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61.
Tachi Y Aita K Teramae S Tani F Naruta Y Fukuzumi S Itoh S 《Inorganic chemistry》2004,43(15):4558-4560
A dicopper(I) complex supported by a novel asymmetric pentapyridine dinucleating ligand, consisting of tetradentate and tridentate metal-binding sites, has been synthesized and characterized. The dicopper(I) complex reacted with molecular oxygen at a low temperature to give an unprecedented mu-peroxo dicopper(II) complex presumably having a mu-eta1:eta2 binding mode, the spectroscopic features and the reactivity of which have been explored in detail. 相似文献
62.
63.
Kitamura M 《Journal of colloid and interface science》2001,236(2):318-327
The crystallization of calcium carbonate was carried out by mixing CaCl(2) and Na(2)CO(3) solutions. The morphology of precursor formed prior to the nucleation of the polymorphous crystals (calcite and vaterite) varies depending on the feed concentration. The faster nucleation rate of polymorphous crystals in 0.2 mol/L than in 0.05 mol/L solution results in the prompt disappearance of the precursor at 0.2 mol/L. In 0.05 mol/L solutions the lifetime of the precursor is relatively long. The crystallization fraction of vaterite increases with the feed concentration and decreases with the addition rate of Na(2)CO(2) solution. Vaterite takes on the various morphologies of the aggregates of the primary flocculation body (spherulite) depending on the crystallization conditions. Vaterite transforms to calcite by a direct solution-mediated mechanism. During crystallization the concentration attains a stationary value, which increases with the feed concentration and decreases with the addition rate of Na(2)CO(2) solution. This may be due to the crystal size decrease expected from the Gibbs-Kelvin equation. Magnesium ion suppresses the transformation of vaterite by inhibiting the growth of the calcite. Magnesium ion is selectively included in calcite and causes the increase of the attained concentration and the remarkable change in the morphology of calcite especially in 0.05 mol/L solution. Copyright 2001 Academic Press. 相似文献
64.
Secondary carbinamines have been prepared from alkylation of N-boryl imines which were generated in situ from partial reduction of nitriles with sodium brohydride modified by carboxylic acid. 相似文献
65.
Van Truong Do Hiroyuki Hirakata Takayuki Kitamura Van Thanh Vuong Van Lich Le 《International Journal of Solids and Structures》2012,49(13):1676-1684
A novel method combining the experimental data at only two different mixed mode fractures and an empirical interface toughness function has been proposed to establish the interfacial toughness function of a bimaterial in submicron scale. The modified four-point bend specimen was used in experiment to evaluate the first type of mixed mode fracture, while the sandwiched cantilever specimen was employed to get the second one. An empirical interface toughness function reflecting quite accurately the delamination behavior was adopted as a typical one. The obtained results investigated that the proposed method could be used to calibrate not only the interfacial fracture criteria at pure modes but also at any mixed mode fracture of bimaterials in submicron scale. 相似文献
66.
Shoichi Kutsumizu Koushi Morita Tatsuya Ichikawa Shinichi Yano Shuichi Nojima Takanari Yamaguchi 《Liquid crystals》2013,40(11):1447-1458
The structure of the thermotropic cubic phases of 4′- n -alkoxy-3′-nitrobiphenyl-4-carboxylic acids (ANBC- n , where n indicates the number of carbon atoms in the alkoxy group) was studied by X-ray diffraction. For the homologues with n = 15, 16, 17, and 18, the cubic phase was of an Ia 3 d type, whereas the homologues with n = 19, 20, and 21 exhibited an Im 3 m cubic structure; for these seven homologues the same type of cubic structure was observed both on heating and cooling. Further lengthening of the alkoxy chain to n = 22 and 26, however, gave two types of cubic structure in the cubic phase region on heating, one with Im 3 m symmetry in the low temperature region and the other with Ia 3 d symmetry in the high temperature region. On cooling, the two homologues exhibited the Ia 3 d cubic structure only. This is the first example in the cubic phase region of a series of homologues containing two types of structure, dependent on temperature and n . Such a complicated phase diagram in the cubic region is clearly understood qualitatively in terms of Gibbs free energy-temperature diagrams. The dependence of structural parameters such as the cubic lattice constant on the alkoxy chain length n are also presented and discussed. 相似文献
67.
68.
We formed a p?Cn homojunction by implanting nitrogen ions, serving as a p-type dopant, into an n-type ZnO crystal. A forward bias current was injected into the crystal while irradiating it with light, bringing about Joule heating which annealed the crystal and changed the spatial distribution of the N-dopant concentration. This activated the N-dopant, causing its concentration distribution to be modified in a self-organized manner so as to be suitable for generating dressed photons. A light-emitting diode fabricated by this dressed-photon assisted annealing method showed electroluminescence at room temperature. In a device fabricated by annealing under irradiation with 407 nm-wavelength light, at a forward bias current of 20 mA, the peak wavelength of the electroluminescence was 436 nm, the optical output power was 6.2 ??W, and the external quantum efficiency was 1.1×10?4. The emission spectral profile depended on transitions from intermediate phonon states. 相似文献
69.
Surasak Seesukphronrarak Shinichi Kawasaki Shigeki Kuwata Toshikazu Takata 《Journal of polymer science. Part A, Polymer chemistry》2019,57(24):2602-2605
Two novel 9,9‐difunctionalized fluorene‐type monomers, 9,9‐bis(4‐hydroxyphenyl‐ and 4‐aminophenyl)‐2,3:6,7‐dibenzofluorenes, are synthesized by the reaction of dibenzenzofluorenone with phenol and aniline. These monomers are used for the preparation of polyester and polyimide as the typical polymers to evaluate the property change such as thermal stability caused by the benzene rings fused to the fluorene skeleton with keeping good solubility, in comparison with the polymers derived from simple fluorenone. In fact, these two new polymers have the fairly enhanced thermal stability and refractive index value along with satisfactory solubility in organic solvents, enough to emphasize the fusion effect. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2602–2605 相似文献
70.
Ayumi Suzuki Dr. Yuichiro Mutoh Dr. Noriko Tsuchida Chi-Wai Fung Dr. Shoko Kikkawa Prof. Isao Azumaya Prof. Shinichi Saito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3795-3802
Although the chemistry of transition-metal complexes with carbonyl (CO) and thiocarbonyl (CS) ligands has been well developed, their heavier analogues, namely selenocarbonyl (CSe) and tellurocarbonyl (CTe) complexes remain scarce. The limited availability of such CSe and CTe complexes has so far hampered our understanding of the differences between such chalcogenocarbonyl (CE: E=O, S, Se, Te) ligands. Herein, we report the synthesis and properties of a series of cationic half-sandwich ruthenium CE complexes of the type [CpRu(CE)(H2IMes)(CNCH2Ts)][BArF4] (Cp=η5-C5H5−; H2IMes=1,3-dimesitylimidazolin-2-ylidene; ArF=3,5-(CF3)2C6H3). A combination of X-ray diffraction analyses, NMR spectroscopic analyses, and DFT calculations revealed an increasing π-accepting ability of the CE ligands in the order O<S<Se<Te. A variable-temperature NMR analysis of the thus obtained chiral-at-metal CE complexes indicated high stereochemical stability. 相似文献