Electrochemical and Physical properties of N-substituted arylmethylene pyrrole polymers and N-alkylmethine pyrrole copolymers

The electrochemical behaviour of N-arylmethylene and N-alkylmethine pyrrole monomers were investigated in their ability to be electropolymerised into polymer and co-polymer films with pyrrole using the techniques of cyclic voltammetry and scanning electron microscopy (SEM). N-substituted arylmethylene pyrrole monomers readily formed homopolymers by the oxidative electropolymerisation of pyrrole monomers by potentiostatic cycling in acetonitrile containing tetrabutylammonium perchlorate. The polymer films formed were brown in appearance and redox active, with the exception of the 1-((4-chlorophenyl)methyl)-1H-pyrrole (1d) which formed a pale yellow film lacking redox activity. The thickness of films produced calculated on the charge consumed followed the order 1e < 1b < 1h < 1i < 1f < 1a < 1g < 1c with the underlying morphology and thickness shown by SEM, for some monomers to mirror their structural characteristics. N-alkylmethine pyrrole monomers were found only to form copolymers with pyrrole after 20 scans of which only monomers 1m-1o were electrochemically active. Polymer 1 m, (D,L)-N-(1,2-dicarboxyethyl)-1H-pyrrole prepared from D,L-aspartic acid was shown capable of forming complexes with Cu+ and Cd2+ ions at a concentration of 1 × 10−4 M under an applied-ve field and to release the metal ion on stepping the potential to zero.