Growth, spectral, dielectric and antimicrobial studies on 4-piperidinium carboxylamide picrate crystals.

Single crystal of 4-piperidinium carboxylamide picrate was grown by slow evaporation solution growth technique at ambient temperature. The average dimensions of grown crystal were 0.7×0.3×0.2 cm(3). The solubility of the compound was analyzed using methanol and acetone. Optical property of the compound was ascertained by UV-visible absorption spectral study. The sharp and well defined Bragg peaks observed in the powder X-ray diffraction pattern confirm its crystallinity. The different kinds of protons and carbons in the compound were confirmed by (1)H and (13)C NMR spectral analyses. The presence of various functional groups in the compound was assigned through polarized Raman spectral study. The mechanical property of the crystal was measured by Vicker's microhardness test and the compound was found to be soft material. The dielectric constant and dielectric loss of the crystal decrease with increase in frequency. The antibacterial and antifungal activities of the crystal were studied by disc diffusion method and found that the compound shows good inhibition efficiency against various bacteria and fungi species.

Structure and spectral properties of L-histidinium dipicrate dihydrate.

Non-linear optical active L-histidinium dipicrate dihydrate (LHDD) single crystals were grown by slow evaporation method. The Fourier transform FT-IR, FT-Raman, (1)H and (13)C NMR spectra of the crystal have been recorded and analysed. The spectral analyses confirm the formation of the compound and the stoichiometry. The geometry and spectral characteristics were examined using the density functional theory (DFT) method, B3LYP with 6-31G(d,p) basis set. The first-order hyperpolarisability, energies of frontier molecular orbitals and the Mulliken population analysis were also calculated. The HOMO-LUMO energy gap value 2.73 eV indicates the charge transfer from picrate to histidinium through the hydrogen bond. The second-order NLO properties of the molecule are studied by Kurtz-Perry powder technique. SHG efficiency of the compound is nearly 2.5 times greater than KDP. Theoretical calculations indicate hyperpolarisability of LHDD is 39 times greater than urea. The results show that the title molecule can be used for opto-electronic applications.

N (2)-(4-Meth-oxy-salicyl-idene)arginine hemihydrate.

The title compound, C14H20N4O4·0.5H2O [systematic name: (2S)-5-{[amino-(iminium-yl)meth-yl]amino}-2-{[(1Z)-4-meth-oxy-2-oxido-benzyl-idene]aza-nium-yl}penta-noate hemihydrate], has been synthesized by the reaction of l-arginine and 4-meth-oxy-salicyl-aldehyde and crystallizes with two independent substituted l-arginine mol-ecules and one water mol-ecule of solvation in the asymmetric unit. Each mol-ecule exists as a zwitterion and adopts a Z configuration about the central C=N. The mol-ecular conformation is stabilized by strong intra-molecular N-H⋯O hydrogen bonds that generate S(6) and S(10) ring motifs. Inter-molecular N-H⋯O and O-H⋯O hydrogen bonds involving also the water mol-ecule and weak inter-molecular C-H⋯Owater inter-actions link the mol-ecules into an infinite one-dimensional ribbon structure extending along the b axis. The known (2S) absolute configuration for l-arginine was invoked. Weak intermolecular C-H⋯π interactions are also present.

l-Histidinium dipicrate dihydrate.

In the title mol-ecular salt, C6H11N3O2 (2+)·2C6H2N3O7 (-)·2H2O, the histidine mol-ecule exists as a histidinium dication, being protonated at the N atom of the imidazole ring. The charges are balanced by two picrate anions and the compound crystallizes as a dihydrate. In the crystal, the components are linked via N-H⋯O and O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions, forming a three-dimensional supermolecular structure.