Electrochemical study of multilayer films built on glassy carbon electrode with polyoxometalate anions and two multi-charged molecular cationic species

Abstract

Electrochemical results are reported on complex films built onto glassy carbon electrodes. Each film involves one polyoxometalate ${\left( {{\text{PMo}}_{{{\text{12}}}} {\text{O}}^{{{\text{3 - }}}}_{{{\text{40}}}} {\text{,}}\;{\text{PW}}_{{{\text{12}}}} {\text{O}}^{{{\text{3 - }}}}_{{{\text{40}}}} {\text{,}}\;{\text{SiMo}}_{{{\text{12}}}} {\text{O}}^{{{\text{4 - }}}}_{{{\text{40}}}} \;{\text{or}}\;{\text{SiW}}_{{{\text{12}}}} {\text{O}}^{{{\text{4 - }}}}_{{{\text{40}}}} } \right)}$ and one or two cations : methyl viologen and meso-tetra(4N-methylpyridyl porphyrin). In a given film, layers of polyoxometalate anions alternate with layers made of one of the two cations. Electrochemical studies indicate the effective building of films with polyoxometalate and both cations present. They also demonstrate that, in the film building process, the electrochemical response of every new layer is influenced by coulombic interactions and conducting properties with the immediately underlying layer.