2-Hydroxychalcone-β-Cyclodextrin Conjugate with pH-Modulated Photoresponsive Binding Properties.

Stimuli-responsive supramolecular receptors are important building blocks for the construction of self-assembled functional materials. We report the design and synthesis of a pH- and light-responsive 2-hydroxychalcone-β-cyclodextrin conjugate () and its characterization by spectroscopic and computational methods. follows the typical reaction network of -chalcone-flavylium photoswitches. Upon light irradiation, can be photochemically converted into the -chalcone/hemiketal forms (/) under neutral pH conditions or to the flavylium cation () at acidic pH values. This stimuli-responsive β-cyclodextrin host, , was found to form stronger intramolecular self-inclusion complexes ( = 14) than ( = 3) and weaker than / (overall = 179), allowing control over their stability and binding properties by combinations of pH and light stimuli.