水性缓冲溶液中儿茶酚/邻醌氧化还原偶的超快光谱电化学研究

IF 3 4区 化学 Q3 CHEMISTRY, PHYSICAL
Sofia Goia, Gareth W. Richings, Matthew A. P. Turner, Jack M. Woolley, Joshua J. Tully, Samuel J. Cobb, Adam Burriss, Ben R. Robinson, Julie V. Macpherson, Vasilios G. Stavros
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引用次数: 0

摘要

乌黑色素是一种存在于许多生物体内的天然色素,它能抵御有害的紫外线辐射。作为一种具有氧化还原活性的生物聚合物,乌黑色素的结构被认为包含不同氧化还原态的醌,包括儿茶酚亚基。为了进一步探究乌梅素的激发态特性,我们在 pH 值为 7.4 的缓冲水溶液中使用掺硼金刚石网状电极,通过光谱电化学方法研究了儿茶酚/邻醌氧化还原对。在 pH 值为 7.4 时,促进了儿茶酚的双质子、双电子氧化作用,从而促进了溶液中不稳定的邻醌产物的持续形成。邻醌物种的超快瞬态吸收(飞秒到纳秒)测量涉及激发单线态的初始形成,随后在 24 ps 内形成三线态。相反,儿茶酚在水缓冲液中会形成半醌自由基 Δt > 500 ps。我们的研究结果证明了儿茶酚/邻醌氧化还原偶联物丰富的光化学性质,并进一步揭示了这些乌梅素关键结构单元的激发态过程。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Ultrafast Spectroelectrochemistry of the Catechol/o-Quinone Redox Couple in Aqueous Buffer Solution

Ultrafast Spectroelectrochemistry of the Catechol/o-Quinone Redox Couple in Aqueous Buffer Solution

Eumelanin is a natural pigment found in many organisms that provides photoprotection from harmful UV radiation. As a redox-active biopolymer, the structure of eumelanin is thought to contain different redox states of quinone, including catechol subunits. To further explore the excited state properties of eumelanin, we have investigated the catechol/o-quinone redox couple by spectroelectrochemical means, in a pH 7.4 aqueous buffered solution, and using a boron doped diamond mesh electrode. At pH 7.4, the two proton, two electron oxidation of catechol is promoted, which facilitates continuous formation of the unstable o-quinone product in solution. Ultrafast transient absorption (femtosecond to nanosecond) measurements of o-quinone species involve initial formation of an excited singlet state followed by triplet state formation within 24 ps. In contrast, catechol in aqueous buffer leads to formation of the semiquinone radical Δt>500 ps. Our results demonstrate the rich photochemistry of the catechol/o-quinone redox couple and provides further insight into the excited state processes of these key building blocks of eumelanin.

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来源期刊
ChemPhotoChem
ChemPhotoChem Chemistry-Physical and Theoretical Chemistry
CiteScore
5.80
自引率
5.40%
发文量
165
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