Pfister Tim, Söhnel Tilo, Collins Terrence J, Wright L James
School of Chemical Sciences and, Centre for Green Chemical Science, University of Auckland, 23 Symonds St, Auckland, 1010, New Zealand.
Institute for Green Science, Department of Chemistry, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, PA 15213, USA.
Chemistry. 2023 Dec 11;29(69):e202301548. doi: 10.1002/chem.202301548. Epub 2023 Oct 27.
The macrocyclic proligand [H L][OTf] , which contains four carboxamide functions and two conjugated pyridinium groups, is easily deprotonated by the weak base sodium acetate to give the corresponding neutral proligand [H L]. Metallation of [H L] with iron(II) chloride proceeds rapidly to form the macrocyclic complex, [Fe Cl(L)]. This is an effective catalyst for the oxidation of the organic dye orange II by hydrogen peroxide in aqueous solution, and the kinetic parameters for this reaction have been determined. In striking contrast to an analogous iron-TAML complex that contains two phenyl groups in place of the two pyridinium groups, [Fe Cl(L)] is a very active oxidation catalyst at pH 7 and is also highly stable towards acid-promoted demetallation at pH 5 or above. The results show that the two pyridinium groups bring greatly enhanced catalytic properties to [Fe Cl(L)].
大环前体配体[H L][OTf]含有四个羧酰胺官能团和两个共轭吡啶鎓基团，很容易被弱碱醋酸钠去质子化，生成相应的中性前体配体[H L]。[H L]与氯化亚铁进行金属化反应迅速形成大环配合物[Fe Cl(L)]。这是一种在水溶液中用过氧化氢氧化有机染料橙II的有效催化剂，并且已经测定了该反应的动力学参数。与一个类似的铁 - TAML配合物形成鲜明对比的是，该类似物含有两个苯基取代两个吡啶鎓基团，[Fe Cl(L)]在pH为7时是一种非常活跃的氧化催化剂，并且在pH为5或更高时对酸促进的脱金属作用也高度稳定。结果表明，两个吡啶鎓基团极大地增强了[Fe Cl(L)]的催化性能。
