Laboratoire d'Electrochimie Physique et Analytique, Ecole Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland.
J Am Chem Soc. 2010 Oct 6;132(39):13733-41. doi: 10.1021/ja103460p.
The diprotonated form of a fluorinated free base porphyrin, namely 5-(p-aminophenyl)-10,15,20-tris(pentafluorophenyl)porphyrin (H(2)FAP), can catalyze the reduction of oxygen by a weak electron donor, namely ferrocene (Fc). At a water/1,2-dichloroethane interface, the interfacial formation of H(4)FAP(2+) is observed by UV-vis spectroscopy and ion-transfer voltammetry, due to the double protonation of H(2)FAP at the imino nitrogen atoms in the tetrapyrrole ring. H(4)FAP(2+) is shown to bind oxygen, and the complex in the organic phase can easily be reduced by Fc to produce hydrogen peroxide as studied by two-phase reactions with the Galvani potential difference between the two phases being controlled by the partition of a common ion. Spectrophotometric measurements performed in 1,2-dichloroethane solutions clearly evidence that reduction of oxygen by Fc catalyzed by H(4)FAP(2+) only occurs in the presence of the tetrakis(pentafluorophenyl)borate (TB(-)) counteranion in the organic phase. Finally, ab initio computations support the catalytic activation of H(4)FAP(2+) on oxygen.
氟代自由碱基卟啉的二质子化形式，即 5-(对氨基苯基)-10,15,20-三(五氟苯基)卟啉（H(2)FAP），可以催化弱电子供体，即二茂铁（Fc）还原氧。在水/1,2-二氯乙烷界面，通过紫外可见光谱和离子转移伏安法观察到 H(4)FAP(2+)的界面形成，这是由于 H(2)FAP 在卟啉环的亚氨基氮原子上的双重质子化。H(4)FAP(2+)被证明可以结合氧，并且通过两相反应研究表明，有机相中的配合物很容易被 Fc 还原为过氧化氢，两相之间的 Galvani 电位差由常见离子的分配控制。在 1,2-二氯乙烷溶液中进行的分光光度测量清楚地表明，只有在有机相中存在四(五氟苯基)硼酸盐（TB(-)）反离子时，H(4)FAP(2+)催化 Fc 还原氧才会发生。最后，从头算计算支持 H(4)FAP(2+)对氧的催化活化。
