Polymer complexes XXXIV. Potentiometric and thermodynamic studies of monomeric and polymeric complexes containing 2-acrylamidosulphadiazine

2-Acrylamidosulphadiazine (ASD) was synthesized and characterized by elemental analyses, IR and 1H NMR spectra. Proton–monomeric ligand dissociation and metal–monomeric ligand stability constants of ASD 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 initiator, the dissociation and stability constants of ASD were determined in polymeric form (PASD). The influence of temperature on the dissociation of ASD and the stability constants of their complexes in monomeric and polymeric forms were critically studied. The pK2H value of PASD was found to be higher than ASD, this means that the vinyl group in the monomeric form decreases the electron density 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 is quite reasonable because the ligand in a polymeric form is considered as a better complexing agent.