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首页> 外文期刊>Chemistry: A European journal >Catecholase activity of a copper(II) complex with a macrocyclic ligand: Unraveling catalytic mechanisms
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Catecholase activity of a copper(II) complex with a macrocyclic ligand: Unraveling catalytic mechanisms

机译：具有大环配体的铜（II）配合物的儿茶酚酶活性：揭示催化机理

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摘要

We report the structure, properties and a mechanism for the catecholase activity of a tetranuclear carbonato-bridged copper(II) cluster with the macrocyclic ligand [22]pr4pz (9,22-dipropyl-1,4,9,14,17,22,27,28,29, 30-decaazapentacyclo[22.2.1.1(4,7).1(11,14). 1(17,20)]triacontane-5,7(28),11(29),12,18, 20(30),24(27),25-octaene). In this complex, two copper ions within a macrocyclic unit are bridged by a carbonate anion, which further connects two macrocyclic units together. Magnetic susceptibility studies have shown the existence of a ferromagnetic interaction between the two copper ions within one macrocyclic ring, and a weak antiferromagnetic interaction between the two neighboring copper ions of two different macrocyclic units. The tetranuclear complex was found to be the major compound present in solution at high concentration levels, but its dissociation into two dinuclear units occurs upon dilution. The dinuclear complex catalyzes the oxidation of 3,5-di-tertbutylcatechol to the respective quinone in methanol by two different pathways, one proceeding via the formation of semiquinone species with the subsequent production of dihydrogen peroxide as a byproduct, and another proceeding via the two-electron reduction of the dicopper(II) center by the substrate, with two molecules of quinone and one molecule of water generated per one catalytic cycle. The occurrence of the first pathway was, however, found to cease shortly after the beginning of the catalytic reaction. The influence of hydrogen peroxide and ditert-butyl-o-benzoquinone on the catalytic mechanism has been investigated. The crystal structures of the free ligand and the reduced dicopper(I) complex, as well as the electrochemical properties of both the Cu-II and the Cu-I complexes are also reported.
机译：我们报告的结构，性质和机制的大环配体[22] pr4pz（9,22-dipropyl-1,4,9,14,17,22 ，27,28,29，30-十氮杂五环[22.2.1.1（4,7）.1（11,14）。1（17,20）]三aco烷-5,7（28），11（29），12， 18，20（30），24（27），25-辛烯）。在该络合物中，大环单元内的两个铜离子被碳酸根阴离子桥接，这进一步将两个大环单元连接在一起。磁化率研究表明，一个大环内两个铜离子之间存在铁磁相互作用，两个不同的大环单元的两个相邻铜离子之间存在弱的反铁磁相互作用。发现四核复合物是高浓度水平存在于溶液中的主要化合物，但稀释后会分解成两个双核单元。双核络合物通过两种不同的途径催化3,5-二叔丁基邻苯二酚在甲醇中氧化为相应的醌，一种途径是通过形成半醌类物质，随后产生副产物过氧化氢，另一种途径是通过两种-通过底物对双铜（II）中心进行电子还原，每个催化循环产生两分子的醌和一分子的水。然而，发现第一路径的发生在催化反应开始后不久就停止了。研究了过氧化氢和二叔丁基邻苯醌对催化机理的影响。还报道了游离配体和还原的双铜（I）配合物的晶体结构，以及Cu-II和Cu-I配合物的电化学性质。

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