Near Infrared Polyene Radical‐Cation Derived from 7,8‐Dihydrobenzo[c,d]Furo[2,3‐f]Indole: Synthesis, Spectra and Nature of Electron Transitions

Abstract

AbstractThe stable polyene cation‐radical containing the 7,8‐dihydrobenzo[cd]furo[2,3–f]indol terminal groups was synthesized and the features of its lowest electron transitions were studied, in detail. The electronic structure and absorption spectra of the polyene cation‐radical obtained, was compared with the electronic and spectral properties of the corresponding neutral poleynes, dications and related polymethine dye having the same terminal groups. While polyene and its dication absorb in the relative short wavelength spectral region, the polymethine‐cation absorbs in the long wavelength region; it is shown that two splitting bands appear in the spectra of the polyenic cation‐radical: the low‐ intensive long wavelength band (≈ 1200 nm) and of the high‐ intensive short wavelength band (≈800 nm); they take correctly into consideration splitting of excited states, generated by α‐ and β‐electrons.