Bedioui Fethi, Griveau Sophie, Nyokong Tebello, Appleby A John, Caro Claudia A, Gulppi Miguel, Ochoa Gonzalo, Zagal José H
INSERM, U 640, CNRS, UMR 8151, Ecole Nationale Supérieure de Chimie de Paris, René Descartes Paris 5, Chemical and Genetic Pharmacology Laboratory, Paris, France.
Phys Chem Chem Phys. 2007 Jul 14;9(26):3383-96. doi: 10.1039/b618767f. Epub 2007 Apr 11.
In this work we discuss different approaches for achieving electrodes modified with N(4) macrocyclic complexes for the catalysis of the electrochemical oxidation of thiols. These approaches involve adsorption, electropolymerization and molecular anchoring using self assembled monolayers. We also discuss the parameters that determine the reactivity of these complexes. Catalytic activity is associated with the nature of the central metal, redox potentials and Hammett parameters of substituents on the ligand. Correlations between catalytic activity (log i at constant E) and the redox potential of catalysts for complexes of Cr, Mn, Fe, Co, Ni and Cu are linear with an increase of activity for more positive redox potentials. For a great variety complexes bearing the same metal center (Co) correlations between log i and E(o') of the Co(II)/Co(I) couple have the shape of an unsymmetric volcano. This indicates that the potential of the Co(II)/Co(I) couple can be tuned using the appropriate ligand to achieve maximum catalytic activity. Maximum activity probably corresponds to a DeltaG of adsorption of the thiol on the Co center equal to zero, and to a coverage of active sites by the thiol equal to 0.5.
在这项工作中，我们讨论了制备用N(4)大环配合物修饰的电极以催化硫醇电化学氧化的不同方法。这些方法包括吸附、电聚合以及使用自组装单分子层的分子锚定。我们还讨论了决定这些配合物反应活性的参数。催化活性与中心金属的性质、配体上取代基的氧化还原电位和哈米特参数有关。对于Cr、Mn、Fe、Co、Ni和Cu的配合物，催化活性（在恒定E下的log i）与催化剂的氧化还原电位之间呈线性关系，氧化还原电位更正时活性增加。对于许多具有相同金属中心（Co）的配合物，log i与Co(II)/Co(I)电对的E(o')之间的相关性呈不对称火山形状。这表明可以使用合适的配体调节Co(II)/Co(I)电对的电位以实现最大催化活性。最大活性可能对应于硫醇在Co中心的吸附自由能ΔG等于零，以及硫醇对活性位点的覆盖度等于0.5。
