Copper(II) complex properties of a basic polymer containing SO2 group in the main chain

Cu(II) complexes of an aminic polymer containing sulphone have been studied at 25°C in aqueous solution at different pH's by potentiometric, calorimetric, visible and e.p.r, spectroscopic techniques. The potentiometric and spectroscopic data reveal the presence of two different complexes: the first CuL 2(L refers to the repeating unit of the polymer) presents a 'sharp' stability constant. This indicates that log/~ is unaffected by pH at different polymer/Cu(II) molar ratios. This species reaches a maximum concentration of 30~o with respect to the ligand. From e.p.r, measurements, spectrophotometric and calorimetric data we can hypothesize the coordination of one nitrogen and one oxygen probably belonging to the sulphone. The second is a dihydroxo complex Cu(OH)2L whose stability constant is 'apparent' and decreases with increasing pH, while AH ° is 'sharp'. E.p.r. and visible spectroscopic parameters are reported and the thermodynamic data are discussed