ELECTROCHEMICAL CHARACTERIZATION OF THE OXIDATION OF LB FILMS OF POLYPHTHALOCYANINATOSILOXANE

Highly ordered PcPS (phthalocyaninatopolysiloxane) thin films have bee n produced on a variety of substrates using Tangmuir-Blodgett thin-fil m deposition techniques, with coverages ranging from 1 to 100 molecula r layers. Siloxane-polymerized cofacial phthalocyanines, with alkoxyhy drocarbon side chains on the individual Pc units, yield molecules capa ble of forming highly ordered, densely packed LB films, with individua l polymeric-Pc chains ranging in size up to ca. 100 Pc monomer units e ach. These ultrathin films shows facile electron and ion transport dur ing electrochemical and chemical oxidation and notable stability of th e Pc cation radicals in the polymer chains in contact with both aqueou s and nonaqueous media. Coulometric and spectroelectrochemical data su ggest the oxidation of at least 80 --> 100% of the Pc rings at potenti als up to ca. 1.0 V and the onset of formation of Pc dication species. There is a strong anion dependence for both the extent and rate of ox idation of the PcPS films in aqueous media. Anion incorporation can oc cur over a wide potential range from aqueous media, however, without t he apparent low of film structure or stability.