POSSIBLE MECHANISM OF THE MULTIPLE FLUORESCENCE OF P-N,N-DIMETHYLAMINOBENZONITRILE AND RELATED COMPOUNDS

Ab initio and CNDO/s calculations support a mechanism which involves a geometrical relaxation (i.e., the twist of the bond between the ring and NR2 group) for the appearance of the long wavelength fluorescence (Fa) observed in some p-substituted dimethylanilines. For the twisted geometries of the dimethylamino compounds a high charge transfer occurs in a low lying excited 1A state for which this geometrical relaxation seems to be energetically favourable. The polarized nature of such a 1A state might be responsible for the strong solvent dependence of the Fa fluorescence. © 1979.