Stable redox and electronically conducting thin films containing Fe(bpy)₃²⁺ bound to 3-substituted poly(thiophenes)

Anodic electropolymerization of two ß-substituted thiophenes bearing iron tris(bipyridyl) redox centres yields a conducting thin film that is stable to anodic cycling and prolonged storage.

The modification of electrode surfaces with electroactive polymeric thin films, particulary films that incorporate redox centres, has attracted much attention recently. Most of the examples described have involved binding of the molecular electroactive species to the nitrogen of pyrrole prior to electropolymerization [1, 2]. The resultant polymeric films are redox conductors [3] but possess only modest electronic conductivity. It is now appreciated that ß-substituted thiophenes may be electropolymerized to give highly-conducting films and that many different substituents are tolerated without significantly impairing the film conductivity [4]. We therefore determined to prepare electronically-conducting films that were functionalized with a stable, reversible redox centre. In particular, systems were sought in which the redox centre was conjugated to the electronically-conducting polymer backbone.