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 π-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.