Unit Cell Parameters (unit + cell_parameter)

Distribution by Scientific Domains

Selected Abstracts

Synthesis and characterization of Cu3TaIn3Se7 and CuTa2InTe4

P. Grima-Gallardo
Abstract Polycrystalline samples of Cu3TaIn3Se7 and CuTa2InTe4 were synthesized by the usual melt and anneal technique. X-ray powder diffraction showed a single phase behavior for both samples with tetragonal symmetry and unit cell parameter values a = 5.794 0.002 , c = 11.66 0.01 , c /a = 2.01, V = 391 1 3 and a = 6.193 0.001 , c = 12.400 0.002 , c /a = 2.00, V = 475 1 3, respectively. Differential thermal analysis (DTA) measurements suggested a complicated behavior near the melting point with several thermal transitions observed in the heating and cooling runs. From the shape of the DTA peaks it was deduced that the melting is incongruent for both materials. Magnetic susceptibility measurements (zero-field cooling and field cooling) indicated an antiferromagnetic character with transition temperatures of T = 70 K (Cu3TaIn3Se7) and 42 K (CuTa2InTe4). A spin,glass transition was observed in Cu3TaIn3Se7 with Tf , 50 K. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Comments on papers reporting IR-spectra and other data of alleged L-alanine alaninium nitrate and L-alanine sodium nitrate crystals

M. Fleck
Abstract We argue that the IR- and Raman-spectra of "L-alanine alaninium nitrate" given in "Investigation on the growth, optical behaviour and factor group of an NLO crystal: L-Alanine Alaninium nitrate" by Aravindan et al., Cryst. Res. Technol. 42, 1097 (2007), actually concern L-Alanine. Correspondingly, the data presented in "A comparative study on the growth and characterization of nonlinear optical amino acid crystals: L-Alanine (LA) and L-alanine alaninium nitrate (LAAN)" by Aravindan et al., Spectrochim. Acta A 71, 297 (2008), seems to be erroneous, as is "Synthesis, Growth, and Characterization of a New Semiorganic Nonlinear Optical Crystal: L-Alanine Sodium Nitrate (LASN)", Sethuraman, et al., Cryst. Growth Des. 8, 1863 (2008). In these papers properties and data were reported for L-Alanine compounds that actually are L-Alanine crystals and, in addition, unit cell parameters were given that seem to have been copied from other papers. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Crystal structure characterization of the quaternary compounds CuFeAlSe3 and CuFeGaSe3

G. E. Delgado
Abstract The crystal structure of the chalcogenide compounds CuFeAlSe3 and CuFeGaSe3, belonging to the system I-II-III-III3, were characterized using X-ray powder diffraction data. Both compounds crystallize in the tetragonal space group P42c (N 112), Z = 1, with unit cell parameters a = 5.609(1) , c = 10.963(2) for CuFeAlSe3 and a = 5.6165(3) , c = 11.075(1) for CuFeGaSe3. These compounds are isostructural with CuFeInSe3, and have a normal adamantane structure. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Structural study of the semimagnetic semiconductor Zn0.5Mn0.5In2Te4

G. E. Delgado
Abstract The semimagnetic semiconductor alloy Zn0.5Mn0.5In2Te4 was refined from an X-ray powder diffraction pattern using the Rietveld method. This compound crystallizes in the space group I42m (N 121), Z = 2, with unit cell parameters a = 6.1738(1) , c = 12.3572(4) , V = 471.00(2) 3, c/a = 2.00. This material crystallizes in a stannite-type structure. ( 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Synthesis, crystal structure and vibrational characterization of bis-,-peroxo-hexacarbonatodicerate(IV) complexes of rubidium and cesium

N.-P. Pook
Abstract The new compounds Rb8[Ce(O2)(CO3)3]2 12 H2O (1) and Cs8[Ce(O2)(CO3)3]2 10 H2O (2) were obtained from the reaction of hydrogen peroxide and Ce(III) in saturated alkali carbonate solutions. The crystal structures and the unit cell parameters of (1) triclinic, P-1 with a = 8.973(2) , b = 10.815(2) , c = 11.130(3) , , = 66.992(2), , = 68.337(2), , = 74.639(2), VEZ = 914.7(4) 3, Z = 2, and (2) orthorhombic, Pbca, a = 19.3840(16) , b = 18.528(2) , c = 10.487(3) , VEZ = 3766.4(13) 3, Z = 8, were determined. Both compounds contain the bis--peroxo-hexacarbonatodicerate(IV)-ion, [(CO3)3Ce(O2)2Ce(CO3)3]8- . IR and Raman spectra were measured and discussed. ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Crystal structure of a ternary mononuclear copper (II) complex: 4-chloro-3-methyl-6[(N-2-picolyl)-1,-iminomethyl]phenolato copper(II)perchlorate

S. M. Malathy Sony
Abstract The complex crystallizes in monoclinic space group P21/n with unit cell parameters a = 7.295(4), b = 19.627(5), c = 12.770(4) , , = 101.25(4), V = 1793.2(12) 3, Z = 4, , = 1.684 Mg/m3 at T = 293(2)K. The structure was solved by Patterson method and refined by full-matrix least-squares procedures to final R = 0.0387 using 2906 observed reflections. The asymmetric unit of the complex contains a mononuclear tridentate ligand, a perchlorate group and a methanol molecule. The compound crystallizes as parallel layers of polymeric complex bridged through perchloarate groups. The molecular CuN2OO,O,,2 chromophore involves an elongated rhombic octahedral structure and the Cu-ligand bond shows greater disparity. The five-membered chelate ring and the pyridine ring lie in the same plane while the six membered chelate ring assumes sofa conformation. A strong O-H,O inter molecular interaction plays a key role in the formation of dimer along b-axis. ( 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Synthesis, structural and thermal studies of tetrathioureacopper(I) chloride crystals

M. Dhandapani
Abstract Tetrathioureacopper(I) chloride, hereafter abbreviated as TCC, was synthesised and single crystals were obtained from saturated aqueous solution by slow evaporation (solution growth) method at room temperature. The crystals obtained are bright, colourless and transparent having well defined external faces. The grown crystals were characterized through elemental analysis, single crystal X-ray diffraction study, thermal analysis, electron spin resonance spectroscopy and Fourier Transform infrared spectroscopy. The elemental analysis confirms the stoichiometry of the compound. The single crystal diffraction studies indicate that TCC crystallises in the tetragonal lattice and the unit cell parameters are a = b = 13.4082 , c = 13.8074 , V = 2482.29 3, , = , = , = 90. Space group and the number of molecules per unit cell (Z) are found to be P41212 and 8 respectively. The TG curve of the sample shows a prolonged decomposition from 210 to 628.3 C, from which the decomposition pattern has been formulated. The endothermic peaks in the DTA curve indicate melting and decomposition of the compound at 165.2 and 633.8 C respectively. An exothermic peak in high temperature DSC indicates a phase transition in the compound at 274.8 C. Thermal anomalies observed in the low temperature DSC at ,163.3, ,152.0, ,141.5, ,108.3, 1.0 and 12.1 C in the heating run and ,157.1 and ,153.9 C in the cooling run reveal first order phase transitions in the crystal. The peaks observed at ,146.2 C in both the heating and cooling runs suggest occurrence of a second order phase transition in this compound. The IR spectroscopic data were used to assign the characteristic vibrational frequencies of various groups present in the compound. The ESR study confirms that the copper is in the +1 oxidation state in the complex. ( 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Crystal structure of N-[(1Z)-1-(3-methyl-3-phenylcyclobutyl)-2-thiomorpholin-4-ylethylidene] thiourea

U. Sar
Abstract The crystal structure of N-[(1Z)-1-(3-methyl-3-phenylcyclobutyl)-2-thiomorpholin-4-ylethylidene] thiourea (C18H26N4S2) has been determined by X-ray crystallographic techniques. The compound crystallizes in the orthorhombic space group Pbca, with unit cell parameters: a = 15.692(3), b = 20.803(8), c = 11.979(6), Z = 8, V = 3911(7)3. The crystal structure was solved by direct methods and refined by full-matrix least squares to a final R-value of 0.084 for 1447 observed reflections [I > 2, ( I ) ]. In the thiosemicarbazide moiety, the S = C bond length is 1.656(6), N-C-N angle is 115.6(5). The crystal structure is stabilized by the intermolecular N-H...S hydrogen bonds. ( 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Growth and characterization of undoped, Sr2+ -, and Mn2+ -doped ammonium tetrachlorozincate

M. A. Gaffar
Abstract Crystals of ammonium tetrachlorozincate (AZC) undoped and doped with Sr2+ or Mn2+ in different concentrations were grown by the slow evaporation method from an aqueous solution. The crystal morphology changed considerably by doping. The dopant concentration in the crystals was measured by the atomic absorption technique. Slight changes in the unit cell parameters of AZC after doping with Sr2+ - or Mn2+ have been detected. Optical absorption measurements indicated strong influence of Sr2+ and Mn2+ doping. The optical energy gap at room temperature decreased continuously with increasing Sr2+ and Mn2+ concentration but with two different rates. The dc conductivity was also measured as a function of temperature for the undoped and two samples doped with 0.144 Sr2+ and 0.191 Mn2+ and the results were compared. Positions possibly occupied by Sr2+ and Mn2+ cations in AZC lattice have been identified. ( 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Ca for Er substitution in tetragonal ErPO4 H2O crystallised from phosphoric acid solution

R. Kijkowska
Abstract Erbium phosphate monohydrate with limited Ca for Er substitution, obtained through crystallisation from boiling phosphoric acid solution has been characterised by X-ray diffraction, Ir-spectroscopy and thermal analysis (TGA-DTA) methods. The difference in the electric charge between di-valent calcium and tri-valent erbium in the solid crystallised was compensated by simultaneous substitution of HPO42- for PO43- . Ca incorporation in erbium phosphate made expansion of tetragonal ErPO4 H2O unit cell. After ignition at 900 C the tetragonal crystal modification was maintained but the unit cell parameters of all the investigated phosphates, whether Ca-substituted or Ca-free, contracted to the same level. The unique contraction of the unit cell was resulted from recrystallisation of Ca-substituted into Ca-free erbium phosphate, while Ca was transferred into Ca(PO3)2 formed as a separate phase. ( 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Mu-35: A Fluorogallophosphate Obtained by In Situ Generation of the Template

Louwanda Lakiss
Abstract A two-dimensional microporous fluorogallophosphate, named Mu-35, closely related to ULM-8, was hydrothermally synthesized by in situ generation of the structure-directing agent. The precursor of the structure-directing agent is ethylformamide, which is generated in situ by decomposition, and goes on to form ethylamine molecules that act as templates in the medium used for the synthesis. The fluorogallophosphate Mu-35 (Mu is Mulhouse), Ga3(PO4)2(HPO4)F3(C2H8N)2(C2H7N)0.5 (Z = 8), crystallizes in the orthorhombic space group Pbcn with the following unit cell parameters: a = 22.117(1), b = 17.3740(8), c = 10.1550(4) . The structure of fluorogallophosphate Mu-35 was determined from single-crystal XRD data. It exhibits anionic layers composed of an unusual arrangement of three-, five-, and eight-membered rings (MR) [Ga2PO2F, Ga3P2O4F, and Ga3P3O8, respectively], and intercalated by protonated and nonprotonated ethylamine molecules. Mu-35 was also characterized by powder XRD, SEM, elemental and thermal analyses, and solid-state NMR spectroscopy (1H, 13C, 19F, and 31P MAS and 1H- 31P HETCOR experiments). ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

One-Dimensional Oxalato-Bridged Metal(II) Complexes with 4 - Amino-1,2,4-triazole as Apical Ligand

Urko Garca-Couceiro
Abstract The synthesis, chemical characterization, thermal behavior and magnetic properties of six new one-dimensional oxalato-bridged metal(II) complexes of formula [M(,-ox)(4atr)2]n [MII = Cu (1), Ni (2), Co (3), Zn (4), Fe(5)] and [Cd(,-ox)(4atr)2(H2O)]n (6) (ox = oxalato dianion, 4atr = 4-amino-1,2,4-triazole) are reported. The crystal structures of 1 and 6 have been solved by single-crystal X-ray diffraction, whereas the remaining compounds have been studied by means of X-ray powder diffraction methods. Compounds 1,5 are isomorphous and crystallize in the triclinic space group P1 with unit cell parameters for 1 of a = 5.538(1) , b = 7.663(1) , c = 7.711(2) , , = 62.21(1), , = 73.91(1), , = 86.11(1), and Z = 1. The crystal structures are comprised of one-dimensional linear chains in which the trans -[M(4atr)2]2+ units are sequentially bridged by bis(bidentate) oxalato ligands, resulting in an octahedral O4N2 donor set. Cryomagnetic susceptibility measurements show the occurrence of antiferromagnetic intrachain interactions for 2, 3, and 5, whereas compound 1 exhibits a weak ferromagnetic coupling in agreement with the out-of-plane exchange pathway involved. The magnetic behavior of 1 and 2 is analyzed and discussed in the light of the available magneto-structural data for analogous systems. CdII complex crystallizes in the monoclinic space group C2/c with unit cell parameters of a = 16.128(2) , b = 6.757(1) , c = 11.580(2) , , = 104.46(1), and Z = 4. Its crystal structure contains one-dimensional chains in which metal centers are heptacoodinated to four oxygen atoms from two symmetry-related bis(bidentate) oxalato bridges, two endocyclic nitrogen atoms of trans -coordinated triazole ligands and one water molecule, to give a CdO4OwN2 pentagonal-bipyramidal geometry. Thermoanalytical and variable-temperature X-ray powder diffraction analyzes show that compound 6 undergoes a reversible dehydration,hydration process in which the anhydrous residue crystallizes with a different crystal lattice retaining the dimensionality of the oxalato,metal framework. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

On the Crystal Structure of Isotactic cis -1,4-Poly(1,3-pentadiene)

Roberto Napolitano
Abstract Summary: A comparison between the crystal structure of isotactic cis -1,4-poly(1,3-pentadiene) previously predicted by molecular mechanics calculations and that successively determined by other authors by experimental data is reported. The agreement between the two structures is very good as far as the space group, the unit cell parameters and the conformation of the polymer chain are concerned. The mode of packing of the chains proposed in the experimental crystal structure is very similar to that found as relative minimum in the previous energy calculations. The coexistence, in different amounts, of these two modes of packing is suggested by the analysis of the simulated X-ray spectra and by the results of new energy calculations. A mode of packing of chains of isotactic cis -1,4-poly(1,3-pentadiene). [source]

Investigation of structure and dynamics in the sodium metallocenes CpNa and CpNaTHF via solid-state NMR, X-ray diffraction and computational modelling

Cory M. Widdifield
Abstract Solid-state 23Na NMR spectra of two organometallic complexes, cyclopentadienylsodium (CpNa) and the tetrahydrofuran (THF) solvate of CpNa (CpNaTHF), are presented. Analytical simulations of experimental spectra and calculated 23Na electric-field gradient (EFG) tensors confirm that both complexes are present in microcrystalline samples of CpNa recrystallized from THF. For the solvate, 23Na NMR experiments at 9.4 T and 11.7 T elucidate sodium chemical shielding (CS) tensor parameters, and establish that the EFG and CS tensor frames are non-coincident. Single-crystal X-ray diffraction (XRD) experiments are used to determine the crystal structure of CpNaTHF: Cmca (a = 9.3242(15) , b = 20.611(3) , c = 9.8236(14) , , = , = , = 90 , V = 1887.9(5)3, Z = 8). For CpNa, 23Na NMR data acquired at multiple field strengths establish sodium CS tensor parameters more precisely than in previous reports. Variable-temperature (VT) powder XRD (pXRD) experiments determine the temperature dependence of the CpNa unit cell parameters. The combination of 23Na quadrupolar NMR parameters, pXRD data and calculations of 23Na EFG tensors is used to examine various models of dynamic motion in the solid state. It is proposed that the sodium atom in CpNa undergoes an anisotropic, temperature-dependent, low frequency motion within the ab crystallographic plane, in contrast with previous models. Copyright 2007 John Wiley & Sons, Ltd. [source]

Crystal structure of the new quaternary copper manganese and zirconium chalcogenides

V. P. Sachanyuk
Abstract The compounds Cu2MnZrS4 and Cu2MnZrSe4 were obtained by solid-state synthesis method. It was established using an XRD powder method that they crystallize in the hexagonal structural type (space group P3m1) with unit cell parameters a = 0.37427(2) nm, c = 0.61004(3) nm (Cu2MnZrS4); a = 0.39085(2) nm, c = 0.63709(3) nm (Cu2MnZrSe4). Atomic parameters were calculated using the anisotropic approximation (RI = 0.0523 and RI = 0.0473 for Cu2MnZrS4 and Cu2MnZrSe4, respectively). ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Structures of the OmpF porin crystallized in the presence of foscholine-12

Georgia Kefala
Abstract The endogenous Escherichia coli porin OmpF was crystallized as an accidental by-product of our efforts to express, purify, and crystallize the E. coli integral membrane protein KdpD in the presence of foscholine-12 (FC12). FC12 is widely used in membrane protein studies, but no crystal structure of a protein that was both purified and crystallized with this detergent has been reported in the Protein Data Bank. Crystallization screening for KdpD yielded two different crystals of contaminating protein OmpF. Here, we report two OmpF structures, the first membrane protein crystal structures for which extraction, purification, and crystallization were done exclusively with FC12. The first structure was refined in space group P21 with cell parameters a = 136.7 , b = 210.5 , c = 137 , and , = 100.5, and the resolution of 3.8 . The second structure was solved at the resolution of 4.4 and was refined in the P321 space group, with unit cell parameters a = 215.5 , b = 215.5 , c = 137.5 , and , = 120. Both crystal forms show novel crystal packing, in which the building block is a tetrahedral arrangement of four trimers. Additionally, we discuss the use of FC12 for membrane protein crystallization and structure determination, as well as the problem of the OmpF contamination for membrane proteins overexpressed in E. coli. [source]

New Type of Polymeric Chain Constructed by Exo-bidentate Binaphthol Derivative

Ya-Qiong Gong
Abstract The self-assembly of a racemic exo-bidentate ligand 2,2,-bis(4-pyridylmethyloxy)-1,1,-binaphthyl, namely Rac -L, with cadmium(II) salt gave rise to a new one-dimensional polymer, which has been characterized by single crystal X-ray diffraction analysis. The polymer crystallizes in a triclinic space group P -1 with unit cell parameters: a=0.6976(1) nm, b=1.30160(14) nm, c=1.71146(17) nm,,=105.141(3) ,,=94.263(5),,=100.405(4), V=1.4633(2) nm3, Z=2, C32H29CdCl2N2O4.5, M=696.88, Dc=1.584 g/cm3, F(000) =708, ,(Mo K,) =0.972 mm,1. The final R and wR are 0.0498 and 0.1282 for 5079 observed reflections with I,,(I). [source]

Channel-like crystal structure of cinchoninium L - O -phosphoserine salt dihydrate

CHIRALITY, Issue 6 2010
Aleksandra Wese, ucha-Birczy
Abstract Studies on the interactions between L - O - phosphoserine, as one of the simplest fragments of membrane components, and the Cinchona alkaloid cinchonine, in the crystalline state were performed. Cinchoninium L - O -phosposerine salt dihydrate (PhSerCin) crystallizes in a monoclinic crystal system, space group P21, with unit cell parameters: a = 8.45400(10) , b = 7.17100(10) , c = 20.7760(4) , , = 90, , = 98.7830(10), , = 90, Z = 2. The asymmetric unit consists of the cinchoninium cation linked by hydrogen bonds to a phosphoserine anion and two water molecules. Intermolecular hydrogen bonds connecting phosphoserine anions via water molecules form chains extended along the b axis. Two such chains symmetrically related by twofold screw axis create a "channel." On both sides of this channel cinchonine cations are attached by hydrogen bonds in which the atoms N1, O12, and water molecules participate. This arrangement mimics the system of bilayer biological membrane. Chirality 2010. 2009 Wiley-Liss, Inc. [source]