Nidhi Tyagi

Performance of crystal violet doped triglycine sulfate single crystals for optical and communication applications

Single crystals of 0.01 and 0.02 mol% crystal violet dye doped triglycine sulfate (NH2CH2COOH)3·H2SO4 (TGS) have been grown by a slow evaporation technique. Enhanced dielectric, optical, thermal and mechanical properties have been achieved by dye doping. Monoclinic structures showing particular coloring patterns and morphology change with dye concentration were obtained. Various functional groups and dye incorporation in the grown crystals were confirmed qualitatively by FTIR and Raman analysis. A significant increase in Curie temperature from 50 to 55 °C with a decrease in maximum permittivity has been observed. The UV-vis spectra showed an increased transmittance window and an increased optical band gap from 5.61 to 6.11 eV as a result of doping. An increase in the sharpness and intensity of the photoluminescence peak with a blue shift has been observed in doped crystals. The thermal stability and the decomposition temperature were found to increase by about 10 °C in 0.01 mol% dye doped TGS. The mechanical strength of the grown crystals was estimated by the Vickers microhardness test and was found to be high for dye doped TGS. A high piezoelectric charge coefficient d33 of 16 pC N−1 was observed for pure TGS which decreased as a result of the dye effect. The fabrication of a patch antenna was carried out after simulating its resonant frequency, making it suitable for telecommunication applications.

Growth, crystal structure, Hirshfeld surface, dielectric and mechanical properties of a new organic single crystal: ‘Bis glycine’ squarate

A novel transparent organic crystal ‘Bis glycine’ squarate has been grown by a slow evaporation method. Single crystal XRD confirms the monoclinic lattice with space group C2/c in BGSQ crystal with a refinement value (R) of 0.06. The molecular electron charge density distribution of the BGSQ compound is described. The growth rate of the BGSQ crystal is estimated by morphological study. The Hirshfeld surface gives information about intermolecular interactions within the crystal structure and the fingerprint plot shows the nature and type of intermolecular close contact experienced by the molecules in a crystal. The FTIR spectrum confirms the various functional groups present in the grown crystal. Thermal stability and melting point (182.20 °C) were studied with TGA-DTA. The low value of the dielectric constant of BGSQ suggests that the crystal can be used in the microelectronics industry. In UV spectra, a lower cutoff value at 280 nm and a wide band gap of 4.25 eV for the BGSQ crystal are observed. Meyers index number (1.817) in hardness studies confirmed the soft nature of the crystals. Voids have been used to describe the mechanical strength of crystalline materials.

Copper(II) complexes of a new tetradentate bis-benzimidazolyl diamide ligand with disulfanediyl linker: synthesis, characterization, and oxidation of some pyridyl, napthyl, and benzyl alcohols

The bis-benzimidazolyl diamide ligand 3,3′-disulfanediyl-bis-(N-((1H-benzo[d]imidazol-2-yl)methyl)propanamide) (L) having N, S, and O donors has been synthesized and utilized to prepare copper(II) complexes of general composition [Cu(L)X]·X·nH2O, where X is Cl– or . Ligands and complexes were characterized by elemental analysis, UV–visible, IR spectroscopy, 1H NMR, mass spectrometry, conductance, electron paramagnetic resonance, cyclic voltammetry, fluorescence, single-crystal, and PXRD. [Cu(L)(NO3)]NO3·H2O crystallizes in the monoclinic C2/c space group with one molecule in the asymmetric unit. Copper adopts a distorted octahedral geometry with four coordination sites occupied by the ligand and two sites by a bidentate nitrate. [Cu(L)(NO3)]NO3·H2O has been utilized as a catalyst to oxidize alcohols with tert-butyl hydroperoxide as an alternative source of oxygen. The oxidized products have been characterized by GCMS.

Growth, morphology, structure and characterization of L-histidinium dihydrogen arsenate orthoarsenic acid single crystal.

L-Histidinium dihydrogen arsenate orthoarsenic acid (LHAS) crystals were grown by the slow evaporation method. Single-crystal X-ray diffraction confirms monoclinic structure. The growth rates of various planes of LHAS crystals were estimated by morphological study. Hirshfeld surface and fingerprint plots were analyzed to investigate the intermolecular interactions at 0.002 a.u. present in the crystal structure. The functional groups and phase behavior of the compound are studied by FTIR spectroscopy and differential scanning calorimetry (DSC). A ferroelectric to paraelectric phase transition at 307 K was observed in dielectric studies. The piezoelectric charge coefficients of the grown crystal were found to be 2 pC/N. The values of coercive field (Ec), remnant polarization (Pr) and spontaneous polarization (Ps) in the hysteresis loop are found to be 5.236 kV cm(-1), 0.654 µC cm(-2) and 2.841 µC cm(-2), respectively. Piezoelectricity and ferroelectricity are reported for the first time in LHAS crystals. The mechanical strength was confirmed from microhardness study and void volume. Due to the low value of the dielectric constant, and good piezoelectric and ferroelectric properties, LHAS crystals can be used in microelectronics, sensors and advanced electronic devices.

Iron(III) complexes of bis (benzimidazol-2-yl) methyl) thiophene-2,5-dicarboxamide: synthesis, spectral and oxidation of o-phenylenediamine.

Iron(III) complexes of a potentially pentadentate ligand N(2), N(5)-bis ((1H-benzo [d] imidazol-2-yl) methyl) thiophene-2,5-dicarboxamide are synthesized with an exogenous anion X=Cl(-), NO(3)(-). Mössbauer and EPR spectroscopy indicates axially distorted complexes. These complexes were utilized for the oxidation of o-phenylenediamine to 2,3-diaminophenazine in presence of H(2)O(2). The initial rate of reaction is dependent on the concentration of o-phenylenediamine as well as the iron(III) complex. Rates of reaction were found to be at least five times higher for the Cl(-) bound complex. The effect of an added anion like acetate, azide and citrate is found to inhibit the rate of reaction. This suggests that one of the factors affecting the rate determining step is the binding of these anions on a vacant site at the iron(III) centre. The oxidation of o-phenylenediamine to 2,3-diaminophenazine is reminiscent of the functioning of horse radish peroxidase.