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171.
Sun Hwa Lee Li Xu Dr. Byeong Kwon Park Yuri V. Mironov Dr. Soo Hyun Kim Young Ju Song Cheal Kim Prof. Dr. Youngmee Kim Dr. Sung‐Jin Kim Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(15):4678-4685
Two new tetranuclear chalcocyanide cluster complexes, [{Mn(saloph)H2O}4Re4Q4(CN)12]?4 CH3OH? 8 H2O (saloph=N,N′‐o‐phenylenebis(salicylidenaminato), Q=Se ( 1 ‐Se), Te ( 2 ‐Te)), have been synthesized by the diffusion of a methanolic solution of [PPh4]4[Re4Q4(CN)12] into a methanolic solution of [Mn(saloph)]+. The structure of 2 ‐Te has been determined by X‐ray crystallography. These rhenium cluster‐supported [MnIII(saloph)] complexes have been found to efficiently catalyze a wide range of olefin epoxidations under mild experimental conditions in the presence of meta‐chloroperbenzoic acid (mCPBA). Olefin epoxidation by these catalysts is proposed to involve the multiple active oxidants MnV?O, MnIV?O, and MnIII? OOC(O)R. Evidence in support of this interpretation has been derived from reactivity and Hammett studies, H218O‐exchange experiments, and the use of peroxyphenylacetic acid as a mechanistic probe. Moreover, it has been observed that the participation of MnV?O, MnIV?O, and MnIII? OOC(O)R can be controlled by changing the substrate concentration. This mechanism provides the greatest congruity with related oxidation reactions that employ certain Mn complexes as catalysts. 相似文献
172.
173.
This review focuses on synthesis and properties of 1,3-phosphorus-containing zwitterions that have at the anionic center cyano-group and either ester (type one) or carbamate (type two) moieties. Zwitterions belonging to type one possess dual nucleophile reactivity, i.e., depending on the properties of the electrophiles they may form either C- or N-derivatives. Zwitterions belonging to type two possess triple nucleophile reactivity. In their reactions with electrophiles, they may form even three types of derivatives, i.e., at the C-, O- or N-atoms. This nucleophile multiplicity is not just interesting from the theoretical standpoint but may also open the ways to the synthesis of new compounds that can be important from the practical standpoint, such as physiologically active compounds, catalysts, analytical reagents, etc. 相似文献
174.
Yuta Marushima Yuri Uchiumi Kenichi Ogu Akiko Hori 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(8):o406-o409
Two C2‐symmetric meso‐alkynylporphyrins, namely 5,15‐bis[(4‐butyl‐2,3,5,6‐tetrafluorophenyl)ethynyl]‐10,20‐dipropylporphyrin, C50H42F8N4, (I), and 5,15‐bis[(4‐butylphenyl)ethynyl]‐10,20‐dipropylporphyrin, C50H50N4, (II), show remarkable π–π stacking that forms columns of porphyrin centers. The tetrafluorophenylene moieties in (I) show intermolecular interactions with each other through the F atoms, forming one‐dimensional ribbons. No significant π–π interactions are observed in the plane of the phenylene and tetrafluorophenylene moieties in either (I) or (II). The molecules of both compounds lie about inversion centers. 相似文献
175.
In a paper from 1954 Marstrand proved that if K ⊂ ℝ2 is a Borel set with Hausdorff dimension greater than 1, then its one-dimensional projection has positive Lebesgue measure
for almost-all directions. In this article, we give a combinatorial proof of this theorem, extending the techniques developed
in our previous paper [9]. 相似文献
176.
Minovich A Klein AE Janunts N Pertsch T Neshev DN Kivshar YS 《Physical review letters》2011,107(11):116802
We demonstrate experimentally the generation and near-field imaging of nondiffracting surface waves, plasmonic Airy beams, propagating on the surface of a gold metal film. The Airy plasmons are excited by an engineered nanoscale phase grating, and demonstrate significant beam bending over their propagation. We show that the observed Airy plasmons exhibit self-healing properties, suggesting novel applications in plasmonic circuitry and surface optical manipulation. 相似文献
177.
Yuri P. Rybakov Georgi N. Shikin Yuri A. Popov Bijan Saha 《Central European Journal of Physics》2011,9(5):1165-1172
We consider an interacting system of massless scalar and electromagnetic fields, with the Lagrangian explicitly depending
on the electromagnetic potentials, i.e., interaction with broken gauge invariance. The Lagrangian for interaction is chosen
in such a way that the electromagnetic field equation acquires an additional term, which in some cases is proportional to
the vector potential of the electromagnetic field. This equation can be interpreted as the equation of motion of photon with
induced nonzero rest-mass. This system of interacting fields is considered within the scope of Bianchi type-I (BI) cosmological
model. It is shown that, as a result of interaction the isotropization process of the expansion takes place. 相似文献
178.
We studied nonlinear effects in plasmonic metal film waveguides and couplers stimulated by third-order optical response due to ponderomotive metal nonlinearities. We analyzed the structure and dispersion of nonlinear plasmonic guided modes and predicted the bifurcations and symmetry breaking of nonlinear modes for the critical powers, depending on the structure dimensions. 相似文献
179.
I consider two cases where QCD string is described by an effective theory of long strings: the static potential and meson scattering amplitudes in the Regge regime. I show how they can be solved in the mean-field approximation, justified by the large number of space–time dimensions, and argue that it turns out to be exact. I compare contributions from QCD string and perturbative QCD and discuss experimental consequences for the scattering amplitudes. 相似文献
180.