of reduction and isomerization was designed for an easy use of this reaction, and we prepared whole E. coli cell biocatalyst having dual activity. Using this biocatalyst, multi-step reaction with diverse aromatic compounds was successfully carried out to give rise to good yields. I will discuss the whole process from finding a novel enzyme to developing a new biotransformation. ========================= 정규세미나2. 제 목 : EGFR Inhibitors for Lung Cancer 연 사 : 이광호 박사(한국화학연구원) 일 시 : 2014년 12월 11일(목) 오후 5시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------- EGFR Inhibitors for Lung Cancer Erlotinib (Tarceva) & Gefitinib (Iressa) are currently in clinic use as epidermal growth factor receptor (EGFR) kinase inhibitors for non-small-cell lung cancer (NSCLC). However, their clinical efficacy is limited by both their mechanism-based toxicity and the development of drug-resistance mutations, including the gatekeeper T790M mutation. Unlike their quinazoline-based core scaffold, a new pyrimidine-based irreversible inhibitor has been identified for the EGFR gatekeeper T790M mutant specific activities. These pyrimidine-based EGFR inhibitors may provide improved therapeutic window and more effective clinical treatment for NSCLC patients.
안녕하세요. 다음주 정규세미나는 목요일(11월 27일) 4시 30분부터 330226호에서 더블헤더로 진행됩니다. 많은 참석 부탁드립니다. 감사합니다. ========================= 정규세미나1. 제 목 : Stereodefined N,O- and O,O-acetals: Synthesis and Application 연 사 : 이영호 교수(POSTECH) 일 시 : 2014년 11월 27일(목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------- Stereodefined N,O- and O,O-acetals: Synthesis and Application Developing new methodologies that can introduce molecular diversity with high chemical efficiency in a highly controlled manner represents a primary goal in synthetic organic chemistry. Due to their high reactivity and chemoselectivity, organometal catalysts may play a unique role. In this presentation, our achievements on the use of stereodefined allylic N,O-acetals and O,O-acetals as a key moiety. This unstable functional group was efficiently synthesized by the unprecedented Pd-catalyzed asymmetric hydroamination of allenes. Various examples on the aza- and oxacycle synthesis will be also introduced, which illustrate the use of these stereodefined N,O-acetals as a stereodiversity-generating element. This new synthetic method should be highly useful for both the target-oriented and the diversity-oriented synthesis of bioactive natural products and analogues. References: 1. Kim, H.; Lim, W.; Im, D.; Kim, D.; Rhee, Y. H. Angew. Chem. Int., Ed. 2012,51, 12055. 2. Kim, H.; Rhee, Y. H. J. Am. Chem. Soc. 2012, 134, 4011. 3. Lee, J.; Gupta, S.; Jeong, W.; Rhee, Y. H.; Park, J. W. Angew. Chem. Int., Ed. 2012,51, 10851. 4. Kang, S.; Kim, D.-g.; Rhee, Y. H, Chem. Eur-J.2014, in press. 5. Lim, W.;; Kim, J.; Rhee, Y. H, J. Am. Chem. Soc. 2014, 136, 13618. ========================= 정규세미나2. 제 목 : Iridium-catalyzed Borylation of Secondary C-H bonds Directed By a Hydrosilyl Group 연 사 : 조승환 교수(POSTECH) 일 시 : 2014년 11월 27일(목) 오후 5시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------- Iridium-catalyzed Borylation of Secondary C-H bonds Directed By a Hydrosilyl Group Keywords C-H functionalization, borylation, Iridium Iridium-catalyzed functionalization of C‒H bonds with bis(pinacolato)diboron (B2pin2) has become a practical method for the direct formation of boronate esters. Significant progress has been made on the borylation of sp2 C−H bonds, but the borylation of sp3 C‒H bonds is less developed. Compared to the borylation of sp2C‒H bonds, the borylation of sp3 C‒H bonds typically requires high catalyst loadings and excess of the saturated substrates. The regioselectivity of the borylation of sp3 C‒H bonds strongly favors reaction at primary C‒H bonds, making the functionalization of secondary C‒H bonds challenging. In this seminar, I will present a series of catalytic reactions that convert secondary sp3 C-H bonds of alkyl groups to C-B bonds. These reactions occur through metal-boryl complexes and metal-silyl complexes. This presentation will also include information on the properties of these complexes that lead to catalytic reactions and information on the properties and reactions of the organoboron product.
안녕하세요. 정규세미나는 11월 6일 4시부터 더블헤더로 두 건이 개최됩니다. 많은 참석 부탁드립니다.감사합니다. ========================= 정규세미나1. 제 목 : Chasing Phosphohistidine, “Dark Matter” in the Phosphoproteome 연 사 : 기정민 교수(UNIST) 일 시 : 2014년 11월 6일(목) 오후 4시 장 소 : 화학관 세미나실 (330226호실) ------------------------- Chasing Phosphohistidine, “Dark Matter” in the Phosphoproteome Jung-Min Kee Department of Chemistry, UNIST, 50 UNIST-gil, Ulsan 689-798, Korea My research program in chemical biology is aimed at driving innovations in biology and medicine by utilizing synthetic protein chemistry. I will discuss my recent work on phosphohistidine (pHis), an unstable protein post-translational modification (PTM). Although the importance of pHis in cell signaling and metabolism has been long recognized, the full scope and exact function of protein histidine phosphorylation is not clearly understood. It is mainly due to the chronic lack of adequate research tools to investigate the unstable PTM. We provided first glimpse at this “dark matter” in the phosphoproteome through the development of stable phosphohistidine (pHis) analogs and specific antibodies towards pHis-containing proteins. The antibodies enabled the first selective detection and isolation of pHis proteins from native cell lysates. The phosphoproteomic workflow for pHis was also developed by synergistic combination of immunoenrichment and bioinformatic tools, thereby opening new opportunities. ========================= 정규세미나2. 제 목 : A Catalytic Enantioselective Glycolate Aldol Reaction via Lewis Base Activation of Lewis Acids and A General Enantioselective Approach to the Chemical Synthesis of the Chlorosulfolipids 연 사 : 정원진 교수(GIST) 일 시 : 2014년 11월 6일(목) 오후 5시 장 소 : 화학관 세미나실 (330226호실) ------------------------- A Catalytic Enantioselective Glycolate Aldol Reaction via Lewis Base Activation of Lewis Acids and A General Enantioselective Approach to the Chemical Synthesis of the Chlorosulfolipids Won-jin Chung Department of Chemistry, GIST, Gwangju, Korea Part 1. A general, efficient, Lewis-base catalyzed enantioselective addition of glycolate-derived silyl ketene acetals to a wide range of aldehydes will be presented. Both syn- and anti-diastereomers are accessible without changing the catalyst or controlling the geometry of the silyl ketene acetal. Simple modification of the size of alkyl groups on the silyl ketene acetal is sufficient to reverse the stereochemical course of the addition. The observed diastereoselectivity and reactivity could be rationalized by the analysis of six open transition state structures with the aid of computational analysis. Part 2. A concise and general approach has been developed for the enantioselective synthesis of three structurally related chlorosulfolipids. Key advances include highly stereocontrolled additions to a,b-dichloroaldehydes, kinetic resolution of complex chlorinated vinyl epoxide intermediates, and Z-selective alkene cross metathesis of cis-vinyl epoxides. This strategy facilitated the synthesis of enantioenriched danicalipin A, mytilipin A, and malhamensilipin A in nine, eight, and eleven steps, respectively. References 1. Chung, W.-j.; Carlson, J. S.; Vanderwal, C. D. J. Org. Chem. 2014, 79, 2226–2241. 2. Chung, W.-j.; Vanderwal, C. D. Acc. Chem. Res. 2014, 47, 718–728. 3. Chung, W.-j.; Carlson, J. S.; Bedke, D. K.; Vanderwal, C. D. Angew. Chem. Int. Ed. 2013, 52, 10052–10055. 4. Denmark, S. E.; Chung, W.-j. J. Org. Chem. 2008, 73, 4582–4595. 5. Denmark, S. E.; Chung, W.-j. Angew. Chem. Int. Ed. 2008, 47, 1890–1892.
안녕하세요. 11월 4일 1층 330118호에서 세미나가 개최됩니다. 많은 참석 부탁드립니다. 감사합니다. ================================================== 세미나2. 제 목 : A Journey Towards Ligand-Enabled Sterically Hindered Cross-Coupling Reactions 연 사 : Fuk Yee (Michael) KWONG (The Hong Kong Polytechnic University) 일 시 : 2014년 11월 4일 (화) 오후 4시 30분 장 소 : 화학관 1층 첨단강의실 (330118호실) -------------------------------------------------- A Journey Towards Ligand-Enabled Sterically Hindered Cross-Coupling Reactions Catalytic cross-coupling process has emerged as one of the most straightforward and widespread used protocols for scientists to produce chemical modifications for assembling structurally unprecedented, yet materially and pharmaceutically attractive compounds. Indeed, these methods have revolutionized the way chemists to perform complex organic synthesis. At the center of these synthetic technologies, catalyst development which allow selective bondcleavage/-construction using relatively unreactive, yet rich-feedstock in nature components would be highly attractive. Thus, catalyst exploration and development is particularly central to contemporary catalysis research for innovative organic synthesis.
안녕하세요. 세미나 공지드립니다. 11월 3일 330226호에서 세미나가 개최됩니다.많은 참석 부탁드립니다. 감사합니다. ================================================== 세미나1. 제 목 : Asymmetric hetero-Michael reaction of α,β-unsaturated carboxylic acid derivatives 연 사 : Yoshiji Takemoto (Graduate School of Pharmaceutical Sciences, Kyoto University) 일 시 : 2014년 11월 3일 (월) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) -------------------------------------------------- Asymmetric hetero-Michael reaction of α,β-unsaturatedcarboxylic acid derivatives Chiral oxygen-containing heterocycles such as isoxazolines, isoxazolidines, chromans, and dihydrobenzofurans can be found in numerous natural products and biologically active compounds. O-Heterocycles bearing amide moiety, in particular, such as roxifiban and erythrococcamide, exhibit pharmaceutically important activities, and the related carboxylic acids, such as acivicin and raxofelast, have been used as biological tools for drug discovery.Significant efforts have been focused on development of synthetic methods capable of providing facile access to these materials, but no successful reactions with unsaturated amides and carboxylic acids have been reported. Bifunctional hydrogen bond (HB)-donor organocatalysts have now come to represent a particularly promising approach to accomplishhighly enantioselective reactions, although there is still a strong drive to improve upon their catalytic activities and expand the scope of applicable reactions. We envisaged that improvements to the HB-donating ability could activate the poorly reactive Michael acceptor, and that this would be more important for an effective cyclization than increasing the basicityof the catalyst to activate the O-nucleophile. In the lecture, we report the asymmetric intramolecular oxa-Michael (AIOM) reaction of unactivated α,β-unsaturated amides and esters using powerful HB-donor organocatalysts.1)Furthermore, the products obtained from this reaction have been used for the straightforwardasymmetric synthesis of several natural products and biologically important compounds. We will also describe a new synthetic method for the AIOM reaction of α,β-unsaturated carboxylic acids using a dual arylboronic acid-aminothiourea catalytic system. We found that aminoboronic acid could be used to facilitate the intramolecular aza- and oxa-Michael reactions of α,β-unsaturated carboxylic acids. In addition, the combination of an arylboronic acid with a chiral aminothiourea provided the desired heterocycles in high yields and ee’s.2)The overall utility of this dual catalytic system was demonstrated by a one-pot enantioselective synthesis of (+)-erythrococcamide B, which proceeded via sequential Michael and amidation reactions.