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61.
Bin Du Adam Langlois Daniel Fortin Christine Stern Pierre D. Harvey 《Journal of Cluster Science》2012,23(3):737-751
The title cluster is luminescent at 77?K and exhibits an unsaturated site for binding anions when the counter ion is PF6 ?. A series of five non-luminescent metalloporphyrins exhibiting carboxylate anchoring groups were synthesized and characterized. These are the sodium salts of the 5-carboxyphenyl-tri-10,15,20-tolyl-, trans-di-5,10-carboxyphenyl-di-15,20-tolyl-, and tetra-5,10,15,20-carboxyphenyl(metallo)porphyrin (metallo?=?chloroiron(III), nickel(II)) anions. Evidence for supramolecular assemblies between the carboxylates and the cluster is provided by 31P NMR and UV?Cvis spectroscopy. The binding constant, K1n, extracted from the UV?Cvis data via Benesi-Hildebrand, Scott and Scatchard plots are approximately 21,000?±?5,000?M?1 for the nickel(II) species, in agreement with the previously reported zinc(II) ones (K11?=?20,000?±?2,000?M?1), but those for the chloroiron(III) are measured to be lower (12,500?±?3,500?M?1). This association is accompanied by a complete quenching of the luminescence of the cluster which can only be due to an efficient energy transfer to the d?Cd states of the chloroiron(III) and nickel(II) species but an electron transfer from the nickel(II)-containing chromophore to the cluster is also possible. This work demonstrates the profound effect that supramolecular interactions may have on the photophysical properties despite the long donor?Cacceptor separation. 相似文献
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Harvey Dubner. 《Mathematics of Computation》2002,71(238):833-835
The Repunit R is a probable prime. In order to prove primality R49080 must be approximately 33.3% factored. The status of this factorization is included.
65.
Treatment of molybdenum Fischer carbene complexes with 6-methylene-7-octen-1-yne derivatives at 40 degrees C generates substituted tricyclo[4.3.1.0(1,6)]deca-2,4-dienes in good yield. Pentacarbonyl(butylmethoxycarbene)molybdenum(0) afforded the highest cyclization yields (54%), while the analogous chromium carbene complex gave no reaction. The range of dienyne substrates that participate in this reaction is explored and its mechanism is analyzed and discussed. 相似文献
66.
The unit -planes on which the first Pontryagin form of the Grassmann manifolds achieves its maximum are determined. This is a shorter and unified proof of results first obtained in 1995 by H. Gluck et al. and in 1998 by W. Gu.
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M.A.H. Smith G.A. Harvey G.L. Pellett A. Goldman D.J. Richardson 《Journal of Molecular Spectroscopy》1984,105(1):105-112
N2-broadened halfwidths have been measured for 51 absorption lines belonging to the ν3 fundamental band of hydrogen cyanide (1H12C14N) near 3311 cm?1. The data were recorded at room temperature using a Fourier transform spectrometer with a nominal resolution of 0.06 cm?1. A nonlinear least-squares spectral-fitting procedure was used to obtain both line intensities and collision-broadened halfwidths from scans recorded at several different pressures. The N2-broadened halfwidths, determined for all lines with J ≤ 25 in both the P and R branches of the band, show the expected distribution with J for broadening by a nonpolar gas. The halfwidth values range from approximately 0.17 cm?1 atm?1 near the band center to 0.11 cm?1 atm?1 for high-J lines. The band intensity for the ν3 fundamental derived from these measurements is 236.2 ± 9.5 cm?2 atm?1 at 296 K, and empirical coefficients for the vibration-rotation interaction F-factor were also determined. 相似文献
68.
Random walks on lattices. IV. Continuous-time walks and influence of absorbing boundaries 总被引:1,自引:0,他引:1
The general study of random walks on a lattice is developed further with emphasis on continuous-time walks with an asymmetric bias. Continuous time walks are characterized by random pauses between jumps, with a common pausing time distribution(t). An analytic solution in the form of an inverse Laplace transform for P(l, t), the probability of a walker being atl at timet if it started atl
o att=0, is obtained in the presence of completely absorbing boundaries. Numerical results for P(l, t) are presented for characteristically different (t), including one which leads to a non-Gaussian behavior for P(l, t) even for larget. Asymptotic results are obtained for the number of surviving walkers and the mean l showing the effect of the absorption at the boundary.This study was partially supported by ARPA and monitored by ONR(N00014-17-0308). 相似文献
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