STUDY OF BIMOLECULAR PROCESSES IN TERNARY CYCLODEXTRIN COMPLEXES IN THE SOLID-STATE BY DIFFUSE-REFLECTANCE LASER FLASH-PHOTOLYSIS

The photochemistry of binary inclusion complexes of 4-nitroveratrole ( NV) and p-dinitrobenzene (DNB) with beta-cyclodextrin (beta-CD) and of ternary inclusion complexes of NV or DNB and 1-phenylethylamine (PhEA ) with beta-CD has been examined in the solid state by diffuse reflect ance laser flash photolysis. The binary NV/beta-CD complex shows a tra nsient absorption signal assigned to the triplet excited state of NV. The binary DNB/beta-CD complex shows a transient signal assigned to th e protonated radical anion of DNB formed via hydrogen abstraction from the beta-CD cavity. Laser excitation of the ternary complexes generat es the corresponding radical ion pairs via photoinduced electron trans fer from the amine to the nitroaromatic tripler state. Comparison with previously described conventional laser flash photolysis studies in s olution shows that the investigation of solid ternary CD inclusion com plexes by diffuse reflectance laser flash photolysis is valuable in th e case of bimolecular photoreactions that are difficult to study in so lution due to the existence of other competitive processes. (C) 1997 E lsevier Science S.A.