小分子配体诱导合成N,N-二苄基二硫代氨基甲酸镉(II)配合物及晶体结构

4,4'-联吡啶与二苄基二硫代氨基甲酸镉配合物[Cd(DBTC)₂]₂ (1)反应得到加合物[Cd(DBTC)₂(4,4'-bipy)] (2) (DBTC＝N,N-二苄基二硫代氨基甲酸), 通过晶体结构分析及红外光谱等研究其结构与性质. 结果表明: 引入小分子配体会破坏[Cd(DBTC)₂]₂ (1)的二聚结构, 加入吡啶则得到单核的吡啶加合物[Cd(DBTC)₂py] (3), 而引入4,4'-联吡啶后其结构变为新型的一维链状结构的配位聚合物2, 这种结构在二硫代氨基甲酸金属配合物中少见报道. 也比较了不同配体如吡啶及4,4'-联吡啶对Cd(II)及Zn(II)配合物结构的影响.     

The Effects of Methylene Blue and Oxygen Concentration on the Photoinactivation of Qβ Bacteriophage

Abstract— Concentration effects of methylene blue (MB) and oxygen on the photoinactivation rate of Qβ bacteriophage were examined. The effect of initial virus concentration was verified on the similar f2 phage. The inactivation rate, k , is an increasing function of MB and O₂ concentration and shows saturation with respect to MB concentration. Thus the results suggest that MB must adsorb to Qβ sites and oxygen must be present for photoinactivation to occur. The inactivation rate is independent of the initial number of phage particles present before inactivation, indicating that inactivation does not depend upon interaction among viral particles or on surface effects. The results indicate that at least two different viral phenotypes exist within the wild-type Qβ and f2 populations: one susceptible and the other resistant.     

THE EFFECTS OF LIQUID HOLDING ON NEAR-UV(300–400 nm) IRRADIATED ESCHERICHIA COLI STRAINS DIFFERING IN NEAR AND FAR-UV RADIATION SENSITIVITY

Abstract— Stationary phase cells from four Escherichia coli strains differing in near- (nur vs. nur ₊) and far-UV (recAl vs. recA₊) radiation sensitivity were subjected to near-UV radiation (NUV) in 0.85% saline. Although the NUV-irradiated cultures yielded increased colony numbers following 24 h of liquid holding (LH), a fluctuation test for each experiment showed that the observed increases were not due to recovery but were in fact due to cell multiplication. The decline in viability observed after NUV with liquid holding using the fluctuation test was equivalent in strains RT2, 3 and 4 while the decline observed with RT1 was less marked. The discrepancy between LH involving cell densities of 10₈-10₉ and 1–4 cells/m/ can be resolved by assuming that with dense cell suspensions, NUV-induced membrane damage leads to leakage or lysis, supplying sufficient nutrients to allow growth of undamaged, surviving cells.     

13C-NMR. Spectroscopy of Naturally Occuring Substances. XLII. Conformational analysis of quebrachamine-like indole alkaloids and related substances

The ¹³C shifts of 16α- and 16β-substituted derivatives of quebrachamine, 14,15-dehydroquebrachamine, cleavamine, 15,20α-dihydrocleavamine and 15,20β-dihydrocleavamine are determined and correlated with possible conformations of these tetracycles. The method of analysis of the C(16) configuration of these compounds, which emanated from this study, is used for the determination of the configuration of the site of coupling of vindoline and cleavamine β-chloroindolenine.     

Synthesis, X-ray diffraction analysis and NMR studies of (Z)-2-methyl-3-triphenylstannyl-3-pentene-2-ol

The synthesis of (Z)-2-methyl-3-triphenylstannyl-3-pentene-2-ol and its characterization by an X-ray diffraction study and multinuclear NMR are reported. The tin atom exhibits a distorted tetrahedral SnC₄ geometry with the four Sn---C bond distances experimentally equivalent. The slight distortion from the ideal tetrahedral geometry is because of the presence of a weak intramolecular HO → Sn interaction of 3.012(3) Å which produces a loose four-membered ring. The title compound was characterized in solution by ¹H, ¹³C and ¹¹⁹Sn NMR, and the persistence of the weak intramolecular HO → Sn coordination in solution was revealed by ¹³C and ¹¹⁹Sn secondary isotope multiplet of partially labelled entities (SIMPLE-NMR) experiments.     

Long-range fluorine-proton coupling in 1,2,4-triazole derivatives

Several 1,2,4-triazole derivatives containing a 2-fluorophenyl substituent at either the 3- or 5-position and a methyl group at the 4-position were synthesized. These derivatives exhibit long-range ¹⁹F-¹H and ¹⁹F-¹³C through-space coupling in their ¹H and ¹³C nmr spectra between the fluorine and the 4-methyl group. The close spatial proximity of these nuclei was confirmed by X-ray analysis and by fluorine irradiated proton observe ({¹⁹F}-¹H) NOE difference spectroscopy.     

Dependence of the glass transition temperature of poly(methyl methacrylate) on tacticity and molecular weight

The preparation of five samples of poly(methyl methacrylate) covering a wide range of tacticity and their electron irradiation to produce series of varying molecular weight are described. The glass transition temperature T_g of each polymer was determined by DTA techniques. Plots of T_g and the reciprocal of the molecular weight are well fitted in every case by a straight line. The data are also fitted to the Gibbs-DiMarzio theory and the values of the energy and free-volume parameters obtained are discussed. A method of estimating T_g of pure syndiotactic poly(methyl methacrylate) by extrapolation is presented, the value obtained being 160°C.     

Oxygen binding of water-soluble cobalt porphyrins in aqueous solution

Water-soluble cobalt porphyrin 1Co and imidazole ligand 2 were synthesized. 1Co binds dioxygen in the presence of imidazole ligand 2 in aqueous solution. The formation of the oxygen adduct 2-1Co(O(2)) was studied using UV-vis and EPR spectroscopy. The impact of pH on the kinetic stability of the oxygen adduct was examined.     

Monitoring trace anion contamination in disk drive components

Ion chromatography was used to determine trace anionic contamination on the surface of hard disk drive components. These contaminants can have a detrimental effect on device reliability and yield. Disk drive components were soaked in deionized water and these extracts were analyzed for anions. The anions fluoride, acetate, formate, acrylate, methacrylate, chloride, nitrite, bromide, nitrate, benzoate, sulfate, oxalate, phthalate and phosphate were separated on a high-performance anion-exchange column and determined at concentrations less than 1 microg/l with suppressed conductivity detection. The extract solutions were analyzed either by injecting 1 ml or by preconcentrating 5 ml. We evaluated the performance of both methods.