Electronic interaction and charge transfer efficiencies in triaromatic donor-acceptor systems. An experimental and theoretical study

To address the issue of electronic interaction between donor (D) and acceptor (A) moieties in intramolecular charge transfer reactions a series of chemically closely related extended pi-systems has been investigated, These compounds contain pyrene and organic methyl ester derivatives connected via a phenyl group. Our steady-state fluorescence studies reveal that only particular compounds exhibit strong charge transfer (CT) emission in solution. To elucidate the experimental results we have performed semiempirical CNDO/S-CI calculations which indicate that the electronic coupling and Coulomb stabilization of the CT state are strongly dependent on the nodal properties of the D/A orbitals. (C) 1998 Elsevier Science B.V.