936013-77-3Relevant academic research and scientific papers
A class of luminescent cyclometalated alkynylgold(III) complexes: Synthesis, characterization, and electrochemical, photophysical, and computational studies of [Au(C∧N∧C)(C≡C-R)] (C∧N∧C = κ3C,N,C bis-cyclometalated 2,6-diphenylpyridyl)
Wong, Keith Man-Chung,Hung, Ling-Ling,Wai, Han Lam,Zhu, Nianyong,Yam, Vivian Wing-Wah
, p. 4350 - 4365 (2007)
A new class of luminescent cyclometalated alkynylgold(III) complexes, [Au(RC∧N(R′)∧CR)(C≡ CR″)], i.e., [Au(C∧N∧C) (C≡CR″)] (HC∧N∧CH = 2,6-diphenylpyridine) R″ = C 6H5 1, C6H4-Cl-p 2, C 6H4-NO2-p 3, C6H4- OCH3-p 4, C6H4-NH2-p 5, C 6H4-C6H13-p 6, C6H 13 7, [Au(tBuC∧N∧CtBu)(C≡CC 6H5)] 8 (HtBuC∧N∧CtBuH = 2,6-bis(4-tert-butylphenyl)pyridine), and [Au(C∧NTol∧C)(C≡CC 6H4-C6H13-p)] 9 (HC∧NTol∧ = 2,6-diphenyl-4-p-tolylpyridine), have been synthesized and characterized. The X-ray crystal structures of most of the complexes have also been determined. Electrochemical studies show that, in general, the first oxidation wave is an alkynyl ligand-centered oxidation, while the first reduction couple is ascribed to a ligand-centered reduction of the cyclometalated ligand with the exception of 3 in which the first reduction couple is assigned as an alkynyl ligand-centered reduction. Their electronic absorption and luminescence behaviors have also been investigated. In dichloromethane solution at room temperature, the low-energy absorption bands are assigned as the π-π* intraligand (IL) transition of the cyclometalated RC∧N(R′)∧CR ligand with some mixing of a [π(C≡CR″) → π*(RC∧N(R′)∧CR)] ligand-to-ligand charge transfer (LLCT) character. The low-energy emission bands of all the complexes, with the exception of 5, are ascribed to origins mainly derived from the π-π* IL transition of the cyclometalated RC∧N(R′)∧CR ligand. In the case of 5 that contains an electron-rich amino substituent on the alkynyl ligand, the low-energy emission band was found to show an obvious shift to the red. A change in the origin of emission is evident, and the emission of 5 is tentatively ascribed to a [π(C≡CC6H4NH 2) → π*(C∧N∧C)] LLCT excited-state origin. DFT and TDDFT computational studies have been performed to verify and elucidate the results of the electrochemical and photophysical studies.
