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51.
52.
Three new zinc(II) complexes of [Zn(6-mbipy)(η2-NO3)2] (1), [Zn(6,6′-dmbipy)(η2-NO3)2] (2) and [Zn(5,5′-dmbipy)(η2–NO3)(H2O)2](NO3).H2O (3) were prepared from the reaction of 6-methyl-2,2′-bipyridine (6-mbipy), 6,6′-dimethyl-2,2′-bipyridine (6,6′-dmbipy) and 5,5′-dimethyl-2,2′-bipyridine (5,5′-dmbipy) with Zn(NO3)2·4H2O in methanol, respectively. These three complexes were thoroughly characterized by elemental analysis, thermal gravimetric analysis, differential thermal analysis, infrared, UV–Vis, 1H NMR and 13C{1H} NMR spectroscopy, and their structures have all been determined by the single-crystal X-ray diffraction. The luminescence spectra of the title complexes show that the intensity of their emission bands is stronger than the bands for the free ligands.  相似文献   
53.
A green and simple method has been developed for efficient preparation of diverse annulated 2-amino-3-cyano-4H-pyran derivatives in the presence of a low loading of tetraethylammonium 2-(carbamoyl)benzoate (TEACB), as a bifunctional organocatalyst, under solvent-free conditions using the ball milling technique. This procedure is a clean, transition-metal-free, and environmentally friendly approach that offers many advantages including short reaction times, high to quantitative yields, low cost, and straightforward work-up.  相似文献   
54.
Ni(II) complexes of [12]aneN4: 1,4,7,10-tetraazacyclododecane-2,3,8,9-tetraone; [14]aneN4: 1,4,8,11-tetraazacyclotetradecane-2,3,9,10-tetraone; Bzo2[12]aneN4: dibenzo-1,4,7,10-tetraazacyclododecane-2,3,8,9-tetraone and Bzo2[14]aneN4: dibenzo-1,4,8,11-tetraazacyclotetradecane-2,3,9,10-tetraone have been encapsulated in the nanopores of zeolite-Y by a two-step process in the liquid phase: (i) adsorption of [bis(diamine)nickel(II)]; [Ni(N–N)2]–NaY; in the supercages of the zeolite, and (ii) in situ condensation of the nickel(II) precursor complex with diethyloxalate. The new host-guest nanocatalyst (HGN) were characterized by several techniques: chemical analysis and spectroscopic methods (FT-IR, UV/Vis, XRD, BET, DRS) and then were used for oxidation of cyclohexene with molecular oxygen.  相似文献   
55.
 Lipase from Pseudomonas cepacia (PCL) catalyzes the regio- and stereoselective acylation of primary and secondary hydroxy groups in steroid side chains under irreversible transesterification conditions with vinyl acetate in organic solvents.  相似文献   
56.
Summary.  Lipase from Pseudomonas cepacia (PCL) catalyzes the regio- and stereoselective acylation of primary and secondary hydroxy groups in steroid side chains under irreversible transesterification conditions with vinyl acetate in organic solvents. Received December 20, 1999. Accepted December 31, 1999  相似文献   
57.
The synthesis of polysubstituted quinolines was accomplished through Friedländer annulation between 2‐aminoaryl ketones and different active methylene compounds at room temperature using ball‐milling technique in the presence of p‐toluenesulfonic acid. The mechanism of the reaction investigated by density functional theory‐based modeling is also reported. This study aims at giving insight into the mechanism of the Friedländer reaction in the presence of acid catalysts. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
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