Interactions of polymer–small molecule complex with cupric (II) ions in aqueous ethanol solution

A complex was prepared by mixing ethanol solutions of poly(4-vinyl pyridine) (P4VP) and 4-amino benzoic acid. The complex (PEC) formation was studied by 13C NMR, IR spectroscopy, differential scanning calorimetry and potentiometry. It was found that hydrogen bond is formed between P4VP and 4-amino benzoic acid. Dissolution was assessed visually at room temperature using dimethyl formamide, dimethyl sulfoxide, methanol, ethanol, ethanol–water. After dissolution of PEC in aqueous-ethanol (50% v/v) solution, the interaction of PEC with Cu2+ ions has been investigated by potentiometric titration. The average number of ligands coordinated with the central metal ion and the stability constants of PEC–metal complex were determined.