排序方式: 共有27条查询结果,搜索用时 15 毫秒
21.
Tanguy Jousselin‐Oba Parker E. Deal Aaron G. Fix Conerd K. Frederickson Chris L. Vonnegut Abderrahim Yassar Lev N. Zakharov Michel Frigoli Michael M. Haley 《化学:亚洲杂志》2019,14(10):1737-1744
A set of fully‐conjugated indenofluorenes has been synthesized and confirmed by solid‐state structure analysis. The indeno[2,1‐c]fluorenes and their benzo‐fused analogues all contain the antiaromatic as‐indacene core. The molecules possess high electron affinities and show a broad absorption that reaches into the near‐IR region of the electromagnetic spectrum. All of the featured compounds reversibly accept up to two electrons as revealed by cyclic voltammetry. Analysis of molecule tropicity using NICS‐XY scan calculations shows that, while the as‐indacene core is less paratropic than s‐indacene, benz[a]‐annulation further reduces the antiaromaticity of the core. Antiaromatic strength of the as‐indacene core can also be tuned by the position of fusion of additional arenes on the outer rings. 相似文献
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Walter J. Deal 《Theoretical chemistry accounts》1990,77(4):225-237
Ann-dimensional system with a classical HamiltonianH(p, q, t) may be described by a phase-space distribution function D(q, p, t). The dynamical equation for D(q, p, t) is postulated to be
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H. Christopher Fry Cynthia Deal Erin Barr Scott D. Cummings 《Journal of photochemistry and photobiology. A, Chemistry》2002,150(1-3):37-40
Photolysis of dimethylsulfoxide (dmso) solutions of the compound Pt(en)Cl2, where en=ethylene-1,2-diamine, leads to solvolysis of the complex and formation of Pt(en)(dmso)Cl+. The reaction follows clean pseudo-first-order kinetics with parallel photolytically activated and thermally activated paths. Both paths are first-order in both Pt(en)Cl2 and solvent. Eyring analysis of the rate constants for 25 °C≤T≤55 °C yielded a Gibbs energy of activation of 96 kJ mol−1 for the thermal pathway and no measurable activation barrier for the photochemical pathway. The quantum yield for the photochemical path is 0.22, as determined using ferrioxalate actinometry. 相似文献
25.
Correlation between the motion of a highly excited outer electron and that of the remaining ionic “core” of an atom is generally treated in an adiabatic approximation, in which it is assumed that the outer electron affects the core in the same way as a stationary point charge. An alternative approach to this correlation problem which avoids the adiabatic approximation is tested here on the 1s2p, 1s3d, and 1s4f states of helium. The results provide the first accurate test of the adiabatic approximation and of a simple correction for the nonzero velocity of the outer electron. The approach used here is based on neglect, in the “correlation” part of the wave function, of the possibility that the outer electron comes closer to the nucleus than any core electron (“penetration”). A correction for this neglect is derived and tested on a version of the adiabatic approximation that likewise neglects penetration. 相似文献
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Deal KA Park G Shao J Chasteen ND Brechbiel MW Planalp RP 《Inorganic chemistry》2001,40(17):4176-4182
Aqueous copper(II) N,N',N' '-trimethyl-cis,cis-1,3,5-triaminocyclohexane (Cu(tach-Me(3))(2+)(aq)) promotes the hydrolysis of activated phosphate diesters in aqueous medium at pH 7.2. This complex is selective for cleavage of the phosphate diester sodium bis(p-nitrophenyl) phosphate (BNPP), the rate of hydrolysis of the monoester disodium p-nitrophenyl phosphate being 1000 times slower. The observed rate acceleration of BNPP hydrolysis is slightly greater than that observed for other Cu(II) complexes, such as [Cu([9]aneN(3))Cl(2)] ([9]aneN(3) identical with 1,4,7-triazacyclononane). The rate of hydrolysis is first-order in phosphate ester at low ester concentration and second-order in [Cu(tach-Me(3))](2+)(aq), suggesting the involvement of two metal complexes in the mechanism of substrate hydrolysis. The reaction exhibits saturation kinetics with respect to BNPP concentration according to a modified Michaelis-Menten mechanism: 2CuL + S <==> LCu-S-CuL --> 2CuL + products (K(M) = 12.3 +/- 1.8 mM(2), k(cat) = (4.0 +/- 0.4) x 10(-)(4) s(-1), 50 degrees C) where CuL (triple bond) [Cu(tach-Me(3))](2+), S (triple bond) BNPP, and LCu-S-CuL is a substrate-bridged dinuclear complex. EPR data indicate that the dicopper complex is formed only in the presence of BNPP; the active LCu-S-CuL intermediate species then slowly decays to products, regenerating monomeric CuL. 相似文献
27.
Thomas J. Deal 《Nuclear Physics A》1973,217(1):210-220
The question of electromagnetic isoscalar dipole transitions is briefly reviewed. An energy weighted sum rule (corrected for c.m. effects) is applied and used with a doorway dominance approximation to predict inelastic form factors. Questions concerning the nature of the excited state are seen to be answerable with the sum rule. 相似文献
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