Thermodynamic Studies of Rare Earth Metal Complexes with Metformin Hydrochloride Drug in Mixed Solvent System

Abstract

In the present work we investigate the stability constant of Metformin Hydrochloride drug with rare earth (Lanthanides) metal ions La(III),Ce(III),Nd(III),Sm(III),Gd(III),Tb(III) and Dy(III) using pH metric technique in 20%(v/v) ethanol-water mixture at 298K, 308K, 318K and at an ionic strength of 0.1M NaClO4. The method of Calvin and Bjerrum as adopted by Irving and Rossotti has been employed to determine metal-ligand stability constant (logK) values. It is observed that rare earth (Lanthanide) metal ions forms 1:1 and 1:2 complexes.The thermodynamic parameter ΔG, ΔH and ΔS were calculated from values of stability constant at different temperatures. The formations of metal complexes were found to be spontaneous and exothermic in nature.