Synthesis, Spectroscopic and Pharmacological Studies of Bivalent Copper, Zinc and Mercury Complexes of Thiourea

Abstract

A series of metal complexes of Cu(II), Zn(II) and Hg(II) having the general composition [M(L)₂X₂] [where L = thiourea; M=Cu(II), Zn(II) or Hg(II) andX=Cl^–,NO3^– orCH3COO^–] have been synthesized. All the metal complexes were characterized by elemental chemical analysis, molar conductance, magnetic susceptibility measurements and IR spectroscopy. Cu(II) complexes were additionally characterized by electronic and EPR spectral studies. The IR spectral data suggests the involvement of sulphur atom in coordination to the central metal ion. On the basis of spectral studies square planar geometry has been assigned to Cu(II) complexes except [Cu(L)₂(CH₃COO^–)₂] which exhibits six coordinated tetragonal geometry. However, all Zn(II) and Hg(II) complexes exhibited tetrahedral geometry. Furthermore, to achieve a better pharmacological profile, thiourea and its metal complexes were screened for in vitro antimicrobial activity against the human pathogenic bacteria Staphylococcus aureus, Staphylococcus epidermides, Escherichia coli and Pseudomonas aeruginosa and against the fungi Candida albicans and Aspergillus niger. Thiourea and its metal complexes were also screened for in vivo anti-inflammatory activity. Thiourea did not exhibit antibacterial activity but showed antifungal activity. However, it is important to note that the Cu(II), Zn(II) and Hg(II) complexes of thiourea exhibited antibacterial and enhanced antifungal activity. Neither thiourea nor its metal complexes exhibited anti-inflammatory activity.

Keywords: Thiourea Complexes, Spectroscopy, Antibacterial Activity, Antifungal Activity, Anti-inflammatory Activity