THE MOLECULAR AND ELECTRONIC-STRUCTURE OF DIBENZO[Q,P]CHRYSENE - A TWISTED CASE

Studies of the electronic structure and spectrum of dibenzo [g,p]chrys ene, carried out in 1965 and 1985, were not fully conclusive. They are repeated here by means of improved linear dichroism spectroscopy, qua ntum mechanical calculations of the spectra, and structural studies. B ased on the new evidence, especially the observed transition moment di rections, it is concluded that the molecule is nonplanar with D2 symme try. The experimentally determined transition moment directions also a llow a complete assignment of all significant transitions in the regio n 25 000 to 45 000 cm-1. All three possible (perpendicular) transition moment directions are represented among the observed electronic trans itions.