Spectral and Structural Characterization of Metformin with Different Counter Anions: Comparative Analysis and DFT Calculations

Abstract

The metformin perchlorate (MetH+·ClO4 −) with a new crystal structure was synthesized, characterized and comparatively studied with other metformin salts of Cl− and NO3 − by different spectroscopic techniques such as TGA-DSC and FT-IR as well as UV-visible spectroscopic studies. DFT calculations were performed by rwb97xd and 6-31G+(d,p) basis set for structure optimization and frequency calculations. Similar to MetH+·Cl−, the crystal packing of MetH+·ClO4 −andMetH+·NO3 − were stabilized by hexagonal hydrogen bond elongated network. The relative stability and reactivity of these salts were determined by exploring the DFT chemical descriptors such as chemical hardness, electronegativity, electronic chemical potential, electrophilicity and hardness. These calculations were employed to get the subset of variables that could categorize the metformin salts according to their reactivity.