排序方式: 共有56条查询结果,搜索用时 15 毫秒
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Starukh G. N. Smirnova N. P. Eremenko A. M. Chuiko A. A. Abdel-Shafi A. A. Worrall D. R. Wilkinson F. 《Theoretical and Experimental Chemistry》2001,37(2):103-107
We have used fluorescent spectroscopy and laser flash photolysis to investigate the photonics of pyrene molecules in a pyrene–-cyclodextrin inclusion complex in various media. We have observed a protective effect of -cyclodextrin relative to solubilized pyrene molecules during quenching of fluorescence by Ti ions (or titanium dioxide particles) in mixed colloids. In the presence of a precursor of silica (a TEOS solution), the pyrene molecules react with the colloidal silica particles formed, and the reaction is accompanied by decomposition of the pyrene–-cyclodextrin inclusion complex and efficient photoionization of pyrene. 相似文献
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A palladium-catalyzed multicomponent synthesis of imidazolinium carboxylates and imidazolines is described. The palladium catalyst [Pd(CH(R(1))N(R(2))COR(3))Cl](2), or [Pd(allyl)Cl](2), with P(t-Bu)(2)(2-biphenyl) can mediate the simultaneous coupling of two imines, acid chloride, and carbon monoxide into substituted imidazolinium carboxylates within hours under mild conditions (45 °C, 4 atm of CO). The reaction proceeds in good yield with aryl-, heteroaryl-, and alkyl-substituted acid chlorides, as well as variously functionalized imines. Imidazolines are formed via the initial generation of Mu?nchnone intermediates, followed by their cycloaddition with an in situ generated protonated imine. The addition of an amine base can intercept catalysis at Münchnone formation, which allows the subsequent cycloaddition of a second imine. The latter provides a route for the assembly of complex, polysubstituted imidazolinium carboxylates with independent control of all five substituents. The subsequent removal of the nitrogen substituent(s) provides an overall synthesis of imidazolines. 相似文献
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Imprinted diffractive optics for terahertz radiation 总被引:1,自引:0,他引:1
Terahertz diffractive optic elements have been fabricated in polypropylene by imprinting with a silicon master. A silicon master is created with eight phase levels for high diffraction efficiency and etched using inductively coupled plasma reactive ion etching. This technique enables the rapid replication of complex optical structures in a high transmission material. Excellent replication of multilevel high efficiency Fresnel lenses is shown. The resulting lenses were tested with a 2 THz quantum cascade laser. The signal strength at the focus was 70 times the base signal strength. 相似文献
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The complexes Ga2X4 · 2L (L = pyridine, 3-methylpyridine, 4-methylpyridine, morpholine, 1,4-thioxane, 1,4-dithiane, tetrahydropyran, tetrahydrofuran, tetrahydrothiophene and dimethylsulphide) have been prepared. Vibrational spectra indicate that they all contain GaGa bonds and this is confirmed for Ga2Cl4 · 2pyridine by a crystal structure determination which shows it to be isostructural with the bromide analogue. We were unable to synthesize complexes of stoichiometry Ga2X4 · 4L which had previously been reported. 相似文献
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Vancea Anisoara Kirkpatrick Iain Worrall David R. Williams Siân L. 《Research on Chemical Intermediates》2019,45(8):4205-4223
Research on Chemical Intermediates - The energy and electron transfer reactions of anthracene co-adsorbed with an electron donor on silica gel and titania–silica mixed oxides have been... 相似文献
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Gupton JT Telang N Banner EJ Kluball EJ Hall KE Finzel KL Jia X Bates SR Welden RS Giglio BC Eaton JE Barelli PJ Firich LT Stafford JA Coppock MB Worrall EF Kanters RP Keertikar K Osterman R 《Tetrahedron》2010,66(47):9113-9122
Studies directed at the synthesis of (Z)-5-benzylidene-4-arylpyrrol-2(5H)-ones from (Z)-3-aryl-3-haloenoic acids are described. The successful strategy relies on the preparation of (Z)-3-aryl-3-haloenoic acids from acetophenones through the corresponding (Z)-3-aryl-3-haloenals and the conversion of the (Z)-3-aryl-3-haloenoic acids to (Z)-5-benzylidene-4-aryl-5H-furan-2-ones. The furanones were subsequently treated with primary amines and dehydrated to the corresponding (Z)-5-benzylidene-4-arylpyrrol-2(5H)-ones. 相似文献
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Dr. Amanda K. Chaplin Dr. Tadeo Moreno Chicano Bethany V. Hampshire Prof. Dr. Michael T. Wilson Dr. Michael A. Hough Dr. Dimitri A. Svistunenko Dr. Jonathan A. R. Worrall 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(24):6141-6153
Dye decolouring peroxidases (DyPs) are the most recent class of heme peroxidase to be discovered. On reacting with H2O2, DyPs form a high-valent iron(IV)-oxo species and a porphyrin radical (Compound I) followed by stepwise oxidation of an organic substrate. In the absence of substrate, the ferryl species decays to form transient protein-bound radicals on redox active amino acids. Identification of radical sites in DyPs has implications for their oxidative mechanism with substrate. Using a DyP from Streptomyces lividans, referred to as DtpA, which displays low reactivity towards synthetic dyes, activation with H2O2 was explored. A Compound I EPR spectrum was detected, which in the absence of substrate decays to a protein-bound radical EPR signal. Using a newly developed version of the Tyrosyl Radical Spectra Simulation Algorithm, the radical EPR signal was shown to arise from a pristine tyrosyl radical and not a mixed Trp/Tyr radical that has been widely reported in DyP members exhibiting high activity with synthetic dyes. The radical site was identified as Tyr374, with kinetic studies inferring that although Tyr374 is not on the electron-transfer pathway from the dye RB19, its replacement with a Phe does severely compromise activity with other organic substrates. These findings hint at the possibility that alternative electron-transfer pathways for substrate oxidation are operative within the DyP family. In this context, a role for a highly conserved aromatic dyad motif is discussed. 相似文献