STUDIES ON AROMATIC TRICHROMOPHORE SYSTEMS INCORPORATING ANTHRACENE MOIETIES .1. SYNTHESIS, FLUORESCENCE AND PHOTOREACTIVITY

Trichromophoric molecules (A2A, A2Pyr, A2Phen), incorporating two anthryl moieties, linked by a three-membered chain, and a third chromophore (anthracene, pyrene and phenanthrene) attached by a longer ester chain, have been synthesized. Their electronic absorption spectra and their fluorescence emission were studied in very dilute solution at room temperature in comparison with models representing the different absorbing parts of the trichromophore. Careful examination of their photophysical properties has shown the existence of triple complexes in the ground and excited states. The photochemistry of these molecules is governed by the '4pi + 4pi' cyclomerization of the bisanthracene part linked by the three-membered chain. The involvement of the excited complex on the pathway of the cyclomerization is not readily explainable.