Infrared spectroelectrochemical evidence for alkyl viologen radical monomers in acetonitrile

Abstract

Fourier-transform infrared reflection–absorption spectra of the electrogenerated radical monocation of N,N′-diheptyl-4,4′-dipyridinium dibromide (HV) in monomeric (acetonitrile solutions) and dimeric-film (aqueous media) forms were obtained using potential-difference and polarisation-modulation techniques. By comparison with results for the radical products obtained by the electroreduction of N,N′-dimethyl-4,4′-dipyridinium (MV) and 2,2′-dicyano-N,N′-dimethyl-4,4′-dipyridinium (DCMV) in both media, evidence was obtained for an intramolecular intensity enhancement of selected modes for the solution monomer.