SUPRAMOLECULAR PHOTOCHEMISTRY OF SYMMETRICAL AND ASYMMETRIC DIAZONAPHTHOQUINONE DERIVATIVES

Bi-and trichromophoric 1,2-Diazonaphthoquinone systems (DNQ systems) a re characterized by a non-reciprocity behaviour which means that the r ate of photolytic cleavage depends on the concentrations of starting c ompounds and intermediates of the photodecomposition, and the quantum yield changes with progressing reaction. The photolysis (lambda = 436 nm) of the asymmetrically substituted model compound, which contains t wo chromophores of various reactivity (DNQ4 and DNQ5) at one benzophen one back-bone molecule, effects a sequential photolytic mechanism. The excitation energy is transferred from the local excited DNQ5 (donor) to the DNQ4 (acceptor). Different molecular environments were found fo r each DNQ-chromophore in di- and tri-(DNQ-5-sulfonyl-oxy)-benzophenon e, detected by H-1-, C-13-, N-15-NMR, quantum chemical calculations an d single-crystal X-ray analysis. The effect of the change in the elect ronic structure on the photoreactivity is distinct in particular of 2- DNQ chromophore. An energy transfer between all DNQ chromophores exist s.