Photochromic Barbiturate Pendant-Containing Benzo[ b]phosphole Oxides with Co-Assembly Property and Photoinduced Morphological Changes

A series of novel barbiturate pendant-containing benzo[b]phosphole oxides has been demonstrated to exhibit photochromic and co-assembly properties. Both the open form and the photogenerated closed form of the diarylethene-based benzo[b]phosphole oxides have displayed color changes with new appearance of the bathochromic-shifted lowest-energy absorption bands upon addition of the H-bonding ditopic receptor that is complementary to the barbiturate groups, probably resulting in the formation of a supramolecular polymer. The co-assembly mixtures have displayed dissociation and association processes upon heating and cooling, respectively. Moreover, both the unassembled and co-assembled states of the benzo[b]phosphole oxide have exhibited photoinduced coloration, leading to a near-infrared absorption behavior. Multiaddressable states of the co-assembly mixture with multiple colors have been achieved via the combination of photochromism and thermochromism. More interestingly, photoinduced morphological changes from extensive porous network structures to ring-like aggregates have been observed for the co-assembly upon photoirradiation. The present work provides important insight for further developments of the multiaddressable systems and the supramolecular polymers with photo- and thermo-responsive behaviors, paving the way for the future design of photochromic materials with interesting photocontrollable functions.