Potentiometric and Thermodynamic Studies of 2-Acrylamidosulfamethazine and Its Metal Complexes in Monomeric and Polymeric Forms

2-Acrylamidosulfamethazine (ASM) was synthesized and characterized by elemental analyses and IR spectroscopy. Proton-monomeric ligand dissociation and metal-monomeric ligand stability constants of ASM with some metal ions were determined potentiometrically in 0.1 M KCl and 40% (v/v) ethanol–water mixture. In the presence of 2,2′-azobisisobutyronitrile as an initiator, the dissociation and stability constants of ASM were determined in polymeric form (PASM). The influence of temperature on the dissociation of ASM and the stability constants of their complexes in monomeric and polymeric forms were precisely studied. The pKH value of PASM was found to be higher than ASM, which indicates that the vinyl group in the monomeric form decreases the electron density on nitrogen and hence reduces the N–H bond strength. The stability constants of the metal complexes in polymeric form are higher than those of the monomeric form. This reveals that the ligand in a polymeric form may be considered as a better complexing agent.