A mechanistic study of the dynamic quenching of the excited state of europium(III) and terbium(III) macrocyclic complexes by charge- or electron transfer
A mechanistic study of the dynamic quenching of the excited state of europium(III) and terbium(III) macrocyclic complexes by charge- or electron transfer
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DOI：
10.1039/b709062e
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发表时间：
2007-01-01
影响因子：
3.2
通讯作者：
Stenson, Philip A.
中科院分区：
文献类型：
--
作者：
Kielar, Filip;Montgomery, Craig P.;Stenson, Philip A.
本文研究了十六种不同大环配体的Eu（Ⅲ）和Tb（Ⅲ）配合物的金属基激发态的动态猝灭。通过尿酸盐、抗坏血酸盐和选择的儿茶酚的淬灭对于Tb（III）系统是最有效的，并且涉及在结合到配体（四氮杂苯并菲、氮杂蒽酮或邻苯二甲酰-氮杂蒽酮）中的贫电子杂环敏化部分和富电子还原剂之间的激发态络合物（激基复合物）的中间体形成。该过程是敏感的局部配体环境所产生的空间位阻，淬火减少温度升高激基复合物的形成是熵不利的。相比之下，根据经典碰撞碰撞模型，碘会猝灭所研究的每个复合物;升高温度会提高猝灭速率，并且该过程对配体取代产生的局部静电场更加敏感，符合传统的斯特恩-沃尔默动力学模型。淬灭可以通过蛋白质缔合来抑制，从而允许鉴定用作光学成像的候选物。
Dynamic quenching of the metal-based excited state of Eu(III) and Tb(III) complexes of sixteen different macrocyclic ligands has been studied. Quenching by urate, ascorbate and selected catechols is most effective for Tb( III) systems, and involves intermediate formation of an excited state complex (exciplex) between the electron-poor heterocyclic sensitising moiety incorporated into the ligand ( tetraazatriphenylene, azaxanthone or a pyrazoyl-azaxanthone) and the electron-rich reductant. The process is sensitive to steric inhibition created by the local ligand environment; quenching is reduced as temperature increases as exciplex formation is entropically disfavoured. In contrast, iodide quenches each complex studied according to a classical collisional encounter model; increasing temperature enhances the rate of quenching, and the process is more sensitive to local electrostatic fields generated by ligand substitution, conforming to a traditional Stern-Volmer kinetic model. Quenching may be inhibited by protein association, allowing the identification of candidates for use as optical imaging