Photophysics of intramolecular electron donor—acceptor systems; N-carbazolyl(CH2)ntetrachlorophthalimide

In systems N-carbazolyl—(CH₂)_n—tetrachlorophthalimide (n = 2, 3, 4, 7) virtually complete quenching of the carbazole fluorescence via an intramolecular electron-transfer mechanism occurs, with concomitant formation of an emissive polar excited state. The rate of formation of this polar excited state is found to exceed considerably those reported for formation of intramolecular exciplex states in other non-conjugated bichromophoric systems with a less pronounced electron donor—acceptor character.