[세미나 공지] - 2014년 6월 20일(금) ========================= 제 목 : Interfacial interactions in surface chemistry 연 사 : Dr.JUNG, Jaehoon(RIKEN Advanced Science Institute, Hirosawa) 일 시 : 2014년 6월 20일 (금) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------- Interfacial interactions in surface chemistry JUNG, Jaehoon RIKEN Advanced Science Institute, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan e-mail: firstname.lastname@example.org Interfacial interaction has long served as a key element to get fundamental insights into surface science and related chemical phenomena. Understanding interfacial interaction is, therefore, of great importance to achieve robust predictability and high controllability in a variety of applications. Herein, we discuss the role of interfacial interaction in (i) fabricating a well-ordered molecular superstructure on metal surface, (ii) controlling chemical reactivity of ultrathin oxide film grown metal substrate, and (iii) introducing a novel functional group to the basal plane of graphene grown on metal substrate. Computational study based on density functional theory (DFT), in close conjunction with scanning tunneling microscopy (STM) experiment at atomic spatial resolution, has been mainly performed to unveil the influence of a broad range of interfacial interactions on geometric and electronic features of various surface species. Firstly, we successfully achieved a two-dimensional molecular superstructure of a fluorinated fullerene (C60F36) on Au(111) in a highly ordered manner. In STM experiment, we observed that the molecules in the well-ordered region are composed of only theC3 isomer, despite the existence of three isomers (C3,C1, and T). The DFT results revealed that the adsorption and lateral orientations of individual C60F36molecules in the superstructure are determined by the localized distribution of LUMO and by intermolecular electrostatic interactions, respectively. We expect that such well-ordered molecular film with high electron affinity might be useful to achieve a uniformn-type semiconducting molecular component in organic electronic device. Secondly, we demonstrated that the chemical reactivity for water dissociation on an ultrathin MgO film grown on Ag(100) substrate depends greatly on film thickness and is enhanced as compared to that achieved with their bulk counterpart. The change in the chemical reactivity of ultrathin MgO film depending on the film thickness can be explained by the interaction strength between the oxide and metal interface layers. Therefore, the manipulation of the local structure at the oxide-metal interface plays a pivotal role in controlling the chemical reactivity of ultrathin oxide film.[3a] We have recently presented that the chemical reactivity of MgO/Ag(100) for the dissociation of individual water molecules can be systematically controlled by interface dopants over the film thickness.[3b]We introduced the 3d transition metal dopants (Sc ~ Zn) into the oxide-metal interface due to the high tunability with a number of d electrons. DFT calculations revealed that the adhesion at the oxide-metal interface can be addressed by the interaction between a dopant and the oxide layer with aid of ligand field theory and is linearly correlated with the chemical reactivity of the oxide film. Our study provides not only profound insight into the chemical reactivity control of ultrathin oxide film but also an impetus for investigating ultrathin oxide ﬁlms for a wider range of applications. Lastly, we suggest, for the first time, that the atomic oxidation of graphene grown on a metal substrate results in the formation of graphene enolate, i.e., negatively charged oxygen adsorbed at ontop position on its basal plane, which is strikingly different from the formation of epoxy groups, i.e., adsorption of atomic oxygen at bridge position, on free-standing graphene and on graphite. Whereas the enolate is the transition state between two nearest epoxides both on graphene and on graphite, we revealed that improved interfacial interaction between graphene and metal substrate during atomic oxidation plays a crucial role not only in the formation of graphene enolate as a local minimum but also in stabilizing it over the graphene epoxide. To conclude, our studies open up a new vista for the design of novel materials of new potentials with desired functions based on the deep insight into the a wide range of interfacial interactions and its fine control. T. K. Shimizu§, J. Jung§, T. Otani, Y.-K. Han, M. Kawai, and Y. Kim, ACS Nano 6, 2679 (2012). [§equally contributed]. (a) H.-J. Shin, J. Jung, K. Motobayashi, S. Yanagisawa, Y. Morikawa, Y. Kim, and M. Kawai, Nat. Mater. 9, 442 (2010); (b) J. Jung, H.-J. Shin, Y. Kim, and M. Kawai, Phys. Rev. B 82, 085413 (2010). (a) J. Jung, H.-J. Shin, Y. Kim, and M. Kawai, J. Am. Chem. Soc. 133, 6142 (2011); (b) J. Jung, H.-J. Shin, Y. Kim, and M. Kawai,J. Am. Chem. Soc. 134, 10554 (2012). J. Jung, H. Lim, J. Oh, and Y. Kim, J. Am. Chem. Soc.submitted (2014).
이번주 목요일(6월 5일)에 세미나가 개최됩니다. 많은 참석 부탁드립니다.감사합니다. ========================= 제 목 : Moving Photodynamic Action into the 21st Century 연 사 : prof. Engin Umut Akkaya(Bilkent University) 일 시 : 2014년 6월 5일 (목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------- Moving Photodynamic Action into the 21st Century Engin U. Akkaya* email@example.com Department of Chemistry and UNAM-National Nanotechnology Research Center, Bilkent University, 06800 Ankara, Turkey. Our research group has contributed to the development of molecular logic gates over the years. However in recent years, the need to move molecular logic from the realm of intellectual exercise to practicality became an urgent matter. We, among a few others are convinced that the first unequivocal application will present itself in the nanomedicine field. One particular field of inquiry which could benefit from such fusion of ideas is photodynamic therapy. Photodynamic therapy (PDT) is a noninvasive method of treating malignant tumors and age-related macular degeneration, and is particularly promising in the treatment of multidrug-resistant tumors. The PDT strategy is based on the preferential localization of certain photosensitizers in tumor tissues upon systemic administration. The sensitizer is then excited with red or near infrared (NIR) light, generating singlet oxygen (1O2) and thus irreversibly damaging tumor cells. Current practice of PDT is limited to a few functionalized porphyrins and related compounds, however these are not considered to be ideal photosensitizers for use in PDT. Among the limitations, the most prominent is the low extinction coefficient of porphyrins in the body’s therapeutic window (650–800 nm).. As a consequence, many research groups worldwide are engaged in efforts to develop better sensitizers. One important aspect is the tight control of the delivery of cytotoxic singlet oxygen to be produced. In an earlier design, we proposed a sensitizer which behaves as an “AND” logic gate. Later, we proposed a demultiplexer design which can switch from therapeutic to diagnostic mode autonomously. The other path we are following is trying to find alternative excitation protocols for photodynamic action. The methodologies which we are currently evaluating are, chemiluminescence, persistent luminescence, and direct production of singlet oxygen. Our recent progress in these fields of research will be presented. References \'Selective Manipulation of ICT and PET Processes in Styryl-Bodipy Derivatives: Applications in Molecular Logic and Fluorescence Sensing of Metal Ions\' Ö. A. Bozdemir, et al., J. Am. Chem. Soc., 2010,132, 8029-8036. \'From Virtual to Physical: Integration of Chemical Logic Gates\' R. Guliyev, Ş . Öztürk, Z. Köstereli, E. U. Akkaya, Angew. Chem. Int. Ed., 2011, 50, 9826-9831. \'Designing Excited States: Theory-Guided Access to Efficient Photosensitizers for Photodynamic Action\' Y. Çakmak, et al., Angew. Chem. Int. Ed., 2011,50, 11937-11941. \'Cascading of Molecular Logic Gates for Advanced Functions: A Self-Reporting, Activatable Photosensitizer\' Erbas-Cakmak, S.; Akkaya, E. U., Angew. Chem. Int. Ed.2013, 52, 11364.
이번주 목요일(4월10일)에 세미나가 개최됩니다.
많은 참석 부탁드립니다.감사합니다.
제 목 : NOx storage-reduction (NSR) catalysts for diesel emissions control:
Toward the understanding of sulfur poisoning mechanism
연 사 : 김도희 교수(서울대학교)
일 시 : 2014년 4월 10일(목) 오후 4시 30분
장 소 : 화학관 세미나실 (330226호실)
NOx storage-reduction (NSR) catalysts for diesel emissions control:
Toward the understanding of sulfur poisoning mechanism
이번주 목요일(4월3일)에 세미나가 개최됩니다. 많은 참석 부탁드립니다.감사합니다. ========================= 제 목 : The Excited-States Dynamics of Single-Walled Carbon Nanotubes Wrapped by Ionic Conjugated Polymers 연 사 : 박재홍 교수(National Renewable Energy Laboratory (NREL), Chemical and Materials Science Center) 일 시 : 2014년 4월 3일(목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------- The Excited-States Dynamics of Single-Walled Carbon Nanotubes Wrapped by Ionic Conjugated Polymers Park, Jaehong National Renewable Energy Laboratory (NREL), Chemical and Materials Science Center Rationally designed, highly charged polymers are used to effectively wrap and disperse single-walled carbon nanotubes (SWNTs) in solution. When applied to samples of SWNTs that are enriched in a single chirality, the resulting polymer-wrapped SWNT hybrids are used to investigate previously unidentified carbon nanotube excited states and the potential of these supramolecular assemblies for light-to-fuel energy conversion reactions. Highlights include femtosecond pump-probe transient absorption spectroscopic experiments that identify, for the first time, microsecond-lived SWNT intrinsic excited-state as a function of local dielectric environment and dispersing agents, and demonstrate photoinduced electron transfer dynamics between a SWNT and a semiconducting polymer where we fully characterize the charge-separated products, and the dynamics of charge separation and recombination.
다음주 목요일(3월27일)에 세미나가 개최됩니다. 많은 참석 부탁드립니다.감사합니다. ========================= 제 목 : Torsionally-Responsive Molecules and Assemblies: Mechanism-Based Design of Fluorescent Sensors and Switches 연 사 : 이동환 교수(서울대학교) 일 시 : 2014년 3월 27일(목) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------- Torsionally-Responsive Molecules and Assemblies: Mechanism-Based Design of Fluorescent Sensors and Switches Dongwhan Lee Department of Chemistry, Seoul National University, Seoul, KOREA 151-747 firstname.lastname@example.org An increasing number of functional materials are built with π-conjugated chemical architectures. The practical utility of such constructs derives from rich optical and electrochemical properties that are inherent to their extended electronic structures, and the ability to manipulate them by either covalent or non-covalent synthetic modifications. Taking inspirations from the mode of operation of certain transmembrane protein complexes, we have devised a simple mechanical coupling scheme that correlates torsional motions of multiple aromatic groups that interact through a symmetric array of hydrogen bonds. The assembly and disassembly of multiple non-covalent contacts within such branched π-conjugation result in a dramatic switching of fluorescence properties. Taking this concept a step further, we are currently exploring stimuli-responsive chromophores and receptors, in which restricted torsional motions along the π-conjugated molecular backbone can be exploited for reactivity-based detection of biologically/environmentally relevant molecules and ions. In this presentation will be discussed the advent of this chemistry, its current progress, and future developments.
3월 21일 금요일에 해외석학 특별초청세미나가 개최됩니다. 많은 참석 바랍니다. ------------------------- 제 목 : Metal Cluster Catalyst for Transesterification and Amide Alcoholysis 연 사 : Prof.Kazushi Mashima(오사카 대학교) 일 시 : 2014년 3월 21일(금) 오후 4시 30분 장 소 : 화학관 세미나실 (330226호실) ------------------------- Metal Cluster Catalyst for Transesterification and Amide Alcoholysis Kazushi Mashima Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560‑8531, Japan. Email: email@example.com The ester moiety represents one of the most ubiquitous functional groups in organic compounds, serving as both key intermediate and protecting group in organic transformations. Among various esterification reactions established so far, one of the most convenient synthetic methods is transesterification, in which methyl or ethyl esters react with various alcohols to give the corresponding esters in one step. We developed -oxo-tetranuclear zinc cluster Zn4(OCOCF3)6O as an efficiently catalyst for transesterification, including chemoselective acylation of hydroxy group in the presence of aliphatic amino group, catalytic acetylation of alcohols and catalytic deacetylation of acetates. Because of mildness of the reaction conditions, these reactions have a high degree of functional-group tolerance. Recently, cobalt clusters mediate the same chemoselectivity for transesterification. Amide bond formation and degradation are also discussed.
3월 20일 목요일에 화학과 정규세미나가 개최됩니다.
많은 참석 부탁드립니다.감사합니다.
제 목 : 1-Sulfonyl-1,2,3-triazole: precursors for Rh(II)-azavinyl carbenes
연 사 : 유은정 교수(강원대학교)
일 시 : 2014년 3월 20일(목) 오후 4시 30분
장 소 : 화학관 세미나실 (330226호실)
1-Sulfonyl-1,2,3-triazole: precursors for Rh(II)-azavinyl carbenes
Eun Jeong Yoo
Department of Chemistry, Kangwon National University, Chuncheon 200-701, Republic of Korea
세미나가 이번주 목요일(3월 6일)에 개최됩니다.
많은 참석 부탁드립니다.감사합니다.
제 목 : Nanodevice-Based Molecular Detection: Focused on the Nanogap Biosensor
연 사 : 윤완수 교수님(성균관대학교)
일 시 : 2014년 3월 6일(화) 오후 4시 30분
장 소 : 화학관 세미나실 (330226호실)
Nanodevice-Based Molecular Detection: Focused on the Nanogap Biosensor
세미나가 다음주 화요일(1월 21일)에 개최됩니다. 많은 참석 부탁드립니다.감사합니다.========================= 제 목 : Exceptional catalytic activities of novel QDots formed by sub-nanometric metal (0) clusters연 사 : Prof. M.Arturo López-Quintela(University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain)일 시 : 2014년 1월 21일(화) 오후 4시 장 소 : 화학관 세미나실 (330226호실)------------------------- Exceptional catalytic activities of novel QDots formed by sub-nanometric metal (0) clusters M.Arturo López-Quintela Laboratory of Magnetism and Nanotechnology (Nanomag), Technological Research Institute, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain. Green chemistry and energy conversion are two of the main topics, which will be preferentially addressed in the next years in order to resolve two main problems of the current society: pollution and energy supply. In both areas the main difficulties, which have to be resolved, are related to the poor efficiency of the current catalysts. Although in the past years a lot of work has been dedicated to tackle such problem very little improvements were achieved. Therefore, there is an urgent need of looking for new strategies to overcome the current difficulties. We have seen very recently that Au metal clusters, formed by a few number of atoms, are extremely active catalysts, reaching in some cases enzymatic activities for aerobic oxidation reactions1. At the same time, such clusters, although formed by metal elements, they display semiconductor-like properties, whose band gap can be fine tuned by changing only one atom in the cluster, so that they could be also essayed as photocatalysts. We have indeed observed that clusters can also be used as very efficient photocatalysts for water splitting 2 and the destruction of pollutants. Therefore, the use of these few-atom compounds can open new ways to overcome the current difficulties found with the common catalysts. In this talk it will be presented an overview of the state-of-the art of the catalytic properties of clusters focussing into the fields of self-cleaning, water splitting and aerobic oxidation. We want to acknowledge the financial support of the MCI, Spain (MAT2010-20442; MAT2011-28673-C02-01), MINECO, Spain (MAT2012-36754-C02-01), Xunta de Galicia (Grupos Ref.Comp.,GRC2013-044, FEDER Funds) and Obra Social Fundación La Caixa (2012-CL097).