The interaction between the network of chemical reactions of the compound 4',7-dihydroxyflavylium and beta-cyclodextrin was studied by means of pH jumps, followed by UV-vis absorption, flash photolysis, stopped flow, and NMR. The trans-chalcone is the network species exhibiting the strongest interaction with the host. In moderately acidic medium, 95% of the trans-chalcone, 2.5 X 10(-5) M, in the presence of beta-cyclodextrin, 9 x 10(-3) M, is expected to fill the host cavity (association constant 2.2 x 10(3) M-1). In contrast, flavylium cation does not interact (association constant approximate to 0). Irradiation of the trans-chalcone in the presence of beta-cyclodextrin 9 mM leads to the flavylium cation appearance. Light is thus capable of removing the trans-chalcone from the beta-cyclodextrin, leaving the cavity empty. The system is reversible and trans-chalcone goes back to the initial state upon switching off the light due to the thermodynamic favorable conversion of flavylium cation to trans-chalcone in the presence of beta-cyclodextrin.