Photoresponsive supramolecular polymers based on quadruple hydrogen-bonding and a photochromic azobenzene motif

A photoresponsive quadruple hydrogen-bonded supramolecular polymer was constructed using photochromic azobenzene and ureidopyrimidinone motifs. The E-isomer of azobenzene preferred to form linear supramolecular polymers and further aggregate as its concentration increased. After irradiation with UV light, the E-isomer was converted into the Z-isomer, and the Z-isomer could also self-assemble into supramolecular polymers with a relatively low degree of polymerization. Moreover, supramolecular polymer films were fabricated by a solution casting process. These supramolecular polymers showed highly reversible trans/cis photoisomerization in both solutions and films under alternating UV and visible light irradiation.