Potentiometric response mechanism of a poly(acrylamide)-phthalocyaninato tin(II) film coated platinum electrode in acetonitrile and N,N-dimethylacetamide.

A new sensor constructed by a platinum electrode coated with a non-plasticized poly(acrylamide) polymer (PAA) film coupled with phthalocyaninato tin(II) ([Sn(II)(pc)]) was developed. The potentiometric response behavior of this PAA-[Sn(II)(pc)] electrode for such anions as CN-, F-, Cl-, and Br- in dimethylacetamide and acetonitrile were investigated. The electrode showed a Nernstian response to CN- and F- and a quite poor response to Cl- and Br-. The mechanism of the peculiar selective response was studied by cyclic voltammetric and spectrophotometric methods. The voltammetric investigation suggested that the charge of the host compound in the sensor membrane had no effect on the potential response of the electrode. It was also found by a spectrophotometric investigation that the complexing of [Sn(II)(pc)] with CN- and F- lead to the selective response of the electrode. The motive force of the complexing was considered to be a ligand exchange of CN- or F- with molecules at the axial site of [Sn(II)(pc)] due to solvent effects to the interest anions.