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61.
Salvador Puig-Torres Gary E. Martin Joseph J. Ford M. Robert Willcott Keith Smith 《Journal of heterocyclic chemistry》1982,19(6):1441-1446
The reaction of the dianion of 3-mercaptopyridin-2(1H)-thione with 2-chloronitrobenzene in N,N-dimethylformamide leads to the formation of 1-azathianthrene, the first reported mono-aza analog of the thianthrene ring system. A partial assignment of the 13C-nmr spectrum of the title compound is reported, the assignment based on chemical shift arguments, spin-lattice (T1) relaxation times and 1H-13C spin coupling constants. Amplitude modulated two-dimensional Fourier transform (AM2DFT) techniques were employed for the acquisition of the heteronuclear spin-coupling constants. 相似文献
62.
A dimethylsiloxane diluted polysiloxane side chain co-polymer with non-chiral banana-shaped mesogenic units shows an optically isotropic ferroelectric switching polar smectic C phase (SmCPF) consisting of a conglomerate of homogeneously chiral domains with opposite handedness. 相似文献
63.
Matthew S. Johnson Keith T. Kuwata Chi-Kin Wong Mitchio Okumura 《Chemical physics letters》1996,260(5-6):551-557
The infrared spectrum of the ionic cluster I−(H2O) was recorded from 3170 to 3800 cm−1 by vibrational predissociation spectroscopy. A strong multiplet observed at 3415 cm−1 and a narrow band at 3710 cm−1 were assigned as a hydrogen-bonded OH stretch and free OH stretch respectively, indicating that H2O forms a single hydrogen bond with the iodide anion. Ab initio vibrational frequencies and intensities were computed at the second-order Møller-Plesset (MP2) level for the minimum energy configuration, a nearly linear hydrogen-bonded isomer, and for a low-lying saddlepoint, a symmetric C2v bridged isomer. The spectrum predicted for the hydrogen-bonded isomer agreed well with experiment. 相似文献
64.
65.
Daixin Tong Keith D. Bartle Anthony A. Clifford Robert E. Robinson 《Journal of separation science》1992,15(8):505-509
A unified approach to sequential gas and supercritical fluid Chromatography using 50 μm i.d. open tubular columns is described. Sample introduction is performed by means of a rotary injection valve. In order that linear velocities can be optimized independently, a second rotary valve in the chromatographic oven is used to direct the flow of column eluate to the flame ionization detector through either fused silica tubing in GC, or a frit restrictor in SFC. Applications of sequential GC-SFC on a 50 μm i.d. open tubular column are demonstrated, and comparisons made between sequential GC-SFC on 50 and 100 μm i.d. columns. 相似文献
66.
Hill RT Lyon JL Allen R Stevenson KJ Shear JB 《Journal of the American Chemical Society》2005,127(30):10707-10711
The functionality and structural diversity of biological macromolecules has motivated efforts to exploit proteins and DNA as templates for synthesis of electronic architectures. Although such materials offer promise for numerous applications in the fabrication of cellular interfaces, biosensors, and nanoelectronics, identification of techniques for positioning and ordering bioelectronic components into useful patterns capable of sophisticated function has presented a major challenge. Here, we describe the fabrication of electronic materials using biomolecular scaffolds that can be constructed with precisely defined topographies. In this approach, a tightly focused pulsed laser beam capable of promoting protein photo-cross-linking in specified femtoliter volume elements is scanned within a protein solution, creating biomolecular matrices that either remain in integral contact with a support surface or extend as free-standing structures through solution, tethered at their ends. Once fabricated, specific protein scaffolds can be selectively metallized via targeted deposition and growth of metal nanoparticles, yielding high-conductivity bioelectronic materials. This aqueous fabrication strategy opens new opportunities for creating electronic materials in chemically sensitive environments and may offer a general approach for creating microscopically defined inorganic landscapes. 相似文献
67.
Jörg Senn-Bilfinger John R. Ferguson Keith W. Lumbard Karl Zech Peter J. Zimmermann 《Tetrahedron letters》2006,47(19):3321-3323
Glucuronide conjugates of Soraprazan (BY359), a potent novel anti-secretory drug (currently in Phase II clinical trials), were not directly accessible synthetically. This was due to the relative instability of Soraprazan under the harsh Lewis acid conditions employed in popular glucuronidation methodologies and a lack of reactivity under alternative, Koenigs-Knorr, coupling conditions. We have now devised a successful synthesis using the novel N-acetylated Soraprazan to access the required glucuronide metabolites on gram scale. Coupling of this novel aglycone with methyl 1-O-trichloroacetimidoyl-2,3,5-tri-O-isobutyryl-α-d-glucopyran-uronate in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) gave the protected glucuronide intermediates. A one-pot two-step deprotection involving hydrolysis of the ester functionalities and removal of the N-acetyl group with alkaline hydrazine delivered the title compounds in satisfactory yield. 相似文献
68.
Shigeru?ArimotoEmail author Mark?Spivakovsky Keith?F.?Taylor Paul?G.?Mezey 《Journal of mathematical chemistry》2005,37(2):171-189
The present article is a direct continuation of the first part of this series. We reduce a proof of the Fukui conjecture (concerning the additivity problem of the zero-point vibrational energies of hydrocarbons) to that of a proposition related to the theory of algebraic curves, so that we can focus on the key mechanism of the additivity phenomena. Namely, by establishing what is called the Basic Piecewise Monotone Theorem (BPMT), we reduce a proof of the Fukui conjecture to that of a proposition, called the Local Analyticity Proposition, Version 1 (LAP1), which admits a proof via resolution of singularities. By LAP1, the essential part of the mechanism of the asymptotic linearity phenomena is extracted and is elucidated by using tools from the mathematical theory of algebraic curves, whose language is of vital importance in analyzing the crux of the additivity mechanism.
Dedicated to the memory of Prof. Kenichi Fukui (1918–1998). 相似文献
69.
Ibrahim Y Alsharaeh E Dias K Meot-Ner Mautner M El-Shall MS 《Journal of the American Chemical Society》2004,126(40):12766-12767
We studied the stepwise hydration and solvent-mediated deprotonation of the benzene*+ cation (Bz*+) and found several unusual features. The solvent binding energies DeltaH on-1,n for the reactions Bz*+(H2O)n-1 + H2O --> Bz*+(H2O)n are nearly constant at 9 +/- 1 kcal mol-1 for n = 1 to 8. We observed a remarkable sudden decrease in the entropy of association accompanying the formation of Bz*+(H2O)7 and Bz*+(H2O)8, indicating strong orientational restraint in the hydration shells of these clusters consistent with the formation of cagelike structures. We observed the size-dependent deprotonation of Bz*+ in a cooperative multibody process, where n H2O molecules (n >/= 4) can remove a proton from Bz*+ to form protonated water clusters. We measured, for the first time, the temperature dependence of such a process and found a negative temperature coefficient of a magnitude unprecedented in any chemical reaction, of the form k = AT-67+/- 4, or in an Arrhenius form having an activation energy of -34 +/- 1 kcal mol-1. The temperature effect may be explained by Bz*+ and four H2O molecules needing to be assembled from gas-phase components to form the reactive species. Such large temperature effects may be therefore general in solvent cluster-mediated reactions. 相似文献
70.
Modifications of the SCF-LCAO-π-MO method analysed in the previous paper are described in which provision is made for the incorporation of Variable Bond Order and Variable Electronegativity procedures. A comparison is made with the results of other π-electron calculations and values are reported for twenty hydrocarbon systems. 相似文献