An-Najah Blogs :: An-Najah Blogs :: en-us Wed, 21 Oct 2020 23:37:25 IST Wed, 21 Oct 2020 23:37:25 IST Crystal and molecular structure of imidazole derivatives with different substituents ArticlesThe crystal and molecular structures of 1-Methyl-2-Isopropyl-5-Nitroimidazole A and 1-Methyl-2Thiophenyl-Methyl-5-Nitroimidazole B derivatives were determined by X-ray diffraction methods The compound A C7H11N3O2 crystallises in the monoclinic space group P21c with a = 995822 Angstrom b = 652404 Angstrom c = 1355603 Angstrom beta = 99893017degrees V = 86765 Angstrom3 Z = 4 D-calc = 1295 Mgm3 mu = 0813 mm-1 F-000 = 360 CuK alpha = 15406 Angstrom and R = 009 The five membered ring with two nitrogen atoms is planar Layering is observed down a and b axes The compound B C11H11N3O2S crystallises in the triclinic space group P 1 over bar with a = 627010 Angstrom b = 2787412 Angstrom c = 129603 Angstrom alpha = 90 degrees beta = 8990 degrees gamma = 90 degrees V = 226635 Angstrom3 Z = 8 D-calc = 1461 Mgm3 mu = 2504 mm-1 F-000 = 1040 CuK alpha = 15406 Angstrom and R = 011Crystal Structure of Diphenyl Pyraline Hydrochloride-Cobalt Chloride Complex ArticlesThe crystal structure of the complex of diphenyl pyraline hydrochloride with cobalt chloride C38H46O2N2Cl4Co has been determined by X-ray diffraction using CuK radiation The compound crystallizes in monoclinic space group P21n with the cell parameters a = 181204 b = 81793 c = 268053 = 102601 with Z = 4 V = 387613 The structure was solved using 5484 reflections The stucture was refined to a final wR of 02944 R = 01130 The packing of the molecules shows a layered arrangementCrystal-Structure of Bis(Lignocainium) Tetrathiocyanatocobaltate(II) Hydrate, (C14h22on2)2co(Ncs)4(H2o) ArticlesZeitschrift Fur Kristallographie Volume: 209 Issue: 11 Pages: 918-919 Published: 1994Crystal-Structure of Bis(Lignocainium) Tetrabromocuprate(II), (C14h22on2)2cubr4 ArticlesZeitschrift Fur Kristallographie Volume: 209 Issue: 11 Pages: 920-921 Published: 1994Crystal-Structure of Lignocaine Tetrachloroferrate(III) Complex ArticlesZeitschrift Fur Kristallographie Volume: 203 Pages: 161-166 Part: Part 2 Published: 1993Infrared and Far Infrared Studies on the Nematic Compounds Exhibiting Re-Entrant Systems ArticlesActa Physica Polonica A Volume: 74 Issue: 6 Pages: 735-742 Published: Dec 1988Optical and DSC Studies on Pure Nematogenic Materials Exhibiting Reentrant Isotropic-Phase ArticlesOptical and DSC Studies on Pure Nematogenic Materials Exhibiting Reentrant Isotropic-PhaseCrystal-Structure of Nematogenic 4,4'-Bis(Pentyloxy) Azoxy Benzene ArticlesZeitschrift Fur Kristallographie Volume: 172 Issue: 1-2 Pages: 79-87 Published: 1985Infrared and Far-Infrared Studies on the Nematogenic Homologous Series Trans-4-Alkyl-(4-Cyanophenyl) Cyclohexanes ArticlesInfrared 4000-650 cm-1 and far-infrared 650-20 cm-1 spectra of the nematogenic homologous series trans-4-alkyl-4-cyanophenyl cyclohexanes ethyl propyl butyl pentyl and heptyl have been examined in the solid and liquid crystalline states An attempt has been made to correlate the variation in the intensities and frequency shifts with the molecular structures The gradual shift towards smaller wavelength in the CN stretching vibration and the relative alternation in the intensity of this frequency as the chain length increases may be correlated with odd-even effects in homologous liquid crystals and with the increase in thermal stability as the spectra reveal an increase in the dipole-dipole interaction between the neighbouring molecules A strong feature centred around 90 cm-1 is assigned to hindered rotation about the long axis of the molecule Absolute orientational order parameter S has been evaluated for the series by a study of the temperature variation of CN vibration in homeotropically oriented sample The results are in very good conformity with those of NMR and optical methodsCrystal-Structure of Mesogenic Material Iv-Nematogenic 4-(4'-Ethoxyphenylazo)Phenyl Heptanoate ArticlesZeitschrift Fur Kristallographie Volume: 169 Issue: 1-4 Pages: 109-115 Published: 1984Crystal Structure of Mesogenic Material III Nematogenic 4-(4'-EthoxyphenyIazo)PhenyI Undecylenate ArticlesThe crystal structure of 4-4-ethoxyphenylazophenyl undecylenate has been determined by direct methods The compound crystallizes in space group P21n with a = 59141 b = 151433 c = 258192A and = 914502 The structure was refined to R = 00412 for 1998 observed reflections The molecule is almost linear and planar The angle between the two phenyl rings is 3996 The pairs of molecules related by a centre of symmetry form an imbricated arrangementOrientational order parameters of nematogenic trans-4-propyl cyclohexyl-4 (trans-4-alkyl cyclohexyl) benzoates ArticlesThe refractive indices and densities of three members of trans-4-propyl cyclohexyl-4 trans-4-alkyl cyclohexyl benzoates are reported as functions of temperature in the nematic and isotropic phases The principal molecular polarizabilities and order parameters S have been evaluated using the anisotropic internal field model Neugebauers approach Also order parameters have been estimated by studying the dipole-dipole splittings in the wide line proton magnetic resonance PMR spectra The results obtained are in close agreement with those obtained from refractive index measurementsRefractive Indices, Densities, Polarizabilities and Molecular Order in Cholesteric Liquid Crystals ArticlesThe temperature variation of refractive indices none birefringence n density and order parameter S of two cholesteric liquid crystalscholesteryl benzoate and laurate are reported in the smectic cholesteric and isotropic phases The order parameters have been evaluated using Averyanovs relations The S values determined are good agreement with NMR data The mean polarizabilities of a few cholesteric liquid crystals have been evaluated using i the modified method of Lippincott--function potential model and ii the additivity rule of bond polarizabilities There is good agreement between the values of calculated by these methods and experimental values thereby suggesting the general applicability of Lippincott--function potential model to liquid crystalsUnit-Cell Dimensions and Space Group Of Trans-4-Propyl Cyclohexyl-4-(Trans-4-Ethyl Cyclohexyl) Benzoate and Trans-4-Propyl Cyclohexyl-4-(Trans-4-Propyl Cyclohexyl) Benzoate ArticlesZeitschrift Fur Kristallographie Volume: 158 Issue: 3-4 Pages: 313-314 Published: 1982Unit cell dimensions and space groups of some liquid crystals ArticlesIt is now very well established that for a proper understanding and interpretation of several physical properties of liquid crystalline phases a knowledge of the molecular structure in the crystalline state is very useful as the molecular conformation in the crystalline state predetermines the molecular organisation inthe mesomorphic state Also it is believed that the stabilisation of liquid crystalline phase and hence the micro variations in the physical properties depend strongly on the long side chains and are essentially independent of the central rigid core In view of this we communicate the preliminary crystallogrphic data for some liquid crystalline materials the detailed structure of which has been taken upOrientational order in the nematogenic homologous series trans-4-alkyl (4-cyanophenyl)-cyclohexane ArticlesThe temperature variation of refractive indices neno birefringence n density and order parameter of the homologous compounds trans-4-alkyl 4-cyanophenyl-cyclohexane are reported in the nematic and isotropic phases The principal molecular polarizabilities eo and the order parameters S have been evaluated using the anisotropic internal field model Neugebauers approach The theoretical estimations of the mean and principal molecular polarizabilities made by two different approaches viz the additivity rule of bond polarizability and the modified Lippincott--function potential model are in close agreement with the values evaluated from the experimental studies The Journal of Chemical Physics is copyrighted by The American Institute of PhysicsNuclear magnetic resonance spectroscopy studies of nematic liquid crystals. 2. trans-4-Alkyl(4-cyanophenyl)cyclohexanes ArticlesNMR has been employed to measure the orientational order parameters for the nematogenic homologous series trans-4-alkyl4-cyanophenylcyclohexanes by studying the dipole-dipole splittings The values of the order parameters are compared with those obtained by optical studies