Synthesis, spectroscopic, and thermal investigation of transition and non-transition complexes of metformin as potential insulin-mimetic agents

Abstract

Complexes of [Mn(MF)2(Cl)2]·2H2O (1), [Fe(MF)2(Cl)2]Cl·4H2O (2), [Ni(MF·HCl)2(Cl)2]·6H2O (3), [Cu(MF·HCl)2(Cl)2] (4), [Zn(MF·HCl)2](NO3)2·6H2O (5), [Cd2(MF·HCl)(Cl)4(H2O)] (6), [Mg(MF·HCl)2(Cl)2]·6H2O (7), [Sr2(MF·HCl)(Cl)4(H2O)] (8), [Ba(MF·HCl)2(Cl)2]·2H2O (9), [Pt(MF)4] (10), [Au(MF)3]Cl3 (11), and [Pd(MF)2]Cl2 (12) were synthesized from Legitional behavior of metformin drug as a diabetic agent. The authenticity of the transition and non-transition metal complexes were characterized by elemental analyses, molar conductivity, (infrared, UV–Vis) spectra, effective magnetic moment in Bohr magnetons, electron spin resonance, thermal analysis, X-ray powder diffraction as well as scanning electron microscopy. Infrared spectral studies as well as elemental analyses revealed the existence of metformin in the base or hydrochloride salt forms in the chelation state acts as a bidentate ligand while the platinum(IV) complex is coordinated through the deprotonation of –NH group. The magnetic and electronic spectra of Mn(II), Fe(III), Ni(II), and Cu(II) complexes suggest an octahedral geometry. Antimicrobial screening of metformin and its complexes were determined against the (G+ and G−) bacteria (Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Pseudomonas aeruginosa) and fungi (Aspergillus flavus and Candida albicans).