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61.
Vladimir L. Kolesnichenko Victor B. Rybakov Leonid A. Aslanov Sergei V. Volkov 《Journal of Cluster Science》1997,8(1):27-45
Thioselenohalide complexes Mo2(μ-S2)2Cl6(SeCl2)2 (I), Mo2(μ-S2)2Br6(SeBr2)2 (II), and W2(μ-S2)2Br6(SeBr2)2 (III) were synthesized by the reactions of corresponding metal halides or carbonyls or molybdenum metal with excesses of S2 X 2+Se2 X 2 mixtures. The complex W2(μ-S2)2Cl6(SeCl2)2 (IV) was obtained by an exchange reaction between (III) and excess of Se2Cl2. Coordination of the neutral SeX 2 ligands to thiohalidesM 2(μ-S2)2 X 6 results in higher thermal stability, and suggests the possibility to synthesize SeX 2 complexes of the unstable parent tungsten thiohalides. An unusual oxidative addition reaction of (I) was detected: {fx27-1} Both (I) and (IV) were characterized by X-ray crystal structure analysis. They are isostructural and form discrete molecules. Bridging S 2 2? ligands are coordinated perpendicularly to the metal-metal bond;d(M?M)=2.8066 Å and 2.793 Å for I and IV, respectively. Nonequivalence of chlorine atoms which are bound to the metal atom, relate to nonequivalence of halogen atoms in the complexesM 2(μ?S2)2 X 8 2? . Chlorine atomstrans to SeCl2 ligands form short bonds with the metal; the corresponding35Cl NQR frequency is increased. The selenium dichloride ligand is ambidentate. The selenium atom binds as a donor to the metal and as an acceptor to two chlorine atoms which are also bound covalently to the same metal atom. 相似文献
62.
Victor V. Borovkov Michael Anikin Kiyotaka Wasa Yoshiteru Sakata 《Photochemistry and photobiology》1996,63(4):477-482
Abstract— Structurally controlled aggregation course for five porphyrins (etioporphyrin [EP], 5-mono- and 5,15-di-[ p -tol-yl]etioporphyrin [TP and DTP], 5,10,15,20-tetrakis[ p -tol-y1]porphin [TTP], and 5,10,15,20-tetrakis[3,5-di- tert -bu-tylphenyl]porphin [TBP]) in dipalmitoyl-phosphatidyl-choline liposomes has been monitored by fluorescence and absorption spectroscopy. While TBP shows no tendency to aggregate in liposomes, EP, TP, DTP and TTP form a porphyrin-enriched domain in membrane interior with time. The further aggregation steps within porphyrin clusters resulting in formation of stacked porphyrin aggregates have been observed for EP, TP and DTP. 相似文献
63.
A mesoporous silica-supported uranyl material (U(aq)O(2)(2+)-silica) was prepared by a co-condensation method. Our approach involves an I(-)M(+)S(-) scheme, where the electrostatic interaction between the anionic inorganic precursor (I(-)), surfactant (S(-)), and cationic mediator (M(+)) provides the basis for the stability of the composite material. The synthesis was carried out under acidic conditions, where the anionic sodium dodecyl sulfate provided the template for the uranyl cation and silicate to condense. Excitation with visible or near-UV light of aqueous suspensions of U(aq)O(2)(2+)-silica generates an excited state that decays with k(0) = 1.5 x 10(4) s(-1). The reaction of the excited state with aliphatic alcohols exhibits kinetic saturation and concentration-dependent kinetic isotope effects. For 2-propanol, the value of k(C)3(H)7(OH)/k(C)()3(D)7(OH) decreases from 2.0 at low alcohol concentrations to 1.0 in the saturation regime at high alcohol concentrations. Taken together, the data describe a kinetic system controlled by chemical reaction at one extreme and diffusion at the other. At low [alcohol], the second-order rate constants for the reaction of silica-U(aq)O(2)(2+) with methanol, 2-propanol, 2-butanol, and 2-pentanol are comparable to the rate constants obtained for these alcohols in homogeneous aqueous solutions containing H(3)PO(4). Under slow steady-state photolysis in O(2)-saturated suspensions, U(aq)O(2)(2+)-silica acts as a photocatalyst for the oxidation of alcohols with O(2). 相似文献
64.
Gabriela Ionita Victor Sahini 《Journal of inclusion phenomena and macrocyclic chemistry》2004,50(3-4):183-186
The influence of certain thermal treatments on the reactivity of bovine serum albumin (denaturation followed by renaturation in three different cooling conditions) was studied monitoring the kinetics of oxidation of BSA with two water-soluble stable hydrazyl radicals. The results showed that the addition to the reaction mixture of -cyclodextrin and -cyclodextrin decreases the oxidation rate, probably due to the encapsulation of terminal amino acid rests by the cyclodextrins cavity. -Cyclodextrin protects more efficiently the albumin probes than -cyclodextrin. The denatured albumin probes are more reactive than natural albumin as a consequence of the reorienting of the hydrophobic rests of albumin molecule to their surface. 相似文献
65.
The reaction of epibromohydrin with hydroxyquinazolin-2-(1H)one derivatives. Novel oxazine formation
Mary Lou Cotter Victor Bandurco Elizabeth Wong Zoltan G. Hajos 《Journal of heterocyclic chemistry》1979,16(3):623-624
Epibromohydrin was found to react with 7-hydroxy-2-methylpyrrolo[1,2-c]quinazolin-5(6H)-one ( 4 ) in the presence of sodium hydroxide to form the novel oxazine 5 . The structure of compound 5 was proven by cmr and pmr analysis. 相似文献
66.
Propane fuel cells using H(3)PO(4)-doped polybenzimidazole polymer membranes produce low and unsustainable current densities at temperatures up to 250 degrees C under anhydrous conditions. Stable intermediate species blocked the surface of noble metal anode catalysts, and the intermediate species could not react further into desorbable final products. In contrast, when water was introduced by light humidification (S(r) 0.08%) of the propane stream, sustainable and higher current densities were achieved. Water participated in the reaction sequence to form surface-bound hydrocarbon and then oxygen-containing intermediates and thereby generated CO and CO(2) as the only carbon-containing products. 相似文献
67.
Berezkin Victor G. Mardanov Robert G. Moiseew Aleksey A. Malinowska Irena Różyło Jan K. 《平面色谱法杂志一现代薄层色谱法》2002,15(5):377-379
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
68.
Marina S. Fonari Victor Ch. Kravtsov Yurii A. Simonov Edward V. Ganin Vladimir O. Gelmboldt Janusz Lipowski 《Journal of inclusion phenomena and macrocyclic chemistry》2001,39(1-2):85-89
The crystalline host–guest type complex [(18-crown-6NH4)2][SiF6]4H2Ohas been obtained as the result of the interaction of SiF42NH3 with 18-crown-6 (18C6) in an aqueous medium. Crystal data: monoclinic, space groupC 2 c, a=26.541(2), b=8.363(2), c=20.469(2) Å, = 122.43(1)°and Z=4. The final R-value is 0.070 for 3253 reflections with I 2(I).The crystals consist of the complex [NH418C6]+ cations, [SiF6]2-anions and water molecules. The ammonium cation is hydrogen bonded by three of its H-atoms to the crown ether oxygen atoms with N(1) O separations2.923(5)–2.940(5) Å and by the fourth H-atom to the fluorine atom of thehexafluorosilicate anion, the N(1)F(4) distance being 2.797(6) Å.The conformation of the macrocycle and the hydrogen-bond geometry in thecomplex cation closely resemble those in related adducts between 18-crown-6and ammonium salts. All crystal components are connected via a system of hydrogen bonds into a ribbon along the b axis in the unit cell. 相似文献
69.
Synthesis of some dibenzodiazepinone derivatives as potent and m2-selective antimuscarinic compounds
Victor I. Cohen Biyun Jin Miriam S. Gitler Rosanna A. La De Cruz Waclaw J. Rzeszotarski Barry R. Zeeberg Jesse Baumgold Richard C. Reba 《Journal of heterocyclic chemistry》1994,31(4):787-791
Two series of 5-[[4-[4-(dialkylamino)butyl]-l-cyclohexyl]acetyl], and 5-[(dialkylamino)acyl]-10,11-dihydro-5H- dibenzo[b,e][1,4]diazepin-11-ones were synthesized as potential m2-selective ligands 1,2. Their affinity and selectivity for the muscarinic cholinergic receptor m-AChR subtypes were determined. Replacing a nitrogen with CH in the piperidine ring of 5-[[4-[4-(dialkylamino)butyl]-l-piperidinyl]acetyl]-10,11-dihydro-5H-dibenzo-[b,e][1,4]diazepin-11-ones 3 significantly altered the affinity and selectivity to the muscarinic receptor subtypes. 相似文献
70.
Using normal coordinate analysis, the infrared spectrum of cyclopentanone has been computed as the geometry is modified from the planar form to those in which the geometry about the 5-membered ring looks like 2-norbornanone and also like 7-norbornanone. The computed v
co of cyclopentanone is 1739.9 cm–1 compared to the experimental value of 1740 cm–1.As the cyclopentanone ring is deformed to resemble either the 2-norbornanone or the 7-norbornanone ring system, the computed v
co is too low using the force fields that give good agreement with experimental value for cyclopentanone. The carbonyl force constant had to be increased from 9.7 to 10.0 mdynes/Å for the 2-norbornanone-like model and to 10.4 mdynes/Å for the 7-model system to give v
co values in agreement with the experimental values.
Zusammenfassung Mit Hilfe der Normalkoordinaten-Analyse wird das Infrarotspektrum des Zyklopentanons berechnet, wobei die Geometrie von der planaren Form bis zu der Form, bei der die Geometrie am Fünfring derjenigen des 2-Norbornanons oder auch des 7-Norbornanons ähnlich wird, variiert wird. Der berechnete Wert von v co des Zyklopentanons ist 1739,9 cm–1, während der experimentelle Wert 1740 cm–1 beträgt. Bei den angegebenen Deformationen des Zyklopentanonrings wird der berechnete Wert von v co zu niedrig, wenn man die Kraftfelder zugrunde legt, die für das Zyklopentanon gute Übereinstimmung mit dem Experiment liefern. Die Carbonylkraftkonstanten mußten von 9,7 auf 10,0 m dyn/Å für das 2-Norbornanon-Modell sowie auf 10,4 m dyn/Å für das 7-Norbornanon erhöht werden, um den Wert von v co in Übereinstimmung mit dem Experiment zu bringen.
Résumé Le spectre infra-rouge de la cyclopentanone a été calculé en employant l'analyse en coordonnées normales lorsque l'on modifie la géométrie depuis la forme plane jusqu'aux formes o u les configurations sur le noyau pentagonal ressemblent à celles de la 2-norbornanone et de la 7-norbornanone. La fréquence co calculée pour la cyclopentanone est 1739.8 cm–1 comparée à la valeur expérimentale de 1740 cm–1. Lorsque l'on déforme le cycle de la cyclopentanone comme indiqué ci-dessus, la valeur calculée de co est trop faible si l'on emploie les champs de force qui donnent un bon accord avec la valeur expérimentale pour la cyclopentanone. La constante de force du carbonyle doit etre augmentée de 9,7 à 10,0 mdynes/Å pour le modèle analogue à la 2-norbornanone et de 9,7 à 10,4 mdynes/Å pour le modèle analogue à la 7-norbornanone.相似文献