RADIATIVE AND RADIATIONLESS DEPOPULATION OF THE EXCITED INTRAMOLECULAR CHARGE-TRANSFER STATES - ARYL DERIVATIVES OF AROMATIC-AMINES

Photoinduced electron transfer in a series of aryl derivatives of aromatic amines has been studied in solutions. The intramolecular charge transfer (CT) leads to a large Stokes shift and large dipole moment in the fluorescent state. The charge recombination (CR) processes are observed by means of the luminescence quantum yields and kinetic measurements. The transition moment of the radiative depopulation of the CT state decreases with the increase of the steric hindrance to coplanarity between donor and acceptor entities and with increasing solvent polarity. The radiationless CR is controlled by two competitive mechanisms: internal conversion to the Franck-Condon ground state and intersystem crossing to the triplet manifold.