Visible-Light-Induced Photooxidation of Ruthenium(II) Complex with 2,2鈥?Biimidazole-like Ligand by Singlet Oxygen

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• 作者：Zheng-Zheng Li ; Yan-Li Niu ; Hai-Yun Zhou ; Hsiu-Yi Chao ; Bao-Hui Ye
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：September 3, 2013
• 年：2013
• 卷：52
• 期：17
• 页码：10087-10095
• 全文大小：479K
• 年卷期：v.52,no.17(September 3, 2013)
• ISSN：1520-510X

文摘

Four new ruthenium(II) complexes [Ru(bpy)₂(TMBiimH₂)](ClO₄)₂ (Ru-5; bpy is 2,2鈥?bipyridine and TMBiimH₂ is 4,5,4鈥?5鈥?tetramethyl-2,2鈥?biimidazole), [Ru(bpy)₂(L1H₂)](ClO₄)₂路H₂O (Ru-6; L1H₂ is 4,5-dimethyl-2-(N,N-diacetyl)carboximidamide-1H-imidazole), [Ru(bpy)₂(L2H₂)](ClO₄)₂ (Ru-7; L2H₂ is N¹,N¹,N²,N²-tetrakis(acetyl)ethanediimidamide), and [Ru(phen)₂(TMBiimH₂)](ClO₄)₂ (Ru-8; phen is 1,10鈥?phenanthroline) have been synthesized and characterized. Their photophysical and electrochemical properties have been studied and compared to the previously reported [Ru(bpy)₂(BiimH₂)](PF₆)₂ (Ru-1), [Ru(bpy)₂(BbimH₂)](PF₆)₂ (Ru-2), [Ru(bpy)₂(DMBbimH₂)](PF₆)₂ (Ru-3), and [Ru(bpy)₂(TMBbimH₂)](PF₆)₂ (Ru-4). Under irradiation with either sunlight or household light in atmosphere, Ru-5 reacts with molecular oxygen to produce Ru-6 in an acetonitrile solution with a relatively high concentration and Ru-7 in a methanol or dilute acetonitrile solution, respectively. The mechanism studies show that singlet oxygen is the reactive oxygen species in the ring-opening reaction and the photooxidation reaction is solvent- and concentration-dependent. The photoreaction product Ru-6 is an intermediate, which has been isolated and structurally characterized by single-crystal X-ray diffraction. Ru-6 is stable in the solid state and an acetonitrile solution with a high concentration, but can be further oxidized to Ru-7 in a methanol or dilute acetonitrile solution.