Unusual Photophysical Properties of a Ruthenium(II) Complex Related to [Ru(bpy)2(dppz)]2+

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• 作者：Yujie Sun ; Sibrina N. Collins ; Lauren E. Joyce ; Claudia Turro
• 刊名：Inorganic Chemistry
• 出版年：2010
• 出版时间：May 3, 2010
• 年：2010
• 卷：49
• 期：9
• 页码：4257-4262
• 全文大小：743K
• 年卷期：v.49,no.9(May 3, 2010)
• ISSN：1520-510X

文摘

A new ruthenium polypyridyl complex, [Ru(bpy)₂(dpqp)]²⁺ (bpy = 2,2′-bipyridne; dpqp = pyrazino[2′,3′:5,6]pyrazino[2,3-f][1,10]phenanthroline), shows strong luminescence in water at room temperature, a behavior that is strikingly different from that of the nonemissive “DNA light-switch” prototype [Ru(bpy)₂(dppz)]²⁺ (dppz = dipyrido[3,2-a:2′-3′-c]phenazine) under similar conditions. Variation of the absorption and emission spectra of [Ru(bpy)₂(dpqp)]²⁺ as a function of the pH is consistent with the occurrence of two ground-state protonation steps associated with the dpqp ligand and an apparent pK_a* of 2.1. Electrochemistry and theoretical calculations indicate that the lowest unoccupied molecular orbital (LUMO) of [Ru(bpy)₂(dpqp)]²⁺ is localized on the distal portion of the dpqp ligand and lies at a lower energy than the dppz-based LUMO of [Ru(bpy)₂(dppz)]²⁺. The combination of its strong DNA binding affinity and relatively long-lived triplet metal-to-ligand charge-transfer excited state in an aqueous solution results in more efficient DNA photocleavage by [Ru(bpy)₂(dpqp)]²⁺ than [Ru(bpy)₂(dppz)]²⁺.