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Shiv P Halasyamani - One of the best experts on this subject based on the ideXlab platform.
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new vanadium selenites centrosymmetric ca2 vo2 2 seo3 3 h2o 2 sr2 vo2 2 seo3 3 and ba v2o5 seo3 and noncentrosymmetric and polar a4 vo2 2 seo3 4 se2o5 a sr2 or pb2
Inorganic Chemistry, 2012Co-Authors: Jeongho Yeon, Sanghwan Kim, Sau Doan Nguyen, Hana Lee, Shiv P HalasyamaniAbstract:Five new vanadium selenites, Ca(2)(VO(2))(2)(SeO(3))(3)(H(2)O)(2), Sr(2)(VO(2))(2)(SeO(3))(3), Ba(V(2)O(5))(SeO(3)), Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), and Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), have been synthesized and characterized. Their crystal structures were determined by single crystal X-ray diffraction. The compounds exhibit one- or two-dimensional structures consisting of corner- and edge-shared VO(4), VO(5), VO(6), and SeO(3) polyhedra. Of the reported materials, A(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)) (A = Sr(2+) or Pb(2+)) are noncentrosymmetric (NCS) and polar. Powder second-harmonic generation (SHG) measurements revealed SHG efficiencies of approximately 130 and 150 × α-SiO(2) for Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)) and Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), respectively. Piezoelectric charge constants of 43 and 53 pm/V, and pyroelectric coefficients of -27 and -42 μC/m(2)·K at 70 °C were obtained for Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)) and Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), respectively. Frequency dependent polarization measurements confirmed that the materials are not ferroelectric, that is, the observed polarization cannot be reversed. In addition, the lone-pair on the Se(4+) cation may be considered as stereo-active consistent with calculations. For all of the reported materials, infrared, UV-vis, thermogravimetric, and differential thermal analysis measurements were performed. Crystal data: Ca(2)(VO(2))(2)(SeO(3))(3)(H(2)O)(2), Orthorhombic, Space Group Pnma (No. 62), a = 7.827(4) A, b = 16.764(5) A, c = 9.679(5) A, V = 1270.1(9) A(3), and Z = 4; Sr(2)(VO(2))(2)(SeO(3))(3), monoclinic, Space Group P2(1)/c (No. 12), a = 14.739(13) A, b = 9.788(8) A, c = 8.440(7) A, β = 96.881(11)°, V = 1208.8(18) A(3), and Z = 4; Ba(V(2)O(5))(SeO(3)), Orthorhombic, Space Group Pnma (No. 62), a = 13.9287(7) A, b = 5.3787(3) A, c = 8.9853(5) A, V = 673.16(6) A(3), and Z = 4; Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), Orthorhombic, Space Group Fdd2 (No. 43), a = 25.161(3) A, b = 12.1579(15) A, c = 12.8592(16) A, V = 3933.7(8) A(3), and Z = 8; Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), Orthorhombic, Space Group Fdd2 (No. 43), a = 25.029(2) A, b = 12.2147(10) A, c = 13.0154(10) A, V = 3979.1(6) A(3), and Z = 8.
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polar hexagonal tungsten bronze type oxides knbw2o9 rbnbw2o9 and ktaw2o9
Inorganic Chemistry, 2008Co-Authors: Hong Young Chang, T Sivakumar, Shiv P HalasyamaniAbstract:The synthesis, crystal structures, second-harmonic generation (SHG), piezoelectric, pyroelectric, and ferroelectric properties of three polar noncentrosymmetric (NCS) hexagonal tungsten bronze-type oxides are reported. The materials KNbW 2O 9, RbNbW 2O 9, and KTaW 2O 9 were synthesized by standard solid-state techniques and structurally characterized by laboratory powder X-ray diffraction. The compounds are isostructural, crystallizing in the polar NCS Space Group Cmm2. The materials exhibit a corner-shared MO 6 (M = Nb (5+)/W (6+) or Ta (5+)/W (6+)) octahedral framework, with K (+) or Rb (+) occupying the "hexagonal" tunnels. The d (0) transition metals, Nb (5+), Ta (5+), and W (6+), are displaced from the center of their oxide octahedra attributable to second-order Jahn-Teller effects. SHG measurements using 1064 nm radiation revealed frequency-doubling efficiencies ranging from 180 to 220 x alpha-SiO 2. Converse piezoelectric measurements resulted in d 33 values ranging from 10 to 41 pm V (-1). The total pyroelectric coefficient, p, at 50 degrees C ranged from -6.5 to -34.5 muC K (-1) m (-2). The reported materials are also ferroelectric, as demonstrated by hysteresis loops (polarization vs electric field). Spontaneous polarization values, P s, ranging from 2.1 to 8.4 muC cm (-2) were measured. The magnitudes of the SHG efficiency, piezoelectric response, pyroelectric coefficient, and ferroelectric polarization are strongly dependent on the out-of-center distortion of the d (0) transition metals. Structure-property relationships are discussed and explored. Crystal data: KNbW 2O 9, Orthorhombic, Space Group Cmm2 (No. 35), a = 21.9554(2) A, b = 12.60725(15) A, c = 3.87748(3) A, V = 1073.273(13) A (3), and Z = 6; RbNbW 2O 9, Orthorhombic, Space Group Cmm2 (No. 35), a = 22.00985(12) A, b = 12.66916(7) A, c = 3.8989(2) A, V = 1086.182(10) A (3), and Z = 6; KTaW 2O 9, Orthorhombic, Space Group Cmm2 (No. 35), a = 22.0025(2) A, b = 12.68532(14) A, c = 3.84456(4) A, V = 1073.05(2) A (3), and Z = 6.
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new layered uranium phosphate fluorides syntheses structures characterizations and ion exchange properties of a uo2 f hpo4 xh2o a cs rb k x 0 1
Inorganic Chemistry, 2006Co-Authors: Kang Min Ok, Jaewook Baek, Shiv P Halasyamani, Dermot OhareAbstract:Single crystals of three new layered uranium phosphate fluorides, A(UO2)F(HPO4)·xH2O (A = Cs+, Rb+, and K+; x = 0−1) have been synthesized by hydrothermal reactions using UO3, H3PO4, HF, and corresponding alkali metal halides as reagents. Although all three new materials have layered structures, each of them contains different structural motifs within the layer. While Cs(UO2)F(HPO4)·0.5H2O and Rb(UO2)F(HPO4) reveal noncentrosymmetric crystal structures, K(UO2)F(HPO4)·H2O crystallizes in a centrosymmetric Space Group. In addition, the ion-exchanged phases for all three materials are highly crystalline. Crystal data: Cs(UO2)F(HPO4)·0.5H2O, Orthorhombic, Space Group Pca21 (No. 29), with a = 25.656(5) A, b = 6.0394(12) A, c = 9.2072(18) A, and Z = 4; Rb(UO2)F(HPO4), Orthorhombic, Space Group Cmc21 (No. 36), with a = 17.719(4) A, b = 6.8771(14) A, c = 12.139(2) A, and Z = 8; K(UO2)F(HPO4)·H2O, monoclinic, P21/n (No. 14), with a = 6.7885(14) A, b = 8.7024(17) A, c = 12.020(2) A, β = 94.09(3)°, and Z = 4.
Gasper Tavcar - One of the best experts on this subject based on the ideXlab platform.
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crystal structure determination of pb2f2 hf sbf6 2 pbfsbf6 and ba hf af6 2 a as sb
Journal of Fluorine Chemistry, 2015Co-Authors: Melita Tramsek, Zoran Mazej, Evgeny Goreshnik, Gasper TavcarAbstract:Abstract The PbFSbF 6 and three compounds with hydrogen fluoride (HF) bonded directly to the metal centre (Pb 2 F 2 (HF)(SbF 6 ) 2 and Ba(HF)(AF 6 ) 2 : (A = As, Sb) were structurally characterized. Pb 2 F 2 (HF)(SbF 6 ) 2 crystallizes in the Orthorhombic Space Group Pbca with a = 13.0470(3) A, b = 10.3366(3) A, c = 18.2427(5) A, V = 2460.24(11) A 3 at 200 K, Z = 8. The main feature of its crystal structure is formation of the ribbon-like [Pb 4 F 4 ] 4+ units, which are further connected by SbF 6 − units into three dimensional framework. Similar [Pb–F] n n + ribbon-like polymers are observed in the crystal structure of PbFSbF 6 . The later crystallizes in the triclinic Space Group P 1 ¯ with a = 4.7439(5) A, b = 7.4001(6) A, c = 7.6940(8) A, α = 106.218(8)°, β = 102.220(9)°, γ = 90.479(7)°, V = 252.82(5) A 3 at 150 K, Z = 2. Single crystals of Ba(HF)(AF 6 ) 2 (A = Sb, As) were prepared and structurally characterized. These two compounds crystallize in the Orthorhombic Space Group Pbcn, Z = 8 with following cell dimensions; A = Sb: a = 11.0231(3) A, b = 16.0557(4) A, c = 11.7044(4) A, V = 2071.49(10) A 3 ; A = As: a = 10.7149(9) A, b = 15.7256(15) A, c = 11.2027(9) A, V = 1887.6(3) A 3 (both at 200 K), Z = 8.
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xef2 as a ligand in a coordination compound with the bf4 anion
Inorganic Chemistry, 2005Co-Authors: Gasper Tavcar, Boris ZemvaAbstract:The first tetrafluoroborate compound with XeF2 coordinated to a metal center, [Cd(XeF2)](BF4)2, has been synthesized. It crystallizes in monoclinic Space Group P21/a with a = 8.785(11) A, b = 9.079(2) A, c = 10.718(6) A, β = 110.824(6), and Z = 4. Its crystal structure and that of Cd(BF4)2 have been solved. The latter crystallizes in Orthorhombic Space Group Pbca. Both syntheses were performed in aHF as solvent, at room temperature, yielding colorless solids. The Raman spectra of the solids are in harmony with the crystallographic findings. [Cd(XeF2)](BF4)2 has been shown to be in equilibrium with XeF2 and Cd(BF4)2 in aHF.
Xingguo Chen - One of the best experts on this subject based on the ideXlab platform.
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hg2br3i a new mixed halide nonlinear optical material in the infrared region
CrystEngComm, 2013Co-Authors: Yin Huang, Xianggao Meng, Lei Kang, Yanjun Li, Cheng Zhong, Xingguo ChenAbstract:A new mixed halide, Hg2Br3I, has been synthesized in solution. It crystallizes in the noncentrosymmetric Orthorhombic Space Group Cmc21 (no. 36). In its single crystal, the molecules are arranged in a shuttle-like mode. Its powders show a phase-matchable second harmonic generation (SHG) response of approximately 0.7 times as strong as that of KTiOPO4 (KTP). It also exhibits a wide transparent range (from 0.45 to 38 μm) and a good thermal stability. These results indicate that Hg2Br3I is a promising candidate for NLO materials in the IR region.
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synthesis crystal structure and properties of a new candidate for nonlinear optical material in the ir region hg2bri3
Dalton Transactions, 2012Co-Authors: Yanjun Li, Xianggao Meng, Cheng Zhong, Meng Wang, Xingguo ChenAbstract:The synthesis, crystal structure, nonlinear optical (NLO) property and some other properties of a new material, Hg2BrI3, are reported. The crystal structure has been established by single crystal X-ray diffraction studies. Hg2BrI3 belongs to the HgBrI type and crystallizes in the Orthorhombic Space Group Cmc21 (No. 36). The compound shows a phase-matchable second harmonic generation (SHG) of about 1.2 times as strong as that of KTiOPO4 (KTP) based on the powder SHG measurement. It exhibits a wide transparency in the IR region (from 2.5 to 30 μm), and a good thermal stability. It is believed that Hg2BrI3 is a new candidate for NLO materials in the IR region.
Yoshiyuki Sakano - One of the best experts on this subject based on the ideXlab platform.
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crystallization and preliminary x ray analysis of thermoactinomyces vulgaris r 47 maltooligosaccharide metabolizing enzyme homologous to glucoamylase
Acta Crystallographica Section F-structural Biology and Crystallization Communications, 2005Co-Authors: Kazuhiro Ichikawa, Takashi Tonozuka, Shigehiro Kamitori, Atsushi Nishikawa, Masahiro Mizuno, Yoshihiro Tanabe, Yoshiyuki SakanoAbstract:A maltooligosaccharide-metabolizing enzyme from Thermoactinomyces vulgaris R-47 (TGA) homologous to glucoamylase degrades maltooligosaccharides more efficiently than starch, unlike fungal glucoamylases. TGA was crystallized and the state of the protein in solution was analyzed by gel-filtration chromatography. Diffraction data were collected to 3.31 A resolution. The TGA crystal belongs to the Orthorhombic Space Group P212121 or P21212, with unit-cell parameters a = 110.2, b = 317.6, c = 144.9 A, and is expected to contain five to eight TGA molecules per asymmetric unit. Gel-filtration and native PAGE analyses indicated that TGA exists as a dimer in solution. This is the first report of the crystallization of an oligomeric glucoamylase.
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crystallization and preliminary x ray analysis of thermoactinomyces vulgaris r 47 maltooligosaccharide metabolizing enzyme homologous to glucoamylase
Acta Crystallographica Section F-structural Biology and Crystallization Communications, 2005Co-Authors: Kazuhiro Ichikawa, Takashi Tonozuka, Shigehiro Kamitori, Atsushi Nishikawa, Masahiro Mizuno, Yoshihiro Tanabe, Yoshiyuki SakanoAbstract:A maltooligosaccharide-metabolizing enzyme from Thermoactinomyces vulgaris R-47 (TGA) homologous to glucoamylase degrades maltooligosaccharides more efficiently than starch, unlike fungal glucoamylases. TGA was crystallized and the state of the protein in solution was analyzed by gel-filtration chromatography. Diffraction data were collected to 3.31 A resolution. The TGA crystal belongs to the Orthorhombic Space Group P212121 or P21212, with unit-cell parameters a = 110.2, b = 317.6, c = 144.9 A, and is expected to contain five to eight TGA molecules per asymmetric unit. Gel-filtration and native PAGE analyses indicated that TGA exists as a dimer in solution. This is the first report of the crystallization of an oligomeric glucoamylase.
Igor Polikarpov - One of the best experts on this subject based on the ideXlab platform.
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crystal structures of bovine beta lactoglobulin in the Orthorhombic Space Group c222 1 structural differences between genetic variants a and b and features of the tanford transition
FEBS Journal, 2001Co-Authors: Kesley M G Oliveira, Vera Lucia Valentemesquita, Michelle M Botelho, Lindsay Sawyer, Sergio T Ferreira, Igor PolikarpovAbstract:The crystal structures of β-lactoglobulin genetic variants A and B have been determined in the Orthorhombic Space Group C2221 (lattice Y) by X-ray diffraction at 2.0 A and 1.95 A resolution, respectively. The structural comparison shows that both variants exhibit the open conformation of the EF loop at the pH of crystallization (pH 7.9), in contrast to what has been reported for the same genetic variants at pH 7.1 in the trigonal Space Group P3221 (lattice Z) [Qin, B.Y., Bewley, M.C., Creamer, L.K., Baker, E.N. & Jameson, G.B. (1999) Protein Sci.8, 75–83]. Furthermore, it was found that the stereochemical environment of Tyr42 changes significantly with pH variation between pH 7 and pH 8. This may provide a structural explanation for an as yet unexplained feature of the Tanford transition, namely the increase in exposure of a tyrosine residue.
