Photoswitchable Arene Ruthenium Complexes Containing o-Sulfonamide Azobenzene Ligands

A series of arene ruthenium complexes containing ortho-sulfonamide azobenzene ligands were synthesized and found to exhibit uncommon coordination pattern with exocyclic N=N bond. Upon irradiation, these complexes cleanly undergo (E)→(Z) photoisomerization followed by thermal (Z)→(E) isomerization (upon resting in the dark) whose rate is dependent on the solvent, the nature of the arene group, sulfonamide moiety and azobenzene substitution, as revealed by structure-property studies.