Complexation with Cyclometalated Iridium(III): Restriction to trans-cis isomerism of 4,4'-Styryl functionalized 2,2'-Bipyridyls

Sinha, Soumalya (2014) Complexation with Cyclometalated Iridium(III): Restriction to trans-cis isomerism of 4,4'-Styryl functionalized 2,2'-Bipyridyls. Masters thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

An account of the photoinduced behaviour of 4,4-styryl functionalized 2,2′-bipyridyls (L1 – L2) and their cyclometalated heteroleptic iridium(III) complexes (1a - 2a) with L1 - L2 as ancillary ligands has been presented here. The ligands show expected trans-cis isomerism on exposure to light at 366 nm. Interestingly, the NMR and electronic spectral data, along with the X-ray structure elucidation of the iridium complexes support only restricted rotation of single bonds around C=C. The complexes 1a - 2a, on exposure to visible light finally transforms to complexes 1c - 2c through the intermediate states 1b - 2b. The complexes 1c - 2c are thermally switchable to 1a - 2a at 70C. The trans-cis isomerisation of styryl functionalized bipyridyl is ceased and restricted rotation of single bonds is observed due to metal chelation.

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