Electrochemical and Electrogenerated Chemiluminescent Studies of a Trinuclear Complex, [((phen)2Ru(dpp))2RhCl2]5+, and Its Interactions with Calf Thymus DNA

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• 作者：Shijun Wang ; Jenifer Milam ; André ; C. Ohlin ; Varma H. Rambaran ; Eva Clark ; Woodrow Ward ; Luke Seymour ; William H. Casey ; Alvin A. Holder ; Wujian Miao
• 刊名：Analytical Chemistry
• 出版年：2009
• 出版时间：May 15, 2009
• 年：2009
• 卷：81
• 期：10
• 页码：4068-4075
• 全文大小：240K
• 年卷期：v.81,no.10(May 15, 2009)
• ISSN：1520-6882

文摘

The electrochemical behavior of a trinuclear ruthenium(II)-containing complex, [((phen)₂Ru(dpp))₂RhCl₂]⁵⁺ (where phen = 1,10-phenanthroline, dpp = 2,3-bis(2-pyridyl)pyrazine), was studied in acetonitrile (MeCN) and aqueous solutions. In MeCN containing 0.10 M tetra-n-butylammonium perchlorate (TBAP), the complex displayed a reversible, overlapping Ru^II/III redox process with E_1/2 = +1.21 V vs Ag/Ag⁺ (10 mM), an irreversible reduction of Rh^III/I at −0.73 V vs Ag/Ag⁺, and two quasi-reversible dpp/dpp⁻ couples with E_1/2 = −1.11 and −1.36 V vs Ag/Ag⁺ at a Pt electrode with a scan rate of 50 mV s⁻¹. In 0.20 M Tris buffer solution (pH 7.4), an irreversible, overlapping Ru^II/III oxidation at +1.48 V vs Ag/AgCl (3 M KCl), and an irreversible reduction of Rh^III/II at −0.78 V vs Ag/AgCl were observed at a glassy carbon electrode with a scan rate of 50 mV/s. Investigations on the electrogenerated chemiluminescence (ECL) of the complex revealed that 2-(dibutylamino) ethanol (DBAE) was superior to tri-n-propylamine (TPrA) as an ECL coreactant within their entire concentration range of 10−100 mM in MeCN, and in aqueous media, as low as 1.0 nM of the complex can be detected using TPrA coreactant ECL. A maximum ECL emission of 640 nm, which is about 55 nm blue shift to its fluorescence, was observed in MeCN with DBAE as a coreactant. Interactions of the complex with calf thymus DNA (ctDNA) were conducted with a flow-cell based quartz-crystal microbalance, and a binding constant of 2.5 × 10⁵ M⁻¹ was calculated on the basis of the Langmuir isotherm equation.