Stepwise Solvation of the Intramolecular-Charge-Transfer Molecule p-(Dimethylamino)benzonitrile

This paper presents a systematic study of gas-phase p-(N,N-dimethy1amino)benzonitrile (DMABN) both in a supersonic jet expansion and in a thermalized vapor. From the jet studies, the excited- and ground-state vibrational spectra of the isolated molecule are resolved, and the spectroscopy of the stoichiometric complex with water, methanol, ammonia, and acetonitrile in the beam is reported. It is concluded that 1:l complexes are not sufficient for the local perturbation to cause charge separation. At higher temperatures in the jet, we observe emission that we attribute to DMABN self-complexes. Under high pressure and temperature vapor conditions (>30 mTorr, 60 °C), red-shifted fluorescence from DMABN is observed. This is attributed to the charge-transfer state of DMABN in self-complexes.