CONFORMATION-DEPENDENT INTRAMOLECULAR EXCIPLEX FORMATION IN JET-COOLED BICHROMOPHORES

Bichromophore compounds consisting of anthracene and naphthalene subun its linked by the alkyl (CH2)(3) and the ethereal CH2-O-CH2 chain have been studied under supersonic jet conditions in the region of the fir st electronic transition of anthracene by laser-induced fluorescence. Intramolecular exciplex formation has been observed in the 1-substitut ed naphthalene derivative involving the CH2-O-CH2 spacer, whereas the trimethylene bridge compound as well as the 2-substituted naphthalene ethereal derivative exhibit only the resonance fluorescence characteri stic of a locally excited anthracene molecule. These different behavio urs reproduce the photophysical properties of these bichromophores in solution and have been discussed in terms of ground-state geometries. (C) 1998 Elsevier Science B.V. All rights reserved.