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Geometrical Optimization Approach to Isomerization: Models and Limitations
Chang, Bo Y.,Shin, Seokmin,Engel, Volker,Sola, Ignacio R. American Chemical Society [etc.] 2017 The Journal of physical chemistry A Vol.121 No.43
<P>We study laser-driven isomerization reactions through an excited electronic state using the recently developed Geometrical Optimization procedure. Our goal is to analyze whether an initial wave packet in the ground state, with optimized amplitudes and phases, can be used to enhance the yield of the reaction at faster rates, driven by a single picosecond pulse or a pair of femtosecond pulses resonant with the electronic transition. We show that the symmetry of the system imposes limitations in the optimization procedure, such that the method rediscovers the pump-dump mechanism.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcafh/2017/jpcafh.2017.121.issue-43/acs.jpca.7b08767/production/images/medium/jp-2017-08767m_0004.gif'></P>
Moon, Jiwon,Baek, Heehyun,Kim, Joonghan American Chemical Society [etc.] 2016 The Journal of physical chemistry A Vol.120 No.46
<P>A recent spectroscopic experiment identified difluorothiophosphoryl nitrene (F2P(S)N) and found that it showed rich photochemistry. However, a discrepancy between the experimental results and the quantum chemical calculations was reported. Thus, high-level ab initio calculations using the coupled cluster singles and doubles with perturbative triples and second-order multiconfigurational perturbation theory were performed to elucidate this inconsistency. The discrepancy arose due to the failure to consider the triplet state of difluoro(thionitroso)phosphine (F2PNS). In this work, we identify that the global minimum of the system is the triplet state of F2PNS, which allows us to explain the inconsistency between the experimental and theoretical results. All calculated results give consistent results with the recent experimental results.</P>
Synthesis of 2-Vinylindole-3-Acetic Acid Derivatives via Cyanide-Catalyzed Imino-Stetter Reaction
Seo, Hong-Ahn,Cheon, Cheol-Hong American Chemical Society etc. 2016 Journal of organic chemistry Vol.81 No.17
<P>A new method for the synthesis of 2-vinyl-indole-3-acetic acid derivatives from aldimines, which are derived from 2-aminocinnamic acid derivatives and alpha,beta-unsaturated aldehydes, via a cyanide-catalyzed imino-Stetter reaction is described. Various types of 2-aminocinnamic acid derivatives and alpha,beta-unsaturated aldehydes could be used in this protocol, and the desired 2-vinyl substituted indole-3-acetic acid derivatives were obtained in high yields. This cyanide-catalyzed imino-Stetter reaction was further extended to the preparation of indole-3-acetic acid derivatives bearing a carboxylic acid functionality at the 2-position, using aldimines obtained from glyoxylates and 2-aminocinnamic acid derivatives.</P>
Shin, Dong Won,Guiver, Michael D.,Lee, Young Moo American Chemical Society [etc.] 2017 Chemical reviews Vol.117 No.6
<P>A fundamental understanding of polymer microstructure is important in order to design novel polymer electrolyte membranes (PEMs) with excellent electrochemical performance and stabilities. Hydrocarbon-based polymers have distinct microstructure according to their chemical structure. The ionic clusters and/or channels play a critical role in PEMs, affecting ion conductivity and water transport, especially at medium temperature and low relative humidity (RH). In addition, physical properties such as water uptake and dimensional swelling behavior depend strongly on polymer morphology. Over the past few decades, much research has focused on the synthetic development and microstructural characterization of hydrocarbon-based PEM materials. Furthermore, blends, composites, pressing, shear field, electrical field, surface modification, and cross-linking have also been shown to be effective approaches to obtain/maintain well-defined PEM microstructure. This review summarizes recent work on developments in advanced PEMs with various chemical structures and architecture and the resulting polymer microstructures and morphologies that arise for potential application in fuel cell, lithium ion battery, redox flow battery, actuators, and electrodialysis.</P>
Yu, Subeen,Cho, Eunjeong,Kim, Jimin,Lee, Sunwoo American Chemical Society etc. 2017 Journal of organic chemistry Vol.82 No.20
<P>A palladium-catalyzed decarboxylative coupling reaction was developed for the synthesis of 3-(1-alkynyl)-2-cyclohexen-1-ones. A variety of alkynyl carboxylic acids were coupled with 3-oxocyclohexenyl tosylates to afford the corresponding enynones in good to excellent yields. The developed catalytic system is phosphine free and showed good tolerance toward various functionalities such as chloride, cyano, nitro, ester, aldehyde, and alcohol groups. In addition, phenylpropiolic acid exhibited higher reactivity in the reaction with alkenyl toslyate than phenyl acetylene.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/joceah/2017/joceah.2017.82.issue-20/acs.joc.7b02175/production/images/medium/jo-2017-02175d_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jo7b02175'>ACS Electronic Supporting Info</A></P>
Moon, Jiwon,Kim, Joonghan American Chemical Society [etc.] 2016 The Journal of physical chemistry A Vol.120 No.38
<P>Density functional theory (DFT) and ab initio calculations, including spin-orbit coupling (SOC), were performed to investigate the spin-orbit (SO) effect on the molecular properties of tellurium halides, TeXn (X = F, Cl, Br, and I; n = 1, 2, and 4). SOC elongates the Te-X bond and slightly reduces the vibrational frequencies. Consideration of SOC leads to better agreement with experimental values. Moller-Plesset second-order perturbation theory (MP2) seriously underestimates the Te-X bond lengths. In contrast, B3LYP significantly overestimates them. SO-PBEO and multireference configuration interactions with the Davidson correction (MRCI+Q), which include SOC via a state-interaction approach, give the Te-I bond length of TeI2 that matches the experimental value. On the basis of the calculated thermochemical energy and optimized molecular structure, TeI4 is unlikely to be stable. The use of PBEO including SOC is strongly recommended for predicting the molecular properties of Te-containing compounds.</P>
Kim, Jin Woo,Kim, Yeonjoon,Baek, Kyung Yup,Lee, Kyunghoon,Kim, Woo Youn American Chemical Society [etc.] 2019 The Journal of physical chemistry A Vol. No.
<P>Accurate analysis of complex chemical reaction networks is necessary for reliable prediction of reaction mechanism. Though quantum chemical methods provide a desirable accuracy, large computational costs are unavoidable as considering numerous reaction pathways on the networks. We proposed a graph-theoretic approach combined with chemical heuristics (named ACE-Reaction) in previous work [<I>Chem. Sci.</I>2018, 9, 825], which automatically and rapidly finds out the most essential part of reaction networks just from reactants and products, and here we extended it by incorporating a stochastic approach for microkinetic modeling. To show its performance and broad applicability, we applied it to 26 organic reactions, which include 16 common functional groups. As a result, we could demonstrate that ACE-Reaction successfully found the accepted mechanism of all reactions, most within a few hours on a single workstation, and additional microkinetic modeling automatically discovered new competitive paths as well as a major path.</P> [FIG OMISSION]</BR>
Synthesis of Substituted Oxazoles by Visible-Light Photocatalysis
Chatterjee, Tanmay,Cho, Ji Young,Cho, Eun Jin American Chemical Society etc. 2016 Journal of organic chemistry Vol.81 No.16
<P>A simple and practical method for the synthesis of substituted oxazoles has been developed using readily available alpha-bromoketones and benzylamines by visible-light photocatalysis at room temperature. The process, which requires 1 mol % of [Ru(bpy)(3)]Cl-2 photocatalyst with K3PO4 and CCl3Br, is effective for accessing a variety of valuable oxazole compounds. The synthetic utility of our protocol was also demonstrated by preparing a natural prochict, texaline.</P>