Photochemical and structural properties of the cyclodextrin inclusion complexes of aryl-olefin bichromophores

The photoproducts distribution of 2-allylphenol (1), 2-allylanisole (2) and 2-allylaniline (3) were strongly modified by inclusion of these compounds in cyclodextrin (CD) cavities. Under these conditions photocyclization for 1 and 3 and di-π-methane photorearrangement for 2, occurring in homogeneous solvents, were strongly depressed and photohydration of the acyclic olefin moiety was found to be by far the predominating photoprocess. The determination of the stability constants, the absorption properties, the steady state and time resolved fluorescence, the induced circular dichroism, accompanied by conformational calculations, of the CD complexes of 1-3, allowed a rationale to be reached for the modified photochemical behavior of these compounds within the CD cavity, based on the structure of the 1:1 host-guest ground state complexes and on the influence of the intracavity interactions on the reactive singlet excited state of 1-3.