Photoresponsive Phosphate Coordination Using Azobenzene-Spaced Bis-tris(urea) Ligand

Abstract

Given the nondestructive nature and high spatiotemporal resolution of the light source, studies of photoresponsive systems have gained great attention and made considerable progresses in the past decades. By incoporationg photoswitch molecules with noncovalent interaction, photoresoive, supramolecular systems can be designed for tailored properties, e.g., guest delivery, catalysis, sensing, and information processing. Here, we introduced a new photoresponsive ligand (L) comprised of azobenzene spacer and two tris(urea) binding moiety. The latter component displayed characteristic coordination property with anions. Upon light irradiation, we observed reversible photoswitching of free ligand. The Z/E thermal relaxation half-life of free ligand L was determined to be 3.4 h at room temperature. By coordinating to phosphate anion, double helicate structure was believed to form and can be subsequently regulated by light and heat.