Photo-responsive Supramolecular Polymer Based On P-Sulfonatocalix [4] Arene And β-cyclodextrin Derivatives

Molecular self-assembly is one of the hot topics in supramolecular chemistry. Cyclodextrin and calixarene, considered as two most important hosts, have been well explored in molecular recognization and self-assembly. A new water-soluble supramolecular polymer based on p-sulfonatocalix[4]arene derivative with an azobenzene unit substituted on the lower rim andβ-cyclodextrin derivative attached by viologen has been constructed. In aqueous solution, p-sulfonatocalix[4]arene derivative includes viologen unit through ionic interactions while the cavity ofβ-cyclodextrin derivative includes azobenzene unit through hydrophobic effect. Due to this co-interactions, a linear self-assembling polymer can be constructed by adding the p-sulfonatocalix[4]arene derivative andβ-cyclodextrin derivative together with mole ratio of 1:1 in aqueous solution. The trans-configurated azobenzene unit can be photoisomerized to cis-configuration by UV-irradiation. The association constant between cis-azobenzene andβ-CD derivative in aqueous solution is much smaller, so cis-azobenzene unit partly dethreads from the cavity of P-cyclodextrin derivative, thus dissembles the polymer. It is a self-assembly polymer controlled by light. Each monomer is a pseudorotaxane withβ-cyclodextrin acting as a stopper.