Resonance Raman measurement of anthracene derivative cation and anion radicals using a column-electrolytic continuous-flow method

Abstract

Abstract The resonance Raman (RR) spectra of both cation and anion radicals of 9,10-diphenyl- and 9,10-dimethylanthracene could be successfully observed using a column-electrolytic continuous-flow method. In the present case, it was found that the cation and anion radicals of the identical molecules have similar profiles in the RR spectra. However, systematic lower wavenumber shifts were observed in the anion radicals compared with the cation radicals for the RR bands between 1000 cm−1 and 1600 cm−1 which are mainly attributed to the C-C stretching modes. Because the lower wavenumber shift of the C-C stretching mode indicates an increase in the single-bond character, it could be concluded that the anion radicals had loosened the anthracene ring structure rather than the cation radicals. Moreover, the degree of single-bond character seemed to spread over the whole anthracene ring. This result shows that the changes in the structure between the cation and anion radicals in solution can be comprehended directly through vibrational measurements in RR spectroscopy.