Synthesis, characterization and biological activity of N- thioureidophthalimic acid and its divalent transition metal complexes

Abstract

The thiosemicarbazide derivative, N-thioureidophthalimic acid and its complexes with Zn(II), Cu(II), Co(II), Ni(II) and Pd(II) ions have been prepared and characterized by elemental analysis, molar conductivity, thermal analysis, spectroscopy (I.R, U.V. VIS., 1H NMR, mass spectrometry) and magnetic susceptibility measurements. The thiosemicarbazide derivative coordinates to the metal ions as a mononegative tridentate ligand or a mononegative bidentate ligand. The free ligand and its metal complexes have been tested in vitro against a number of microorganisms, to assess their antimicrobial properties. Antimicrobial screening of the ligand and its complexes against Aspergillus, flavus and Candida albicans (fungi); Esherichia Coli (G-) and Staphilococcus aureus (G+) (bacteria). The ligand and its complexes exhibit higher activity against bacteria than fungi. The experimental results show that nearly all complexes exhibit antibacterial activity higher than the free ligand but less than the standard. In general the studied compounds are thermally stable. The TGA of the complexes revealed loss of water of hydration molecules in the first step followed by decomposition of the ligand in subsequent steps