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Updated: May 10, 2026

Determination of the Photoisomerization Quantum Yield of a Hydrazone Photoswitch
Published on: February 7, 2022
Bidirectional Photoswitching in the Linkage Isomerism of a Luminescent Iridium Sulfoxide Complex
Beibei Chen1, K M Anis Ul Haque1, Terry Frankcombe1
1School of Science, The University of New South Wales, Canberra, Australian Capital Territory 2610, Australia.
Abstract:
The photochemical behavior of [Ir(tpy)Cl3] (1), hitherto used mainly as a synthetic precursor in thermal reactions, is reported. Results showed that photosubstitution occurred under light, with solvent replacing one chlorido ligand to give [Ir(tpy)(S)Cl2]+, where S is the solvent (dmso, MeCN, H2O). Two isomeric photoproducts were discovered in dmso, identified as [Ir(tpy)(κS-dmso)Cl2]Cl (2A) and [Ir(tpy)(κO-dmso)Cl2]Cl (2B). 2A was the primary product under green light (505 nm), whereas 2B predominated at long-wave UV wavelengths. These isomers interconvert photochemically in dmso in a bidirectional linkage isomerism process that could be cycled at least five times over a period of >250 h without evidence of photodecomposition. Instances of photoswitches with photochemically driven forward and reverse processes such as this are relatively uncommon and lead to promising applications, e.g., in erasable information storage.
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