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Dr. Yan Li Dr. Yuk-Chi Chan Bi-Xiang Leong Dr. Yongxin Li Dr. Emma Richards Indu Purushothaman Dr. Susmita De Dr. Pattiyil Parameswaran Dr. Cheuk-Wai So 《Angewandte Chemie (International ed. in English)》2017,56(26):7573-7578
The trapping of a silicon(I) radical with N-heterocyclic carbenes is described. The reaction of the cyclic (alkyl)(amino) carbene [cAACMe] (cAACMe=:C(CMe2)2(CH2)NAr, Ar=2,6-iPr2C6H3) with H2SiI2 in a 3:1 molar ratio in DME afforded a mixture of the separated ion pair [(cAACMe)2Si:.]+I− ( 1 ), which features a cationic cAAC–silicon(I) radical, and [cAACMe−H]+I−. In addition, the reaction of the NHC–iodosilicon(I) dimer [IAr(I)Si:]2 (IAr=:C{N(Ar)CH}2) with 4 equiv of IMe (:C{N(Me)CMe}2), which proceeded through the formation of a silicon(I) radical intermediate, afforded [(IMe)2SiH]+I− ( 2 ) comprising the first NHC–parent-silyliumylidene cation. Its further reaction with fluorobenzene afforded the CAr−H bond activation product [1-F-2-IMe-C6H4]+I− ( 3 ). The isolation of 2 and 3 confirmed the reaction mechanism for the formation of 1 . Compounds 1 – 3 were analyzed by EPR and NMR spectroscopy, DFT calculations, and X-ray crystallography. 相似文献
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Dongseok Kim Dr. Rosemary L. Calabro Abdullah A. Masud Nadeesha L. Kothalawala Dr. Minsu Gu Dr. Seung-Yeon Kwak Won-Joon Son Dr. Kyu Young Hwang Dr. Hyeonho Choi Prof. Christopher I. Richards Prof. Doo Young Kim Prof. Byeong-Su Kim 《化学:亚洲杂志》2021,16(24):4155-4164
Fluorescent carbon nanodots (CDs) have been highlighted as promising semiconducting materials due to their outstanding chemical and optical properties. However, the intrinsic heterogeneity of CDs has impeded a clear understanding of the mechanisms behind their photophysical properties. In this study, as-prepared CDs are fractionated via chromatography to reduce their structural and chemical heterogeneity and analyzed through ensemble and single-particle spectroscopies. Many single particles reveal fluorescence intensity fluctuations between two or more discrete levels with bi-exponential decays. While the intrinsic τ1 components are uniform among single particles, the τ2 components from molecule-like emissions spans a wider range of lifetimes, reflecting the inhomogeneity of the surface states. Furthermore, it is concluded that the relative population and chemical states of surface functional groups in CDs have a significant impact on emissive states, brightness, blinking, stability, and lifetime distribution of photoluminescence. 相似文献
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G. Jeremy Leong Maxwell C. Schulze Matthew B Strand David Maloney Sarah L. Frisco Huyen N. Dinh Bryan Pivovar Ryan M. Richards 《应用有机金属化学》2014,28(1):1-17
Platinum‐based catalytic materials have received significant attention, particularly in the shape and size control of faceted materials for catalysis. More recently, there has been a rapid increase in the number of reports of successful preparations in this field; however, a fundamental understanding of controlled growth towards catalytic material design is essential for future implementation and broad application. In this review, we provide an overview of the recent findings reported since 2009, focusing on methods for shape control as well as the effects of exposed surface facets on select catalytic reactions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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R. W. Richards 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5):787-815
Small-angle neutron scattering (SANS) studies of polymers are no longer a rarity in polymer science. It is now widely appreciated that SANS can provide unique data which provide greater insight into polymer structural properties than otherwise obtainable. Nonetheless, the costs of the apparatus and special efforts that have to be taken to prepare necessary deuterated polymers mean that such experiments have to be designed with care to ensure that unambiguous data are obtained. There are now in existence several reviews on various aspects [1–4] of SANS studies of polymers; attention in this review is focused on multiphase polymer systems. However, newer aspects of SANS studies on homopolymers will also be discussed, and we begin by a necessarily brief survey of the relevant theoretical expressions. 相似文献
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Enantiopure Ferrocene‐Based Planar‐Chiral Iridacycles: Stereospecific Control of Iridium‐Centred Chirality 下载免费PDF全文
Ross A. Arthurs Dr. Muhammad Ismail Christopher C. Prior Dr. Vasily S. Oganesyan Dr. Peter N. Horton Dr. Simon J. Coles Dr. Christopher J. Richards 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):3065-3072
Reaction of [IrCp*Cl2]2 with ferrocenylimines (Fc=NAr, Ar=Ph, p‐MeOC6H4) results in ferrocene C?H activation and the diastereoselective synthesis of half‐sandwich iridacycles of relative configuration Sp*,RIr*. Extension to (S)‐2‐ferrocenyl‐4‐(1‐methylethyl)oxazoline gave highly diastereoselective control over the new elements of planar chirality and metal‐based pseudo‐tetrahedral chirality, to give both neutral and cationic half‐sandwich iridacycles of absolute configuration Sc,Sp,RIr. Substitution reactions proceed with retention of configuration, with the planar chirality controlling the metal‐centred chirality through an iron–iridium interaction in the coordinatively unsaturated cationic intermediate. 相似文献
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Muhammad Ismail Gennadiy Ilyashenko Christopher J. Richards 《Tetrahedron letters》2009,50(46):6332-2408
A catalysed O/C-carboxyl rearrangement generates the all-carbon stereogenic centre in phenyl 1,3-dimethyl-5-methoxy-2-oxoindoline-3-carboxylate (up to 57% ee). Crystallisation and removal of racemic crystals enhance the ee to 95%. The X-ray crystal structure of the cobalt metallocene-pyrrolidinopyridine nucleophilic catalyst employed is reported. 相似文献