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Single Crystal X-ray Diffraction Studies (single + crystal_x-ray_diffraction_studies)

Distribution by Scientific Domains

Physics and Astronomy	50%
Chemistry	50%

Selected Abstracts

Novel regioselective synthesis of 3,H,4H -spiro[chromene-3,2,-[1,3,4]thiadiazol]-4-one containing compounds

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2006
Mohamed I. Hegab
A variety of 3,,5,-diaryl-3,H,4,H -dispiro[cyclohexane-1,2,-chromene-3,,2,-[1,3,4]thiadiazol]-4,-ones 3a-c were synthesized regioselectively through the reaction of 4,H,5H -trispiro[cyclohexane-1,2,-chromene-3,,2,-[1,3,4]oxadithiino[5,6- c]chromene-5,,1,,-cyclohexan]-4,-one (1) with nitrilimines (generated in situ via triethylamine dehydrohalogenation of the corresponding hydrazonoyl chlorides 2a-c) in refluxing dry toluene. Single crystal X-ray diffraction studies of 3a,b add support for the established structure. Similarly, 3,,5,-diaryl-2,2-dimethyl-3,H,4H -spiro[chromene-3,2,-[1,3,4]thiadiazol]-4-ones 5a-c were obtained in a regioselective manner through the reaction of 2,2,5,,5,-tetramethyl-4H,5,H -spiro[chromene-3,2,-[1,3,4]oxadithiino[5,6- c]chromen]-4-one (4a) with nitrilimines under similar reaction conditions. On the other hand, reaction of 2,5,-diethyl-2,5,-dimethyl-4H,5,H -spiro[chromene-3,2,-[1,3,4]oxadithiino-[5,6- c]chromen]-4-one (4b) with nitrilimines in refluxing dry toluene afforded the corresponding 3,,5,-diaryl-2-ethyl-2-methyl-3,H,4H -spiro[chromene-3,2,-[1,3,4]thiadiazol]-4-ones 5d-f as two unisolable diastereoisomeric forms. [source]

Single crystal X-ray study of the modulated structure in Ga2XTe3 with the defect zinc-blende structure

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2009
S. Kashida
Abstract Ga2Te3 crystallizes into the zinc-blende structure, where one third of the cation sites is vacant. Single crystal X-ray diffraction studies on quenched and annealed Ga2Te3 and CuGaTe2 crystals are reported. The obtained diffraction maps show, other than the zinc-blende type main reflections, satellite reflections at q1,1/17[110]c in quenched Ga2Te3 crystals and q2,1/20[210]c in annealed Ga2Te3 crystals, where the subscript c means the cubic sub-lattice. The analysis of the satellite reflections shows that the modulation is two dimensional, and is ascribed to a coupled mode of the amplitude type modulation caused by Ga vacancies and the displacive modulation of surrounding Te atoms, which has the polarization vector along the <001>c direction. The nature of the atomic modulations is discussed and the origin of the modulation is ascribed to Jahn-Teller type distortions around Ga vacancies. The experiments done on CuGaTe2 crystals indicate that the cation disorder compound sphalerite type CuGaTe2 contain the same modulated structure as Ga2Te3 crystals, but the cation ordered compound chalcopyrite type CuGaTe2 does not show the modulation. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Syntheses, Structures and Luminescence Properties of Ln-Coordination Polymers Based on Flexible Thiodiacetic Acid Ligand

CHINESE JOURNAL OF CHEMISTRY, Issue 8 2009
Xiangyang HOU
Abstract Two novel lanthanide complexes with the formulas [Ln2(tda)3(H2O)2]n [Ln=Sm (1), Dy (2), H2tda=thiodiacetic acid] have been prepared by using the corresponding lanthanide salt and H2tda under hydrothermal conditions. Single crystal X-ray diffraction studies show that the two compounds are isostructural and present a 2D network based on the 1D metallic chain, in which an edge-sharing dinuclear polyhedral [Ln2O16] was found to be the building unit of the 1D chains. Interestingly, in the network, the tda ligands exhibit two different coordination modes, including the mode La: bis(syn,syn -bridging bidentate, chelating-bridging tridentate), and mode Lb: bis(chelating- bridging tridentate, syn, anti- bridging bidentate). Furthermore, through the tda ligand in modes La and Lb, the 1D metallic chains are cross-linked to generate a 2D network structure with (3,4,5,6)-connected (47·68)(44·66)(45·6)- (46)(43) topology. Photoluminescence measurements indicate that the dysprosium complex is yellow emitters, and the samarium complex shows salmon pink light emission in the solid state at room temperature. [source]

XRD, thermal, FTIR and SEM studies on gel grown ,-glycine crystals

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2007
E. Ramachandran
Abstract Glycine is the smallest among amino acids. The polymorphs, ,- and ,-forms of glycine were crystallized in silica gel by reduction of solubility method. The grown crystals were characterized by single crystal X-ray diffraction studies and density determination. Fourier transform infrared spectroscopic studies and thermogravimetric analysis of ,-glycine were also conducted. Morphological and scanning electron microscopic (SEM) studies were also made and compared with the crystal packing. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]