pH Metric Study of Schiff Base Metal Complexes of Dysprosium (III) in 80 %( V/V) Ethanol-Water Mixture

The proton-ligand and metal-ligand stability constants of novel Schiff bases 4-hydroxy-3-(1-((5-substitutedphenyl)-1,3,4-thiadiazol-2-yl)imino)ethyl)-2H-chromen-2-one with lanthanide metal ion Dysprosium (III) using a pH metric titration technique in 80%(v/v) ethanol-water mixture at three different temperatures 298K, 308Kand318K at an ionic strength of 0.1M NaClO4 were determined. The Calvin-Bjerrum method as modified by Irving-Rossotti has been employed to determine metal-ligand stability constant logK values. The thermodynamic parameters such as, Gibb’s free energy change, entropy change and enthalpy change associated with the complexation reactions were calculated.