Structural studies of supramolecular beta-cyclodextrin complexes with butyrophenone and valerophenone: an explanation for photochemical reaction modification

X-Ray crystallographic studies of beta-cyclodextrin (beta-CD) inclusion com plexes with butyrophenone and valerophenone characterize these complexes as 2:2 beta-CD/guest systems with the alkyl chains of the included guest mole cules conformationally restricted; the structures explain the reported obse rvation of the modification of the Norrish type II photoreaction for the in cluded aryl alkyl ketones in crystalline beta-CD complexes.