PREPARATION AND CHARACTERIZATION OF ELECTRODES MODIFIED WITH IRON PORPHYRINS IMMOBILIZED IN A POLY(AMINO ACID) MATRIX

Controlled reaction of 1-(3-aminopropyl)imidazole with poly(gamma-ethy l L-glutamate) leads to conversion of some side-chain ester groups to amides. The functionalised polymer is characterised by H-1 NMR spectro scopy. Imidazole complexes have been formed between this functionalise d polymer and 5,10,15,20-tetraphenylporphyrin iron(III) chloride and a lso deuteroporphyrin-IX dimethyl ester iron(III) chloride. Films of th e polymer-porphyrin complexes formed on platinum and on tin oxide coat ed! glass show reversible redox activity in acetonitrile and in aqueou s electrolytes, Both redox states of iron are characterised as bis-imi dazole ligated by their UV-VIS spectra. The influence of the degree of polymerisation of the starting poly(gamma-ethyl L-glutamate), the com position of the aqueous electrolyte and the oxidation state of the iro n centre on the stability of the hydrogel films towards redox cycling is examined.