Synthesis, growth, structure and characterization of a new semiorganic crystal: Tetrakis(thiourea)zinc(II) picrate

Single crystals of tetrakis(thiourea)zinc(II) picrate (TTZP) have been grown by slow evaporation of a mixed solvent system water-acetone containing thiourea, zinc chloride and picric acid. Crystal composition determined by single crystal X-ray diffraction analysis reveals that it belongs to the triclinic system with space group Pi and the cell parameters are, a=6.8333(5) angstrom, b=12.6011(1) angstrom, c=18.3423(14) angstrom, alpha=90.02 degrees, beta=99.977 degrees, gamma=100.71 degrees, V=1527.5(2) angstrom(3) and Z=2. The zinc metal is coordinated by four thiourea groups with Zn-S-C bond angles ranging from 108.65 degrees to 113.55 degrees and Zn-S bond lengths lying in the range 2.320 to 2.327 angstrom in a distorted tetragonal geometry. The crystal contains Zn(tu)(4)(2+) cations and stacks of picrate ions. Higher transmittance in the visible region is observed with a lower optical cut-off at similar to 290 nm. The diffuse reflectance spectroscopy (DRS) was employed to estimate the band gap energy. The vibrational patterns in FT-IR are used for identifying the material and the thermal analysis by TG/DTG indicates the stability. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.