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971.
Takaaki Yamamoto Jibin Alex Abraham Shigeki Mori Motoki Toganoh Soji Shimizu Masatoshi Ishida Hiroyuki Furuta 《化学:亚洲杂志》2020,15(6):748-752
Incorporating tungsten into the N3 core of a N‐fused porphyrin (NFP; 1 ) affords high‐valent tungsten(VI)‐NFP complexes, WClO2‐1 and 21‐chlorinated WClO2‐3 . The X‐ray structure of WClO2‐1 reveals a distorted octahedral geometry with sitting atop metal coordination. The absorption spectrum of WClO2‐1 displays bathochromically shifted Q‐like bands beyond 1000 nm, indicating an inherently narrow HOMO‐LUMO energy gap. DFT calculations show that the degeneracy of the LUMO and LUMO+1 pair of 1 is significantly resolved by the tungsten(VI) coordination. Conclusively, magnetic circular dichroism (MCD) spectroscopy and cyclic voltammetry provide a rationale for the narrow HOMO‐LUMO energy gap in the “16‐electron” d0 tungsten(VI)‐NFP complexes. 相似文献
972.
Shigeki Kawai Hongqian Sang Lev Kantorovich Keisuke Takahashi Kyoko Nozaki Shingo Ito 《Angewandte Chemie (International ed. in English)》2020,59(27):10842-10847
Recent advances in scanning probe microscopy on surface enable not only direct observation of molecular structures but also local probe reactions, in which unstable short‐lived products have been synthesized and analyzed. Now, an endergonic reaction to synthesize a single Sondheimer–Wong diyne from 6,13‐dibromopentaleno[1,2‐b:4,5‐b′]dinaphthalene by local probe chemistry on a ultra‐thin film of NaCl formed on a Cu(111) surface at 4.3 K is presented. The structures of the precursor, two intermediates, and the final product were directly identified by the differential conductance imaging with a CO functionalized tip. DFT calculations revealed that the multiple‐step reaction, being endergonic overall, is facilitated by temporal charging and discharging of the molecule placed in the nanometric junction between the Cu tip and the Cu substrate underneath the ultra‐thin NaCl film. This local probe reaction expands possibilities to synthesize nanocarbon materials in a bottom‐up manner. 相似文献
973.
Shyamal Kumar Kundu Y. Aoki B. K. Chaudhuri Corresponding author 《Liquid crystals》2013,40(6):787-790
We report the dielectric relaxation behaviour in the antiferroelectric SmCA* and ferrielectric SmCγ* phases of the antiferroelectric liquid crystal 4-[5-(4-octloxyphenyl)-2-pyrimidinyl]phenyl 4,4,4-trifluoro-3-(methoxyphenyl)butanoate which shows an antiferroelectric transition at around 88±0.1°C. In the SmCA* phase, two dielectric relaxation modes have been found, namely the usual antiferroelectric Goldstone mode and another arising from molecular rotation around its short axis. In the SmCγ* phase, one dielectric relaxation mode has been observed due to the ferrielectric Goldstone mode. Dielectric increments and relaxation frequencies of the antiferroelectric and ferrielectric phases are estimated from the fits of the Cole–Cole function of the dielectric spectrum. The dependence of the bias field in the ferrielectric phase is also discussed. 相似文献
974.
Isoshi Nukatsuka Kouta Kodate Ken Iwasaki Hideo Aoki Syo Kasahara Fumihiko Kitagawa 《Journal of Sol-Gel Science and Technology》2013,65(2):230-237
To prepare mesoporous silica thin-films by a simple and environmentally friendly pathway, spontaneous formation of silica thin-films in a sol–gel solution without surfactants was studied. The silica thin-films were prepared by immersing a glass substrate, such as a cylindrical test-tube, into a sol–gel solution containing tetraethoxysilane, water, acetic acid, 2-propanol, and triethylene glycol as a pore-forming agent. The resulting thin-films were transparent. The presence of mesopores was confirmed by field-emission scanning electron microscopy, atomic-force microscopy and nitrogen adsorption–desorption isotherms. The Barrett–Joyner–Halenda plot from the adsorption branch of the isotherms indicated that the pore diameter was 2.6 nm. To illustrate the potential use of the film as an adsorbent, the extraction of polycyclic aromatic hydrocarbons was conducted using the chemically modified silica thin-film coated on a test-tube. The composition of the sol–gel solution was optimized using experimental design, i.e., Doehlert design, and recovery of polycyclic aromatic hydrocarbons. 相似文献
975.
976.
Time-resolved Fourier transform spectroscopy (TR-FTS) is reviewed, with emphasis on synchronous FTS using continuously scanning interferometers. By using a high-resolution Bruker IFS 120 HR, a TR-FTS method has been developed with the help of a microcontroller SX, where a maximum of 64 time-resolved data are recorded with a preset time interval in a single scan of the interferometer. The time resolution is 1 μs, limited by the response time of the detector system used. This method has been applied to a pulsed discharge in an Ar and H2 mixture to observe time profiles of ArH+ and ArH emission spectra. Electronic transitions of He2 have been observed in the infrared region with this method, and from the time profiles, He2 in Rydberg states with higher energy than the b3Π state is found to be produced efficiently in afterglow plasma. Fifteen bands in the 2300-8000 cm−1 region have been assigned by using previously reported data from the optical region. A new band from the 5f state has been assigned for the first time through the 5f-4d band in the 2600 cm−1 region. 相似文献
977.
Yuuichi Orimoto Kazunari Naka Yuriko Aoki 《International journal of quantum chemistry》2005,104(6):911-918
NBO‐based CI/MP through‐space/bond interaction analysis was developed to analyze specific orbital interactions under consideration of the effects of electron correlation. This treatment was applied to the analysis of stereoelectronic effects in SN2 reactions of allyl bromide in which the effects of electron correlation play an important role (ammonia was used as the nucleophilic reagent). The SN2 activation energy in allyl bromide is lower than that in propyl bromide, because both the σ–π* and π–σ* interactions in allyl bromide contribute equally to the stabilization of the transition state. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
978.
Andrej Pevec Alojz Demar Katsuyuki Aoki Iztok Turel 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(11):m545-m547
In the structure of the title compound, {[Rh2(C2H3O2)4(C7H18N2O)]·0.5C4H8O}n or {[Rh2(O2CMe)4(Hbdmap)]·0.5C4H8O}n, where Hbdmap is 1,3‐bis(dimethylamino)propan‐2‐ol, each Hbdmap ligand is coordinated to two [Rh2(O2CMe)4] units by two N atoms, resulting in a polymeric chain structure. The observed coordination mode of the Hbdmap molecule is unprecedented. 相似文献
979.
Visualization is an interdisciplinary imaging technique devoted to make the invisible visible by the techniques of experimental and computer-aided visualizations. It is applicable to various phenomena such as flow, heat, sound, electromagnetism, chemical kinetics and any of their combinations. This review describes the process of development, the present state and fruit of application, and the expectation of future development of visualization using examples. These examples expand to a wide range of fields including engineering, physics, medical science, agriculture, oceanography, meteorology and sports science. 相似文献
980.
A simple and new method has been developed to evaluate the degradation rate of polymer electrolytes caused by the cross-leakage of H2 or O2 in PEFCs. Mixed gas of H2 and air with a constant composition was supplied to a sample powder suspended in water, e.g., consisting of Pt supporting carbon black coated with a perfluorosulfonated acid electrolyte. Fluoride ion released from the electrolyte into the water was quantitatively analyzed as a function of time. The electrolyte was decomposed only when H2, O2, and Pt coexisted. The present method enables to compare the durability of different electrolyte polymers directly under the same controlled environment within a short period. 相似文献