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 1 MLCT band of the IrIII complex induced an efficiently sensitized photoswitching of the dyad over a wide concentration range and even at high dilution.