Sp. Meenakshisundaram

Crystal growth, structure and characterization of o-hydroxybenzoic acid single crystals

Single crystals of o-hydroxybenzoic acid (o-HBA, salicylic acid) have been grown by slow evaporation solution growth technique. It crystallizes in monoclinic system with two molecular units in the cell (centrosymmetric space group P21/c). The lattice parameters are axa0=xa04.8967(6)xa0Å, bxa0=xa011.2204(14)xa0Å, cxa0=xa011.3027(15)xa0Å and βxa0=xa092.096(12)°. The modes of vibrations of different functional groups present were identified by FT-IR studies. Differential scanning calorimetry (DSC) study reveals the purity of the sample and no decomposition is observed up to the melting point. The crystals are further characterized using UV–Vis and powder XRD. Effect of solvents on the growth and morphology has been investigated. The crystalline cohesion is achieved by intra and intermolecular hydrogen bonds.

Optical, thermal and dielectric properties of Sr(II)-doped bis(thiourea)zinc(II) chloride crystals

The influence of strontium doping on the properties of bis(thiourea)zinc(II) chloride (BTZC) crystals has been described. The reduction in the intensity observed in powder X-ray diffraction of doped specimen and slight shifts in vibrational frequencies confirm the lattice stress as a result of doping. The incorporation of Sr(II) into the crystal lattice was confirmed by energy dispersive X-ray spectroscopy (EDS). Surface morphological changes due to doping of the alkaline earth metal are observed by scanning electron microscopy (SEM). The crystal is transparent in the entire visible region having a lower optical cut-off at ~308 nm with a band gap energy of 4.06 eV. The DSC studies reveal the purity of the materials and no decomposition is observed up to the melting point. Dielectric studies show that the isovalent ion Sr(II)-doping altered the dielectric properties of the host crystal.

Growth, crystalline perfection, spectral, thermal and theoretical studies on imidazolium L-tartrate crystals.

Transparent optical quality single crystals of imidazolium L-tartrate (IMLT) were grown by conventional slow evaporation solution growth technique. Crystal structure of the as-grown IMLT was determined by single crystal X-ray diffraction analysis. Thermal analysis reveals the purity of the crystal and the sample is stable up to the melting point. Good transmittance in the visible region is observed and the band gap energy is estimated using diffuse reflectance data by the application of Kubelka-Munk algorithm. The powder X-ray diffraction study reveals the crystallinity of the as-grown crystal and it is compared with that of the experimental one. An additional peak in high resolution X-ray diffraction (HRXRD) indicates the presence of an internal structural low angle boundary. Second harmonic generation (SHG) activity of IMLT is significant as estimated by Kurtz and Perry powder technique. HOMO-LUMO energies and first-order molecular hyperpolarizability of IMLT have been evaluated using density functional theory (DFT) employing B3LYP functional and 6-31G(d,p) basis set. The optimized geometry closely resembles the ORTEP. The vibrational patterns present in the molecule are confirmed by FT-IR coinciding with theoretical patterns.

Synthesis, structure, spectral, thermal and first-order molecular hyperpolarizability of 4-benzoylpyridine isonicotinyl hydrazone monohydrate single crystals.

Single crystals of 4-benzoylpyridine isonicotinyl hydrazone monohydrate were grown by slow evaporation solution growth technique from ethanol at room temperature. It belongs to triclinic system with space group P1¯ and the cell parameters are, a=8.9250(2) Å, b=9.1540(2) Å, c=10.87500(10) Å and V=797.88(3) Å(3). Powder XRD closely resembles with that of simulated pattern from single crystal XRD. The characteristic functional groups present in the molecule are confirmed by FT-IR and FT-Raman analyses. The crystal is transparent in the visible region having a lower optical cut-off at ∼420 nm and the band gap energies are estimated by the application of Kubelka-Munk algorithm. Thermal analysis by TG/DTA indicates the stability of the material. The scanning electron microscopy studies reveal the surface morphology of the as-grown crystal. Mass spectrometry provides information pertaining to the structure and molecular weight of the compound. Theoretical calculations were performed using Hartree-Fock method with 6-31G(d,p) as the basis set for to derive the optimized geometry, dipole moment and first-order molecular hyperpolarizality (β) values.

Growth and characterization of 2-amino-5-nitrobenzophenonium picrate crystals

Single crystals of 2-amino-5-nitrobenzophenonium picrate (ANBP) were grown by slow evaporation solution growth technique from a mixed solvent system ethanol–chloroform–acetic acid (1:1:1, v/v). The 1H and 13C signals of the grown crystal are identified by the nuclear magnetic resonance analyses. Fourier transformed infrared spectroscopy confirms the presence of characteristic functional groups present in the grown crystal. Powder X-ray diffraction was carried out to determine the structure and crystallinity. The crystal belongs to monoclinic system. The optical properties of the grown crystals were analyzed by UV–Vis spectroscopy. Thermogravimetric and differential thermal analysis studies reveal no decomposition up to the melting point. The surface morphology of the as-grown crystals was studied by scanning electron microscopy.

Synthesis, spectral, thermal, optical and theoretical studies of (2E,6E)-2-benzylidene-6-(4-methoxybenzylidene)cyclohexanone

Single crystals of (2E,6E)-2-benzylidine-6-(4-methoxybenzylidine)cyclohexanone are grown by slow evaporation of ethanolic solution at room temperature. The characteristic functional groups present in the molecule are confirmed by Fourier transform infrared and Fourier transform Raman analyses. The scanning electron microscopy study reveals the surface morphology of the material. Thermogravimetric/differential thermal analysis study reveals the purity of the material and the crystal is transparent in the visible region having a lower optical cut-off at ∼487nm. The second harmonic generation efficiency of as-grown material is estimated by Kurtz and Perry technique. Optimized geometry has been derived using Hartree-Fock calculations performed at the level 6-31G (d,p) and the first-order molecular hyperpolarizability (β) is estimated. The specimen is further characterized by nuclear magnetic resonance spectroscopy.

Growth, structure, and characterization of tris(thiourea)silver(I) nitrate

Single crystals of tris(thiourea)silver(I) nitrate have been grown by slow evaporation solution growth technique from an aqueous solution at 25xa0°C. The single crystal X-ray diffraction study reveals that the crystal belongs to tetragonal system and cell parameters are axa0=xa0bxa0=xa014.2790(4)xa0Å, cxa0=xa024.8900(7)xa0Å, and Vxa0=xa05074.8(2)xa0Å3. The various functional groups present in the molecule are confirmed by Fourier transformed infrared spectroscopy (FT-IR). The structure and the crystallinity of the materials were further confirmed by powder X-ray diffraction analysis. Thermogravimetric and differential thermal analysis reveal the purity of the sample and no decomposition is observed up to the melting point. The crystal is further characterized by UV–Vis and Vickers microhardness analysis.

Crystal growth, characterization and theoretical studies of alkaline earth metal-doped tetrakis(thiourea)nickel(II) chloride.

The influence of Sr(II)-doping on the properties of tetrakis(thiourea)nickel(II) chloride (TTNC) has been described. The reduction in the intensity observed in powder X-ray diffraction of doped specimen and slight shifts in vibrational frequencies of doped specimens confirm the lattice stress as a result of doping. Surface morphological changes due to doping of the Sr(II) are observed by scanning electron microscopy. The incorporation of metal into the host crystal lattice was confirmed by energy dispersive X-ray spectroscopy. Lattice parameters are determined by single crystal XRD analysis. The thermogravimetric and differential thermal analysis studies reveal the purity of the materials and no decomposition is observed up to the melting point. The nonlinear optical properties of the doped and undoped specimens were studied. Theoretical calculations were performed using the Density functional theory (DFT) method with B3LYP/LANL2DZ as the basis set. The molecular geometry and vibrational frequencies of TTNC in the ground state were calculated and the observed structural parameters of TTNC are compared with parameters obtained from single crystal X-ray studies. The atomic charge distributions are obtained by Mulliken charge population analysis. The first-order molecular hyperpolarizability, polarizability and dipole moment were derived.

Synthesis, structure, characterization and theoretical studies of NLO active furan-2-carbohydrazide monohydrate derivative single crystals

Single crystals of (E)-N′-(4-isopropylbenzylidene)furan-2-carbohydrazide monohydrate were grown by the slow evaporation solution growth technique from ethanol at room temperature. The crystals belong to the orthorhombic system with noncentrosymmetric space group P212121. The crystallinity of the material was confirmed by powder X-ray diffraction analysis. The functional groups present in the molecule are identified by FT-IR analysis and the band gap energy is estimated using diffuse reflectance data by the application of Kubelka–Munk algorithm. Theoretical calculations were performed using a density functional theory (DFT) method to derive the optimized geometry, dipole moment, polarizability, HOMO–LUMO energies at different levels, molecular electrostatic potential, excited state energy, oscillator strength, Mulliken charge population and first-order molecular hyperpolarizability, (β) (>58 times of urea). The intermolecular hydrogen bonding interactions are analyzed by Hirshfeld surface analysis and fingerprint plots. The second harmonic generation efficiency (SHG) is estimated using the Kurtz and Perry powder technique and it reveals NLO (nonlinear optical) character. As-grown crystals were further characterized by NMR, mass spectrometry and elemental analysis.

Co(II), Co(II)+Mn(II), Co(II)+Ni(II) Co-doping Effects on Tris(thiourea)zinc(II) Sulphate Crystals: A Comparative Study

The influence of Co(II), Co(II)+Mn(II), Co(II)+Ni(II) co-doping on the structure and crystalline perfection of tris(thiourea)zinc(II) sulphate single crystals grown from an aqueous solution at room temperature by slow evaporation solution growth technique has been investigated. The incorporation of foreign metal into the crystalline lattice was well confirmed by chemical formula determined by single-crystal X-ray diffraction analysis. The intensity variations observed in powder X-ray diffraction patterns and slight shifts in vibrational frequencies in Fourier transform IR indicate the lattice stress. Thermal studies reveal the purity of the material and no decomposition is observed up to the melting point. High-resolution X-ray diffraction studies reveal that Co(II)-doped specimen has no clustering of defects while the Co(II)+Mn(II), Co(II)+Ni(II) co-doped crystals show the presence of structural grain boundaries as a result of crystal stress and strain. The as-grown crystals are further characterized by Kurtz powder technique and dielectric studies. Good transparency in the visible region is observed for all the specimens. Interestingly, in co-doping the host crystal selectively accommodates only one foreign metal ion as revealed by single-crystal XRD analysis.