Inversion of states in two conformers of 1,8-bis(dimethylamino) naphthalene - the proton sponge

The S-1 <-> S-0 transitions of two conformers of 1,8-bis(dimethylamino) nap hthalene, the "proton sponge", have been studied by semiempirical AM1 calcu lations. They reveal that "inversion of states" occurs in the asymmetric co nformer DMAN-2, which in the gas phase may be emitted from the L-1(a) state in comparison to the L-1(b) State in symmetric DMAN-1. It was also conclud ed that because of the mixed character of the HOMO-1 orbital in both confor mers, a certain CT contribution to the S-0 <-> S-1 transition has to be tak en into account. The calculated maxima of absorption and emission have been compared to those experimentally obtained in supersonic expansion. (C) 200 0 Elsevier Science B.V. All rights reserved.