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 IrIII complex with a covalently tethered azobenzene fragment was synthesized. Selective irradiation of the 1MLCT band of the IrIII complex induced an efficiently sensitized photoswitching of the dyad over a wide concentration range and even at high dilution. Beating diffusion by covalently linking a photosensitizing Ir complex to an azobenzene unit to achieve efficient indirect photoisomerization at low concentration.