Showing papers on "Selenourea published in 1992"
TL;DR: In this article, the size of microcrystals embedded in glasses changed with the amount of thiourea complexes in gels for the sulfides and with the immersion time of the porous glasses in selenourea solutions for the selenide.
Abstract: The sol-gel process has been studied to prepare non-linear optics glasses doped with Cd and Zn chalcogenide microcrystals. CdS- or ZnS-doped SiO 2 glasses were prepared by heat treatment of gels containing thiourea complexes of corresponding metal ions. CdSe-doped glasses were alternatively formed by immersing sol-gel-derived porous CdO SiO 2 glasses in methanol solutions of selenourea. The size of microcrystals embedded in glasses changed with the amount of thiourea complexes in gels for the sulfides and with the immersion time of the porous glasses in selenourea solutions for the selenide. Glasses containing these chalcogenide microcrystals showed quantum size effects in optical absorption spectra.
52 citations
TL;DR: One-pot synthesis of 4-substituted 2-amino- or 2-(arylamino) thiazoles has been achieved via treatment of ketones with [hydroxy(tosyloxy)iodo]benzene and thioureas in refluxing acetonitrile as discussed by the authors.
Abstract: A one-pot synthesis of 4-substituted 2-amino- or 2-(arylamino) thiazoles has been achieved via treatment of ketones with [hydroxy(tosyloxy)iodo]benzene and thioureas in refluxing acetonitrile. 1,3-Dicarbonyl compounds yield (5-acyl-4-methylthiazol-2-yl)-ammonium tosylates and the corresponding selenazol-2-yl compounds, respectively, upon reaction with [hydroxy(tosyloxy)iodo] benzene followed by the addition of thiourea or selenourea. The tosylate salts are converted to the corresponding free bases by treatment with sodium bicarbonate
47 citations
07 Dec 1992
TL;DR: The formation process of glasses doped with cadmium and zinc sulfide or selenide microcrystallites has been studied, along with the characterization of the glasses obtained.
Abstract: The formation process of glasses doped with cadmium and zinc sulfide or selenide microcrystallites has been studied, along with the characterization of the glasses obtained. Sulfide microcrystallite-doped SiO 2 glasses were prepared by the heat-treatment at around 400 degree(s)C of gels in which thiourea complexes were confined. The formation of thiourea complexes of Cd(NO 3 ) 2 and Zn(NO 3 ) 2 in the starting solutions to form gels was confirmed from IR and Raman spectra. The crystalline phase of microcrystallites doped was hexagonal for CdS and cubic for ZnS and their mean diameter varied with the amount of thiourea complexes added. The absorption edges of the semiconductor-doped glasses were found to be shifted to shorter wavelengths in reference to those of corresponding bulk semiconductors due to the quantum size embedded in gels only in the presence of L(+)- ascorbic acid as an antioxidant. Most of Se in the gels, however, was found to be lost within forming selenides of the heat-treatment, though the complexes themselves produced cubic CdSe or ZnSe by the heat-treatment at around 400 degree(s)C in air.
6 citations
2 citations