Luminescent cyclometalated dialkynylgold(III) complexes of 2-phenylpyridine-type derivatives with readily tunable emission properties

Ka Man Vonika AU, Keith Man-Chung WONG, Nianyong ZHU, Vivian Wing-Wah YAM

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Abstract

A novel class of luminescent dialkynylgold(III) complexes containing various phenylpyridine and phenylisoquinoline-type bidentate ligands has been successfully synthesized and characterized. The structures of some of them have also been determined by X-ray crystallography. Electrochemical studies demonstrate the presence of a ligand-centered reduction originating from the cyclometalating C^N ligand, whereas the first oxidation wave is associated with an alkynyl ligand-centered oxidation. The electronic absorption and photoluminescence properties of the complexes have also been investigated. In dichloromethane solution at room temperature, the low-energy absorption bands are assigned as the metal-perturbed π-π* intraligand (IL) transition of the cyclometalating C^N ligand, with mixing of charge-transfer character from the aryl ring to the pyridine or isoquinoline moieties of the cyclometalating C^N ligand. The low-energy emission bands of the complexes in fluid solution at room temperature are ascribed to originate from the metal-perturbed π-π* IL transition of the cyclometalatng C^N ligand. For complex 4 that contains an electron-rich amino substituent on the alkynyl ligand, a structureless emission band, instead of one with vibronic structures as in the other complexes, was observed, which was assigned as being derived from an excited state of a [π(C≡CC6H 4NH2)→π* (C^N)] ligand-to-ligand charge-transfer (LLCT) transition. Copyright © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Original languageEnglish
Pages (from-to)130-142
JournalChemistry - A European Journal
Volume17
Issue number1
DOIs
Publication statusPublished - 03 Jan 2011

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Citation

Au, V. K.‐M., Wong, K. M.‐C., Zhu, N., & Yam, V. W.‐W. (2011). Luminescent cyclometalated dialkynylgold(III) complexes of 2-phenylpyridine-type derivatives with readily tunable emission properties. Chemistry - A European Journal, 17(1), 130-142. doi: 10.1002/chem.201001965

Keywords

  • Acetylides
  • Cyclometalation
  • Excited states
  • Gold
  • Luminescence