Electrochemical preparation and characterization of zinc porphyrin-coated electrodes

Attachment of metalloporphyrins to electrodes by means of electrochemical polymerization of suitable complexes has been developed intensively over the past few years [l-lo]. These supported metalloporphyrins were aimed at electrocatalysing redox or organic reactions [3,11,12] and much attention has been drawn to their photoelectrochemical properties which are the result of the structural analogy of these complexes to natural plant chlorophyll [13,14]. The use of these new organic materials as semiconductors for light energy conversion was largely exemplified by electroactive zinc porphyrin films [9,10,15,16]. In order to promote zinc porphyrin-type molecules as thin films in photoelectrochemical studies, we report here the electrochemical polymerization of a new pyrrole-substituted zinc(II)-porphyrin (5(4-(l-pyrrolyljphenylj-10,15,20-triphenylporphine zinc(B) [ZnP] (Fig. l), since pyrrole-substituted complexes appear to be among the best candidates for the preparation of polypyrrole-based modified electrodes. The aim of this work was the characterization of the electrochemical and the spectrophotometric behaviour of the zinc porphyrin fixed into the polypyr-