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951.
952.
Two new zinc(II) complexes have been synthesized and studied by single crystal X-ray diffraction method: [Zn(L1)Cl2]·2DMF (1) and [Zn(L2)Cl2]·DMF (2) (L1 = 3,3′-bis(2-benzimidazolyl)-2,2′-dipyridine, L2 = 3,3′-bis[2-bis(2-ethylbenzimidazolyl)]-2,2′-dipyridine). Compound
1 is monoclinic, C2/c, a = 23.142(3) ?, b = 11.845(1) ?, c = 14.735(3) ?; compound 2 is orthorhombic, C2221, a = 12.140(7) ?, b = 16.283(9) ?, c = 16.51(1) ?. In both compounds, Zn(II) cations are coordinated by two chlorine atoms and two benzimidazole nitrogen atoms
in a slightly distorted tetrahedron fashion. Structural features responsible for fluorescent properties of the complexes are
discussed. 相似文献
953.
Emanuel Makrlík Ji?í Dybal Ji?ina ?vor?íková Jan Budka Petr Vaňura 《Monatshefte für Chemie / Chemical Monthly》2010,287(1):507-510
Abstract
From extraction experiments in the two-phase water/nitrobenzene system, the stability constant of the silver ionophore IV (i.e., 5,11,17,23-tetra-tert-butyl-25,27-bis[2-(methylthio)ethoxy]calix[4]arene)–Ag+ complex in nitrobenzene saturated with water was determined. Furthermore, the most probable structure of the resulting complex was derived by means of density functional level of theory calculations. 相似文献954.
955.
Zhi‐An He Guang‐Zhou Lu Lin‐Lin Zhu Yong‐Xue Wang Fu‐Lin Yan Ji‐Xia Zhang 《中国化学会会志》2010,57(2):256-259
Two new ent‐kaurane diterpenoids, taihangexcisoidesin C (1) and its acetonide, taihangexcisoidesin D (2), along with 9 known compounds were isolated from the leaves of Isodon excisoides. The structures of the new compounds were elucidated using 1D and 2D NMR spectroscopy analysis. Compounds 3‐6 and 8‐9 were tested for their antibacterial activity against Escherichia coli, Staphylococcus aureus, S. epidermidis and S. saprophyticus. Compound 6 showed inhibitory effects on Staphylococcus aureus, S. epidermidis and S. saprophyticus MIC values 32, 16 and 16 μg/mL, respectively. All of the compounds didn't show effects on Escherichia coli (MIC > 10 mg/mL). 相似文献
956.
Mario Barbatti Jiří Pittner Marek Pederzoli Ute Werner Roland Mitrić Vlasta Bonačić-Koutecký Hans Lischka 《Chemical physics》2010
Non-adiabatic dynamics simulations were performed for pyrrole at time-dependent density functional theory level using the trajectory surface hopping approach. Initial conditions were prepared based on the UV-absorption spectrum so as to simulate monochromatic absorption in three distinct spectral regions. The results showed predominance of the NH-stretch mechanism for excited-state relaxation. With increasing initial energy, however, other mechanisms are activated as well, even though they still occurred for a minor fraction of the trajectories. Dynamics starting at the origin of the absorption spectrum exhibited internal conversion to the ground state with a time constant of 20 fs. In contrast, dynamics starting at higher energies gave rise to much longer time constants for internal conversion near 200 fs. 相似文献
957.
Hyeong Jin Yun Hyunjoo Lee Ji Bong Joo Nam Dong Kim Jongheop Yi 《Electrochemistry communications》2010,12(6):769-772
We describe a method tuning the band-gap energy (Eg) of visible light sensitive TiO2-xCx nanoparticle. Eg tends to become smaller with the increase in the amount of carbon dopant in TiO2-xCx nanoparticle due to the increase in excess electrons. Photo-catalytic oxidative activity, however, did not depend on only the value of Eg, but also the energy level of valence band. TiO1.96C0.04 nanoparticle having Eg of 2.6 eV showed outstanding performance in oxidative decomposition of phenol under the irradiation of visible light. 相似文献
958.
Hari Ji Singh Bhupesh Kumar Mishra Nand Kishor Gour 《Theoretical chemistry accounts》2010,125(1-2):57-64
The unimolecular decomposition reaction of CF3CCl2O radical has been investigated using theoretical methods. Two most important channels of decomposition occurring via C–C bond scission and Cl elimination have been considered during the present investigation. Ab initio quantum mechanical calculations are performed to get optimized structure and vibrational frequencies at DFT and MP2 levels of theory. Energetics are further refined by the application of a modified Gaussian-2 method, G2M(CC,MP2). The thermal rate constants for the decomposition reactions involved are evaluated using Canonical Transition State Theory (CTST) utilizing the ab initio data. Rate constants for C–C bond scission and Cl elimination are found to be 6.7 × 106 and 1.1 × 108 s?1, respectively, at 298 K and 1 atm pressure with an energy barrier of 8.6 and 6.5 kcal/mol, respectively. These values suggest that Cl elimination is the dominant process during the decomposition of the CF3CCl2O radical. Transition states are searched on the potential energy surface of the decomposition reactions involved and are characterized by the existence of only one imaginary frequency (NIMAG = 1) during frequency calculation. The existence of transition states on the corresponding potential energy surface is further ascertained by performing intrinsic reaction coordinate (IRC) calculation. 相似文献
959.
960.
Xiao‐Chi Ma Xiulan Xin Bao‐jing Zhang Sha Deng Ji‐hong Yao Chang‐yuan Wang Jian Cui Yan Tian Ke‐xin Liu 《Journal of separation science》2010,33(15):2272-2277
An efficient separation method of using high‐speed counter‐current chromatography was successfully established to directly purify cytotoxic transformed products of cinobufagin by Cordyceps militaris. The two‐phase solvent system composed of n‐hexane–ethyl acetate–methanol–water (4:6:3:4, v/v) was used in high‐speed counter‐current chromatography. A total of 9 mg of 4β,12α‐dihydroxyl‐cinobufagin ( 1 ), 15 mg of 12β‐hydroxyl‐cinobufagin ( 2 ), 8 mg of 5β‐hydroxyl‐cinobufagin ( 3 ), 12 mg of deacetylcinobufagin ( 4 ) and 6 mg of 3‐keto‐cinobufagin ( 5 ) were obtained in a one‐step separation from 400 mg of the crude extract with purity of 98.7, 97.2, 90.6, 99.1 and 99.4%, respectively, as determined by HPLC. Their chemical structures were identified on the basis of 1H‐NMR and 13C‐NMR technology. All products ( 1 – 5 ) showed the potent activities against human carcinoma cervicis (Hela) and malignant melanoma (A375) cells in vitro. 相似文献