Devaraj Neal K, Decreau Richard A, Ebina Wataru, Collman James P, Chidsey Christopher E D
Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA.
J Phys Chem B. 2006 Aug 17;110(32):15955-62. doi: 10.1021/jp057416p.
The rate of electron transfer is measured to two ferrocene and one iron tetraphenylporphyrin redox species coupled through terminal acetylenes to azide-terminated thiol monolayers by the Cu(I)-catalyzed azide-alkyne cycloaddition (a Sharpless "click" reaction) to form the 1,2,3-triazole linkage. The high yield, chemoselectivity, convenience, and broad applicability of this triazole formation reaction make such a modular assembly strategy very attractive. Electron-transfer rate constants from greater than 60,000 to 1 s(-1) are obtained by varying the length and conjugation of the electron-transfer bridge and by varying the surrounding diluent thiols in the monolayer. Triazole and the triazole carbonyl linkages provide similar electronic coupling for electron transfer as esters. The ability to vary the rate of electron transfer to many different redox species over many orders of magnitude by using modular coupling chemistry provides a convenient way to study and control the delivery of electrons to multielectron redox catalysts and similar interfacial systems that require controlled delivery of electrons.
通过铜（I）催化的叠氮化物-炔烃环加成反应（一种夏普莱斯“点击”反应），将两个二茂铁和一个四苯基卟啉铁氧化还原物种通过末端乙炔与叠氮基封端的硫醇单分子层偶联，形成1,2,3-三唑连接，以此来测量电子转移速率。这种三唑形成反应的高产率、化学选择性、便利性和广泛适用性使得这种模块化组装策略非常具有吸引力。通过改变电子转移桥的长度和共轭性以及单分子层中周围的稀释硫醇，可获得大于60,000至1 s(-1)的电子转移速率常数。三唑和三唑羰基连接为电子转移提供了与酯类似的电子耦合。通过使用模块化偶联化学方法，能够在多个数量级上改变向许多不同氧化还原物种的电子转移速率，这为研究和控制向多电子氧化还原催化剂以及需要可控电子传递的类似界面系统的电子传递提供了一种便捷的方式。
