Electronic spectra of azanaphthalenes. Mixed crystal spectra of 1,6-naphthyridine- d6, cinnoline- d6, and quinoline- d7

The electronic spectra of 1,6-naphthyridine- d₆, cinnoline- d₆, and quinoline- d₇ have been recorded. For each molecule only one n,π ^∗ singlet state is identified and the spectral analyses proposed are in close correspondence to those reported for the fully protonated species. Features of particular interest are the reduced prominence of sites and the many instances of crystal induced coupling of vibronic bands.