KINETIC AND THERMODYNAMIC STUDIES ON NEW INTRAMOLECULAR MIXED EXCIMERS IN ANTHRACENE PHENANTHRENE AND ANTHRACENE PYRENE LINKED SYSTEMS

An analysis of the intramolecular mixed excimer formation in (9-anthrylmethyl) (9-phenanthrylmethyl)ether (I) in methylcyclohexane (MCH) and methanol (MeOH) was carried out, based on spectral data and time-dependent fluorescence intensities at different temperatures and wavelengths. The rate constants for formation and deactivation of the mixed excimer and the values of DELTA H and DELTA S were determined under stationary and dynamic conditions for I. The study on (9-anthrylmethyl) (1-pyrenylmethyl) ether (II) was limited to Stevens-Ban analysis due to the closeness of the first-singlet excited states of the anthracene and pyrene chromophores. These new intramolecular mixed excimers display no significant solvent polarity effect and their thermodynamic data are similar to those of homoexcimers. Consequently their stabilization seems to originate more from exciton resonance than from charge transfer states.