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101.
102.
The "flexible" 3 and "rigid" cyclic viologens 4, diquarternary salts of 2,2'-bipyridine and 1,10-phenanthroline, respectively, were treated with tributylphosphine (1) in acetonitrile containing a large amount of methanol under an argon atmosphere. A single electron transfer (SET) easily occurred from the latter to the former, the SET to 4 being 10(5)-10(6) times faster than the SET to 3. The reorganization energy lambda for the latter SET is thought to be larger than that for the former SET, because 3 undergoes a structural change upon the one-electron reduction to its radical cation, whereas the one-electron reduction of 4 takes place without a structural change. Taking into account the difference in lambda, and also taking into account the bond formation energy brought about by the follow-up reaction of the phosphine radical cation 1*(+) with methanol, the observed kinetics were well interpreted in terms of the Marcus theory. 相似文献
103.
104.
A marked acceleration property for the Diels-Alder reaction was observed in an aqueous micellar system composed of perfluorohexane and lithium perfluorooctanesulfonate. The reaction rate increased with the concentration of the equimolar mixture of PFH and LiFOS, and the rate in 500 mM PFH and 500 mM LiFOS was about 100-fold greater than that in water without the fluorous field. After completion of the reaction, the products were simply extracted from the aqueous reaction mixture using n-hexane. [reaction: see text]. 相似文献
105.
Zhaoma Shu Iku Tanaka Azumi Ota Daichi Fushihara Naoko Abe Saki Kawaguchi Kosuke Nakamoto Fumiaki Tomoike Seiichi Tada Yoshihiro Ito Yasuaki Kimura Hiroshi Abe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(20):6683-6687
Development of intracellular delivery methods for antisense DNA and siRNA is important. Previously reported methods using liposomes or receptor‐ligands take several hours or more to deliver oligonucleotides to the cytoplasm due to their retention in endosomes. Oligonucleotides modified with low molecular weight disulfide units at a terminus reach the cytoplasm 10 minutes after administration to cultured cells. This rapid cytoplasmic internalization of disulfide‐modified oligonucleotides suggests the existence of an uptake pathway other than endocytosis. Mechanistic analysis revealed that the modified oligonucleotides are efficiently internalized into the cytoplasm through disulfide exchange reactions with the thiol groups on the cellular surface. This approach solves several critical problems with the currently available methods for enhancing cellular uptake of oligonucleotides and may be an effective approach in the medicinal application of antisense DNA and siRNA. 相似文献
106.
Shogo Morisako Seiya Watanabe Satoru Ikemoto Satoshi Muratsugu Mizuki Tada Makoto Yamashita 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15173-15177
A pincer‐iridium complex bearing a Lewis‐base‐free X‐type alumanyl ligand has been synthesized. X‐ray diffraction, NMR and IR spectroscopy, as well as XANES analysis confirmed its tetrahydrido‐IrV structure and Lewis acidity at the Al center as supported by DFT calculations. The resulting complex was applied as a catalyst for the transfer dehydrogenation of cyclooctane. 相似文献
107.
Atsunobu Akita Emeritus Prof. Hisayoshi Kobayashi Prof. Dr. Hiroaki Tada 《Chemphyschem》2019,20(16):2054-2059
The development of nanostructured semiconductor electrodes represented by a mesoporous TiO2 nanocrystalline (mp-TiO2) film is currently bringing great progresses in photoelectrochemical (PEC) devices for solar-to-electricity and solar-to-chemical conversion. Two serious losses can occur in PEC devices: 1) recombination between the conduction band (CB) electrons and valence band (VB) holes in the bulk and at the surface and 2) back reaction or electron trapping by oxidant in the electrolyte solution during transport to the electron-collecting electrode. Thus, the major challenge in common with the nanostructured semiconductor photoanodes is to achieve efficient charge separation and electron transport. In this study, an ultrathin SiOx layer was formed on both the external and the internal surface of mp-TiO2 using an original chemisorption-calcination technique employing 1,3,5,7-tetramethyltetrasiloxane as a starting material. The SiOx surface modification of the mp-TiO2 photoanode drastically prolongs the mean lifetime of CB-electrons in TiO2 because of enhanced charge separation and electron transport by the negative charge applied in aqueous electrolyte solution. We have demonstrated that the performance of a one-compartment H2O2-photofuel cell using mp-TiO2 as the photoanode is greatly boosted by the surface modification with the SiOx layer. We anticipate that this methodology is widely applicable to nanostructured metal oxide semiconductor electrodes, contributing to the improvement in the performance of PEC devices. 相似文献
108.
The reactions of TbtPPTbt (Tbt = 2,4,6‐tris[bis(trimethylsilyl)methyl]phenyl) with elemental sulfur and selenium in the presence of triethylamine resulted in the formation of the corresponding thia‐ and selenadiphosphiranes in 71% and 65%, respectively, whereas the tellurization reaction was unsuccessful probably due to the steric reason. On the other hand, treatment of TbtPPFc (Fc = ferrocenyl) with elemental sulfur, selenium, and tributylphosphine telluride afforded the corresponding thia‐, selena‐, and telluradiphosphiranes in 84%, 88%, and 66% yields, respectively. The molecular structures of these three‐membered heterocyclic compounds were confirmed by spectroscopic analysis. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:443–449, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20449 相似文献
109.
ABSTRACTThe objective of this study was to determine whether sodium caseinate can inhibit the aggregation of whey protein induced by pressure treatment. Solutions of β-lactoglobulin (β-Lg, 0.2%, w/v) and mixtures containing 0.2% (w/v) β-Lg and 0–0.5% (w/v) sodium caseinate (NaCas) were pressurized at 400–800?MPa. NaCas suppressed the aggregation of β-Lg induced by pressure treatment, and this function was dependent on the concentration of NaCas. Furthermore, NaCas altered the aggregation process of β-Lg by suppressing the transition of the aggregate from the soluble phase to the insoluble phase and, as a result, the fraction of insoluble aggregates was decreased. During this process, NaCas formed stable complexes with the denatured β-Lg, and the formation of complexes prevented further aggregation of β-Lg. These results indicate that NaCas exhibits a chaperone-like activity under high pressure. 相似文献
110.