期刊
JOURNAL OF MOLECULAR STRUCTURE
卷 1035, 期 -, 页码 224-230出版社
ELSEVIER
DOI: 10.1016/j.molstruc.2012.11.015
关键词
Iridium complex; Electrochemistry; Electrochemiluminescence (ECL); Density functional theory (DFT)
资金
- National Natural Science Foundation of China [21175060, 20971058]
- Key Projects in Science & Technology Pillar Program of Jiangsu Province, China [BE2010115]
The electrochemical and electrochemiluminescent (ECL) properties of six bis-cyclometalated iridium(III) complexes (ppy)(2)Ir(N-phenylacetamide) (1), (ppy)(2)Ir(N-phenylbenzamide) (2), (ppy)(2)Ir(N-naphthylbenzamide) (3), (ppy)2Ir(N-phenylmethacrylamide) (4), (pq)(2)Ir(N-phenylmethacrylamide) (5) and (pq)(2-)Ir(acac) (6) were studied in acetonitrile, where ppy is phenylpyridine anion, pq is phenylquinoline anion and acac is acetylacetone anion. These complexes exhibited quasi-reversible one-electron oxidation waves with the oxidation potentials varied from 0.95 to 1.51 V (vs. SCE) and the first irreversible reduction peaks fell into the range of -1.58 to -1.86 V. The effects of the different ligands on the redox potentials and electrochemical reversibility were elucidated by the energies and compositions of the frontier orbitals. The relative ECL efficiencies of the complexes 1-6 were 0.032, 0.020, 0.014, 0.041, 0.11 and 26.0 respectively when referenced to Ru(bpy)(3)(2+) and the differences in ECL efficiency were rationalized by the density functional theory (DFT) calculations. The energy gap between the lowest unoccupied molecular orbital (LUMO) of anodic product (M+.) and the deprotonated product (TPA(.)) determined the electron transfer efficiency to generate the excited states. Other factors such as the lifetime of the radical intermediates, the oxidation potential gaps between the M and TPA, the amount of M+. generation and the luminescence efficiency (Phi(em)) were also considered in comparison of different ECL systems. (c) 2012 Elsevier B.V. All rights reserved.
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