Selective response mechanism of a platinum disk electrode modified with polyacrylamide membrane conjugated with gallium(III) phthalocyaninate Original Research Article

A non-plasticized polyacrylamide polymer (PAA) coupled with (phthalocyaninato) gallium(III) ([Ga(pc)]+), PAA–[Ga(pc)], was first synthesized, and the potentiometric response behavior of this PAA–[Ga(pc)] modified platinum electrode to certain ions was examined in the non-aqueous solvents acetonitrile (AN), dimethylacetamide (DMA), and N-methylpyrrolidinone (NMP). The electrode showed a Nernstian or near-Nernstian response to CN− and F− in AN, DMA, and NMP, but it showed a non-thermodynamic response to Cl−and Br− in all the above solvents. Both spectrophotometric and cyclic voltammetric methods were used to investigation the reaction of [Ga(pc)]+ with the ions in the solvents. The results revealed that the special selective response phenomena were due to the complex formation reactions of the ions with [Ga(pc)]+. The reaction mechanisms were determined on the basis of the shift of the maximum absorption peaks, the appearance of the new peaks on UV–vis spectra for [Ga(pc)]+ in the presence of CN− and F− and the clear difference in the redox voltammogram for [Ga(pc)]+ at the platinum electrode between the addition of F− and Br− in DMA. There were no obvious differences between the three solvents in terms of their influence on the complexing. It was concluded that the electrode might have applications in obtaining the solubility product of NaF in AN.