DETERMINATION OF STABILITY CONSTANT OF CU (II)-NICOTINATE COMPLEX BY pH-METRIC STUDIES
Nicotinic acid (pyridine-3-carboxylic acid), Niacin forms complexes with many metals. It may behave as mono, bi and tri dentate ligand but mostly co-ordinates as monodentate ligand.
Complex formation of Niacin with different metals is a pH dependent reaction. In this study potentiometric results were used for the calculation of stability constant. These results show that complexes of Nicotinic acid and Cu, forms (like ML, ML2) at different pH. The stability constant was also calculated at different temperature (35 ?C, 40 ?C, 45 ?C, 50 ?C). pH-metric titration was also done by different mole ratios and results shows that best ratio is 1:2. Thermodynamic values ?H, ?S and ?G were determined by stability constant (at different temperature), these values suggests that ML2 of Cu (II)-Nicotinate complexes are more stable than ML1 Cu (II)-Nicotinate complex.