Efficient Sensitized Z→E Photoisomerization of an Iridium(III)-Azobenzene Complex over a Wide Concentration Range

To improve the sensitized Z→E photoisomerization of azobenzenes, and circumvent the threshold concentration necessary for the bimolecular photoinduced electron transfer reaction to generate the rapidly isomerizing Z-azobenzene radical anion, an Ir^III complex with a covalently tethered azobenzene fragment was synthesized. Selective irradiation of the ¹ MLCT band of the Ir^III complex induced an efficiently sensitized photoswitching of the dyad over a wide concentration range and even at high dilution.