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141.
Ohulchanskyy TY Pudavar HE Yarmoluk SM Yashchuk VM Bergey EJ Prasad PN 《Photochemistry and photobiology》2003,77(2):138-145
Monomethine cyanine dye 4-((1-methylbenzothiazolyliliden-2)methyl)-1,2,6-trimethylpyridinium perchlorate (Cyan 40) was investigated as a two-photon-excited fluorescence probe for nucleic acids (NA). Cyan 40 has been shown to demonstrate efficient two-photon-excited fluorescence in the presence of NA in vitro in contrast to solutions without NA. Two-photon confocal laser scanning microscopy (TPCLSM) and two-photon laser scanning microspectrofluorometry were used to check the possibility of using Cyan 40 as two-photon-excited fluorescence label for NA in living cells. Study of dye effect on viability of cells was also carried out. We ascertained that Cyan 40 is a cell-permeant dye, manifesting efficient two-photon-excited fluorescence when bound to NA in living cells, without any significant influence on viability of cells. TPCLSM images obtained from stained cells indicate preferential RNA staining by Cyan 40 compared with DNA. 相似文献
142.
József Rábai Dénes SzabóEszter K Borbás István KövesiIstván Kövesdi Antal CsámpaiÁgnes Gömöry Valeriy E PashinnikYuriy G Shermolovich 《Journal of fluorine chemistry》2002,114(2):199-207
The evolution of the term fluorous is addressed first, then a concise terminology is proposed, including fluorous partition coefficient, specific fluorophilicity and fluorousness. Some examples are shown for the design of higher generation fluorophilic molecules, involving Class I to Class III ponytails. Fluorophilic ethers of the structure of ArC(CF3)2O(CH2)m(CF2)nF (m=1, n=1, 7; m=3, n=8) are obtained in high yields, when 2-aryl-1,1,1,3,3,3-hexafluoro-propanols are reacted either with trifluoroethyl- and 1H,1H-perfluorooctyl triflates (NaH/DMF, Williamson ether synthesis) or with 3-perfluorooctyl-propanol (Ph3P/EtO2CNNCO2Et/PhCF3, Mitsunobu reaction), respectively. Fluorophilic phenol- and perfluoro-tert-butyl ethers can also be prepared effectively by the latter method. In case of higher homologues (n=7, 8) product isolation can be facilitated using fluorous extraction (C6F14/CH3OH). Specific fluorophilicity values of target molecules are estimated using a 2D method and compared with experimentally determined ones. 相似文献
143.
The crystal structure of the Aurivillius phase Bi5TiNbWO15 has been analyzed in detail using powder X-ray and neutron diffraction. The structure can be described as a regular intergrowth of alternating single and double perovskite-like layers sandwiched between fluorite-like bismuth oxide layers, such that the layer sequence is … [WO4]-[Bi2O2]-[BiTiNbO7]-[Bi2O2] …. There is complete ordering of tungsten within the B sites of the single perovskite layer, so that the structure can be described as a direct intergrowth of the ‘component’ Aurivillius phases Bi2WO6 and Bi3TiNbO9. At 25 °C the structure adopts the polar orthorhombic space group I2cm, , , . 相似文献
144.
The electron transfer (ET) properties of a series of closely related cobalt porphyrins, [2,3,7,8,12,13,17,18-octafluoro-5,10,15,20-tetrakis(pentafluorophenyl)porphyrinato]cobalt, CoF(28)TPP, [2,3,7,8,12,13,17,18-octafluoro-5,10,15,20-tetraphenyl)porphyrinato]cobalt, CoF(8)TPP, 5,10,15,20-tetrakis(pentafluorophenyl)porphyrinato]cobalt, CoF(20)TPP, and [5,10,15,20-tetraphenylporphyrinato]cobalt, CoTPP, were investigated by cyclic voltammetry, cyclic voltammetric digital simulation, in situ UV-vis and IR spectroelectrochemistry, kinetic ET studies, bulk electrolysis, (19)F NMR spectroscopy, X-ray crystallography, and molecular modeling. In benzonitrile containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF(6)) as supporting electrolyte, the ET rate constants for the Co(2+/3+) redox couples were found to be strongly substituent dependent; the heterogeneous ET rate constant (k(el)) varied by a factor of 10(4), and the ET self-exchange rate constants (k(ex)) varied over 7 orders of magnitude for the compounds studied. The remaining observed ring oxidation and metal and ring reduction events exhibited nearly identical k(el) values for all compounds. UV-vis and IR spectroelectrochemistry, bulk electrolysis, and (19)F NMR spectroscopic studies support attribution of different ET rates to widely varying inner sphere reorganization energies (lambda(i)) for these closely related compounds. Structural and semiempirical (PM3) studies indicate that the divergent kinetic behavior of CoTPP, CoF(8)TPP, CoF(20)TPP, and CoF(28)TPP first oxidations arises mainly from large nuclear reorganization energies primarily associated with core contraction and dilation. Taken together, these studies provide rational design principles for modulating ET rate constants in cobalt porphyrins over an even larger range and provide strategies for similar manipulation of ET rates in other porphyrin-based systems: substituents that lower C-C, C-N, and N-M vibrational frequencies or minimize porphyrin orbital overlap with the metal-centered orbital undergoing a change in electron population will increase k(ET). The heme ruffling apparent in electron transfer proteins such as cytochrome c is interpreted as nature's exploitation of this design strategy. 相似文献
145.
V. N. Bezmelnitsyn A. A. Vasiliev B. B. Chaivanov 《Reaction Kinetics and Catalysis Letters》1984,25(1-2):93
The probabilities of the decay of atomic fluorine on solid xenon and xenon difluoride at 77 K have been determined.
77 .相似文献
146.
Khlyustova Anna V. Sirotkin Nikolay A. Kraev Anton S. Titov Valeriy A. Agafonov Alexander V. 《Plasma Chemistry and Plasma Processing》2021,41(2):643-657
Plasma Chemistry and Plasma Processing - Two types of plasma in contact with water were employed for the synthesis of mixed-phase TiO2 in a liquid. This is glow discharge with a metal cathode and... 相似文献
147.
Dr. Zhenghai Yang Dr. Srinivas Doddipatla Prof. Dr. Ralf I. Kaiser Vladislav S. Krasnoukhov Prof. Dr. Valeriy N. Azyazov Prof. Dr. Alexander M. Mebel 《Chemphyschem》2021,22(2):184-191
The previously unknown silylgermylidyne radical (H3SiGe; X2A′′) was prepared via the bimolecular gas phase reaction of ground state silylidyne radicals (SiH; X2Π) with germane (GeH4; X1A1) under single collision conditions in crossed molecular beams experiments. This reaction begins with the formation of a van der Waals complex followed by insertion of silylidyne into a germanium-hydrogen bond forming the germylsilyl radical (H3GeSiH2). A hydrogen migration isomerizes this intermediate to the silylgermyl radical (H2GeSiH3), which undergoes a hydrogen shift to an exotic, hydrogen-bridged germylidynesilane intermediate (H3Si(μ-H)GeH); this species emits molecular hydrogen forming the silylgermylidyne radical (H3SiGe). Our study offers a remarkable glance at the complex reaction dynamics and inherent isomerization processes of the silicon-germanium system, which are quite distinct from those of the isovalent hydrocarbon system (ethyl radical; C2H5) eventually affording detailed insights into an exotic chemistry and intriguing chemical bonding of silicon-germanium species at the microscopic level exploiting crossed molecular beams. 相似文献
148.
Valeriy E. Pashinnik Alexei V. Borovikov Yuriy G. Shermolovich 《Heteroatom Chemistry》2008,19(1):66-71
The path of the reaction of aryl‐N‐(p‐toluenesulfonyl)‐sulfinimidoyl fluorides and triphenylphosphine is highly dependent on the order of the reactants addition. Addition of triphenylphos‐phine to aryl‐N‐(p‐toluenesulfonyl)‐sulfinimidoyl fluorides results in the formation of triphenyl(aryl‐thio)phosphonium salts of N,N′‐bis(p‐toluenesul‐fonyl)aryl‐sulfinamidines and triphenyldifluorophosphorane. By changing the reagent addition order, we obtained triphenyldifluorophosphorane, P,P,P‐triphenyl‐N‐(p‐toluenesulfonyl)‐phosphine imide, and diaryl disulfides. The outcome of the reaction aryl‐N‐(arenesulfonyl)‐sulfinimidoyl chlorides and triphenylphosphine does not depend on the order of addition of the reactants. P,P,P‐Triphenyl‐N‐(arenesulfonyl)‐phosphine imides, triphenyldichloro‐phosphorane, and diaryl disulfides were formed as a result. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:66–71, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20408 相似文献
149.
We explicitly compute limit shapes for several grand canonical Gibbs ensembles of partitions of integers. These ensembles appear in models of aggregation and are also related to invariant measures of zero range and coagulation-fragmentation processes. We show, that all possible limit shapes for these ensembles fall into several distinct classes determined by the asymptotics of the internal energies of aggregates. 相似文献
150.
Kamlesh Kumar Valeriy Luchnikov Volodymyr Senkovskyy 《European Polymer Journal》2008,44(12):4115-4121
This paper describes an experimental study of the polymer microtube formation in different fabrication conditions. A photolithography route is demonstrated for the fabrication of large amount of uniform and good quality polymer microtubes. TEM grids were used as mask and exposure of UV radiation was done in two steps to create asymmetric patterns. The diameter of tube was controlled by regulating the thickness of polymer layers, UV radiation dose and concentration of acidic solution. The results indicate that thickness of the bilayer film was the most dominating factor to determine the tube’s dimension, and diameter of the tubes increased with increase in the thickness of bilayer. The kinetics of the tube formation was studied with respect to acidity of the solution and UV dose. Rate of rolling increased with the acidity of the solution. Tube diameter and rate of rolling decreased with the increase of the UV exposure time. Films with two-dimensional gradients of layer thicknesses were prepared to study a broad range of parameters in a single experiment. The tubes were characterized in detail using optical microscopy and scanning electron microscopy. These polymer microtubes have potential applications in microfluidic devices and biotechnology field. 相似文献