Metal complexes of omeprazole. Preparation, spectroscopic and thermal characterization and biological activity

Metal complexes of omeprazole (OPZ) are prepared and characterized based on elemental analyses, IR, diffuse reflectance, magnetic moment, molar conductance and thermal analyses (TGA and DTA) techniques. From the elemental analyses, the complexes have the general formula [M(L)2]Xn [where M = Cr(III) (X = Cl, n = 3), Ni(II) (X = ClO4, n = 2) and Zn(II) (X = Cl, n = 2)], and [M(L)2(H2O)2]Xn yH2O (where M = Fe(III) (X = Cl, n = 3, y = 0), Co(II) (X = Cl or ClO4, n = 2, y = 0-4) and Ni(II) (X = Cl, n = 2, y = 4) and [Cu(L)2]Cl2 H2O. The molar conductance data reveal that all the metal chelates are 3 : 1 electrolytes (for Cr(III) and Fe(III) complexes) and 2 : 1 (for the remaining complexes). IR spectra show that OPZ coordinates to the metal ions as neutral bidentate with ON donor sites of the pyridine-N and sulphone-O. The magnetic and solid reflectance spectra indicate octahedral (FeCl3, CoCl2, CoClO4 and NiCl2), square planar [Cu(II)] and tetrahedral [Mn(II), Cr(III), NiClO4 and Zn(II)] structures. The thermal behavior of these chelates using thermogravimetric and differential thermal analyses (TGA and DTA) techniques indicate the hydrated complexes lose water of hydration followed immediately by decomposition of the anions and ligand molecules in the successive overlapping OPZ and its metal complexes are screened for antibacterial activity against Escherichia coli, Staphylococcus aureus, Aspergillus flavus and fungi (Candida albicans). The activity data show the metal complexes to be more potent/antibacterial than the parent OPZ ligand against one or more bacterial species.