A supramolecular enzyme model catalyzing the central cleavage of carotenoids.

Several bis-beta-cyclodextrin porphyrins have been prepared as supramolecular receptors of carotenoids. The binding constants of carotenoids to receptors were determined by quenching the fluorescence of the porphyrins on hydrophobic binding of carotenoids within the cavities of cyclodextrins. K(a)=8.3 x 10(6) M(-1) was calculated for binding of beta,beta-carotene to bis-beta-cyclodextrin Zn porphyrin. The corresponding Ru complex catalyzes the central cleavage of carotenoids in the presence of tert-butyl hydroperoxide in a biphasic system.