Photoswitchable Arene Ruthenium Complexes Containing o-Sulfonamide Azobenzene Ligands

A series of arene ruthenium complexes containing o-sulfonamide azobenzene ligands were synthesized and found to exhibit uncommon coordination pattern with an 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, the sulfonamide moiety, and azobenzene substitution, as revealed by structure-property studies.