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171.
Previously we reported that fluorescent light (FL) illumination prior to UV irradiation (FL preillumination) had multiple effects on the repair of cyclobutane pyrim-idine dimers (CPD) and (6-4) photoproducts ([6-4] PD) in cultured goldfish cells (RBCF-1) at the exponentially growing phase. In this study, it is shown that even under the confluent condition of RBCF-1 cells, FL preillumination increased the disappearance of (6-4) PD in the dark. In addition, both at confluence and at the exponentially growing phase, the disappearance of (6-4) PD after PR treatment was increased by FL preillumination to RBCF-1 cells. Moreover, it was found that H2O2 pre-treatment, followed by UV irradiation, of the exponentially growing cells also enhanced the disappearance of (6-4) PD in the dark and by photorepair treatment. The degree of enhancement by H2O2 pretreatment was almost the same as that by FL preillumination. 相似文献
172.
Toshiaki Morimoto Nobuhiro Obara Iku Yoshida Kiyoshi Tanaka Toshiyuki Kan 《Tetrahedron letters》2007,48(17):3093-3095
New axially chiral P,O,N-type ligands bearing both a diphenylphosphino group and 2-(dialkylamino)ethyloxy (or 2-pyridylmethyloxy) groups were designed and prepared along with P,O,O-type ligands by employing an easily available chiral component, (R)-2-hydroxy-2′-diphenylphosphinyl-1,1′-binaphthyl. Among the ligands the simplest P,O,N-type one bearing a 2-(dimethylamino)ethyloxy group was found to be the most efficient in copper-catalyzed enantioselective conjugate addition of diethylzinc to a cyclic enone, 2-cyclohexen-1-one, providing high enantioselectivity up to 99% ee. 相似文献
173.
Tokuyuki Kuroda Koji Hisamura Nobuhiro Nakamizo Yoshio Otsuji 《Journal of heterocyclic chemistry》1992,29(5):1143-1147
2′-Deoxy-5-fluorouridine (5-FUdR) derivatives having various types of sulfur-containing substituents at the 5′-O-position were synthesized and their γ-radiolyses were studied in aqueous solutions. The γ-radiolysis of compounds having 1,3-dithiol-2-yl and 1,3-dithian-2-yl substituents at the 5′-O-position efficiently gave 5-FUdR, specifically via the attack of hydroxyl radical. On the other hand, the γ-radiolysis of a compound having a sulfonylmethyl substituent at the 5′-O-position gave less efficiently 5-FUdR, specifically via the attack of the hydrated electron. The mechanistic features of these reactions are discussed. 相似文献
174.
Nobuhiro Anzai Hiroko Kurihara Masato Sone Hidemitsu Furukawa Toshiyuki Watanabe Kazuyuki Horie Sandeep Kumar 《Liquid crystals》2006,33(6):671-679
We have found that the discotic nematic liquid crystal, hexakis(4-nonylphenylethynyl)benzene (HNEB), doped with the racemic chromium complex Cr(Ocacac)3, shows a novel straight-needle texture with hexagonal columnar alignments, changing to a curved-needle texture under irradiation of circularly polarized light (CPL). This novel phenomenon is specific to the mixture of HNEB and Cr(Ocacac)3. The formation of curved needles means that chiroselective photoinversion of racemic Cr(Ocacac)3 by CPL irradiation induces a needle direction change in a discotic liquid crystal. The change in chirality of Cr(Ocacac)3 in HNEB induced by CPL irradiation, and the resulting nano-segregation of its enantiomers during cooling from the isotropic to mesophase of HNEB, are considered to influence changes in the alignment of columns and/or small domains of column aggregates in the discotic liquid crystal. 相似文献
175.
Structures of LiCaAlF6 and LiSrAlF6 at 120 and 300 K by synchrotron X-ray single-crystal diffraction
Satoru Kuze Nobuo Ishizawa Nobuhiro Kodama Brian Henderson 《Journal of solid state chemistry》2004,177(10):3505-3513
The low-temperature structures of the colquiriite-type fluorides LiCaAlF6 and LiSrAlF6 have been investigated by single crystal X-ray diffraction. Molecular orbital calculations were also carried out using cluster models based on the obtained structures. The crystallographic c-axis at 120 K in LiSrAlF6 became slightly elongated with respect to the 300 K lattice and the structure became more distorted. In contrast, there was uniform lattice parameter contraction in LiCaAlF6 and the structure changed minimally between 300 and 120 K. These structural variations support other studies of temperature dependent optical properties reported in the literature. 相似文献
176.
Norihiro Tokitoh Hiroyuki Suzuki Nobuhiro Takeda Takashi Kajiwara Takahiro Sasamori Renji Okazaki 《Silicon Chemistry》2002,1(5-6):313-319
In this paper, we present the reaction of an overcrowded silylene bearing a 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt) group with pivalonitrile and t-butylphosphaalkyne to give the corresponding [1+2] cycloadducts, 2H-azasilirene and 2H-phosphasilirene derivatives. This is the first exampleof the isolation of a stable 2H-azasilirene derivative, and the X-ray crystallographic analysis unambiguously revealed its three-membered ring structure in the solid state. In addition, DFT calculations supported three-membered ring character in the structures of the 2H-azasilirene and 2H-phosphasilirene. 相似文献
177.
Ru‐Qiang Zou Rui‐Qin Zhong Ling Jiang Yusuke Yamada Nobuhiro Kuriyama Qiang Xu 《化学:亚洲杂志》2006,1(4):536-543
The reaction of cadmium(II) perchlorate with urocanic acid under different conditions created three novel coordination compounds: [Cd2(L2)2‐(L3)2(H2O)8] ( 1 ), {[Cd(L)(L2)](H2O)1/2}n ( 2 ), and {[Cd(L3)2](H2O)3/2(EtOH)}n ( 3 ), in which L, L2, and L3 are three urocanate tautomers. Complex 1 consists of two separate mononuclear units with different urocanate tautomers, which self‐assemble into a 3D hydrogen‐bonding network constructed by alternating 2D layers, whereas complexes 2 and 3 self‐assemble into 3D alpha‐polonium and four‐fold interpenetrated diamondoid networks, respectively. The tautomerism of the urocanate ligands and the enormous structural diversity of their complexes are present in this system, which illustrates that the reaction temperature, pressure, and the metal ions themselves act cooperatively to tune the tautomerism of the ligands and the frameworks of their metal coordination compounds. The fluorescence‐emission and nitrogen‐adsorption properties of these complexes are also investigated. 相似文献
178.
A new type of an o-phenylene-bridged tetrathioether ligand tethered with extremely bulky substituents, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt) groups, at its terminal sulfur atoms, TbtS[(o-phenylene)S]3Tbt (1), was synthesized by taking advantage of the coupling reaction of thiols with iodobenzenes using Cu2O in 2,4,6-trimethylpyridine. Complexation of 1 with Na2PdCl4 gave the corresponding dichloropalladium(II) complex, [PdCl2(1)] (7). The X-ray structural analysis of 7 indicated that the central palladium metal is in a distorted octahedral environment, where the two inner sulfur atoms of 1 and the two chlorine atoms form a square planar arrangement around the palladium metal and the two terminal sulfur atoms of 1 weakly coordinate to the palladium center at the axial positions. In addition, a phenyl analogue of 1, PhS[(o-phenylene)S]3Ph (2), was synthesized by a method similar to that for 1. Reaction of 2 with Na2PdCl4 gave the corresponding dichloropalladium(II) complex, [PdCl2(2)] (8). X-ray crystallography of 8 showed a type of the structure different from the distorted octahedral structure in 7, i.e., a square planar arrangement around the central palladium atom with the one terminal sulfur atom of 2, its neighboring sulfur atom, and the two chlorine atoms. The results of the NMR studies on 8 in a CDCl3 solution were not consistent with the results of the X-ray crystallography and suggested the coordination of the two inner sulfur atoms of 2 to the palladium metal, although a possibility of the existence of the rapid interconversion among isomers could not be excluded. 相似文献
179.
The orbital relaxation energy is defined for single and double ionizations of valence electrons, and is calculated for CH4, NH3, H2O and HF molecules with the ab initio SCF method. It is shown that the orbital relaxation energy for the ionization from a bonding orbital is about half of that for a non-bonding orbital, and the orbital relaxation energy for the double ionization is about double of that for the single ionization. This result gives a theoretical foundation for the empirical method of interpret Auger electron spectra by using experimental single ionization potentials. 相似文献
180.
Yokota K Fukushi K Ishio N Sasayama N Nakayama Y Takeda S Wakida S 《Electrophoresis》2003,24(12-13):2244-2251
We describe an application of capillary zone electrophoresis (CZE) with transient isotachophoresis (ITP) as the on-line concentration procedure for the determination of iodide in seawater. The effective mobility of iodide was decreased by the addition of 10 mM cetyltrimethylammonium chloride (CTAC) to an artificial seawater background electrolyte (BGE) so that transient ITP functioned and iodide was separated from other coexisting anions such as bromide, nitrite, and nitrate in seawater samples. After sample injection, 600 mM acetate was separately injected into the capillary as the terminating ion to generate transient ITP. The limit of detection (LOD) for iodide was 3.0 microg/L. The LOD was obtained at a signal-to-noise ratio (S/N) of 3. The values of the relative standard deviation (RSD) of peak area, peak height, and migration time for iodide were 2.9, 2.1, and 0.6%. The proposed method was applied to the determination of iodide in seawater collected around the Osaka Bay. The results obtained by use of the calibration graph were agreed with those obtained by the addition of the standard solutions for iodide. 相似文献