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Four luminescent cyclometalated iridium(Ⅲ) dipyridoquinoxaline complexes appended with an indole moiety [Ir(N^C)2(N^N)] (PF6) (HN^C = 2-phenylpyridine, Hppy; N^N = 2-(N-(2-(indole-3-acetamido)ethyl)aminocarbonyl)dipyrido[3,2-f:2′,3′-h]quinox- aline, dpqC2indole (1a), N^N = 2-(N-(6-(indole-3-acetamido)hexyl)aminocarbonyl)dipyrido[3,2-f:2′,3′-h]quinoxaline, dpqC6indole (1b); HN^C = 7,8-benzoquinoline, Hbzq, N^N = dpqC2indole (2a), N^N = dpqC6indole (2b)) have been synthesized and characterized. Upon irradiation, all the complexes displayed moderately intense and long-lived luminescence under ambient condi-tions and in 77 K glass. On the basis of the photophysical data, the emission of the complexes has been assigned to an excited state of triplet metal-to-ligand charge-transfer (3MLCT) ((dπ(Ir)→π*(N^N)) character. Cyclic voltammetric studies revealed indole-based and iridium-based oxidations at ca. +1.10 V and +1.24 V vs. SCE, respectively, and ligand-based reductions at ca. -1.07 to-2.29 V vs. SCE. The interactions of the complexes with an indole-binding protein, bovine serum albumin (BSA), have been examined by emission titrations.
Four luminescent cyclometalated iridium (Ⅲ) dipyridoquinoxaline complexes appended with an indole moiety [Ir (N ^ C) 2 (N ^ N)] (PF6) - (2- (indole-3-acetamido) ethyl) aminocarbonyl) dipyrido [3,2- f: 2 ’, 3’-h] quinoxaline, dpqC2 indole Hn ^ C = 7,8-benzoquinoline, Hbzq, N ^ (6-indole-3-acetamido) hexyl) dipyrido [3,2- f: 2 ’, 3’-h] quinoxaline, dpqC6indole N = dpqC2indole (2a), N ^ N = dpqC6indole (2b)) have been synthesized and characterized. Upon irradiation, all the complexes showed moderately intense intense and long- lived luminescence under ambient conditions and in 77 K glass. On the basis of the photophysical data, the emission of the complexes has been assigned to an excited state of triplet metal-to-ligand charge-transfer (3MLCT) (dπ (Ir) → π * (N ^ N)) character. Cyclic voltammetric studies revealed indole-based and iridium-based oxidations at ca. +1.10 V and +1.24 V vs. SCE, respectively, and ligand-based reductions at ca . -1.07 to-2.29 V vs. SCE. The interactions of the complexes with an indole-binding protein, bovine serum albumin (BSA), have been examined by emission titrations.