MULTICHROMOPHORIC CYCLODEXTRINS .5. ANTENNA-INDUCED UNIMOLECULAR PHOTOREACTIONS - PHOTOISOMERIZATION OF A NITRONE

A novel approach to photochemistry in constrained media based on anten na-induced photoreactions within a host cavity is described. Specific effects are to be expected from selective excitation of the reactants included in the cavity by means of energy transfer from appended chrom ophores. A kinetic scheme accounting for energy transfer-relayed unimo lecular photoreactions is presented. A system was designed to illustra te this new strategy; it consists of a heptachromophoric cyclodextrin (CD-NA) promoting the photoisomerization of a nitrone. Analysis of the experimental data shows that the kinetic scheme is valid and demonstr ates that energy transfer from the antenna can be used to tune both re action pathways and kinetics.