Effect of Azobenzene Regioisomerism on Intrinsically Curved Supramolecular Polymers

Supramolecular polymerization of two regioisomeric naphthalene-azobenzene dyads bearing barbituric acid and tri(dodecyloxy)phenyl units were studied in nonpolar solvent. Supramolecular polymers of the two compounds differ considerably in their topologies. While the isomer of which azobenzene unit was introduced along to its longer molecular axis formed randomly coiled supramolecular polymers with intrinsic curvature, the other of which azobenzene unit was introduced along to its shorter molecular axis formed linearly extended supramolecular polymers. Furthermore, due to their different degrees of geometrical changes accompanied with photoisomerization of the azobenzene unit, only the former showed a large topological change upon photo-irradiation. The different structural and photoresponsive properties can be attributed to the distinct geometries of supermacrocyclic hydrogen-bonded intermediates (rosettes).

Automated summary

The supramolecular polymerization of two regioisomeric naphthalene-azobenzene dyads bearing barbituric acid and tri(dodecyloxy)phenyl units in nonpolar solvent was studied, revealing considerable differences in their topologies. One isomer formed randomly coiled supramolecular polymers with intrinsic curvature, while the other formed linearly extended supramolecular polymers. Only the former showed a large topological change upon photo-irradiation due to different geometrical changes accompanied with photoisomerization of the azobenzene unit. These differences were attributed to the distinct geometries of supermacrocyclic hydrogen-bonded intermediates (rosettes).