Electroactive poly(amino acids). Part 2. Copolymers of Nε-4-nitrobenzoyl-L-lysine with inactive amino acids: modified electrodes with these polymers and poly(pyrrole) and with poly{1-[2-(4-nitrobenzoyl)aminoethyl]pyrrole}

Abstract

Co-polymerization of the N-carboxyanhydrides derived from N^ε-4-nitrobenzoyl-L-lysine (NBL) and one of the amino acids, N^ε-4-benzoyl-L-lysine, L-leucine, and glycine afforded electroactive materials. These can be adsorbed onto platinum from dimethylacetamide solution. The electrochemical response of the adsorbed layers quickly deteriorates to give broad peaks on continuous cyclic voltammetry. Deterioration of the response is thought to be due to a combination of poor adhesion and conformational changes which accompany charging and discharging of the film. Poly{1-[2-(4-nitrobenzoyl)aminoethyl] pyrrole} forms a coherent film on platinum. It shows a good response due to the nitro group on continuous cyclic voltammetry. The height of this response falls with time due to loss of electroactive material. Poly(NBL) also forms a film by adsorption onto a 20–60 nm thick layer of poly(pyrrole) and the composite gives a response on continuous cyclic voltammetry that is much more stable than any of the previous cases. Coating platinum with poly(NBL) and then with poly(pyrrole) also gives a stable composite.