Solvent parameter based on the exciplex emission of (2-naphthoxy)polyoxalkyl p-cyanobenzoates

The fluorescence spectra of (2-naphthoxy)polyoxalkyl p-cyanobenzoates (1-3) were analyzed in terms of emission maxima, lifetimes, and quantum yields o f the emissions from the locally excited state and the exciplexes (EX) stat e in 15 kinds of solvents from cyclohexane to acetonitrile. The emission in benzene, toluene, and 1,4-dioxane were deviated from usual Mataga-Lippert plots of EX-emission maxima of 1-3 versus solvent parameter, Delta f. In or der to modify Delta f parameter, we develop new empirical solvent parameter (E-M(2)) based on the intramolecular Ut emission of 5-(2-naphthoxy)-3-oxa- 1-pentyl p-cyanobenzoate (2). (C) 1994 Elsevier Science S.A. All rights res erved.