Gout Jérôme, Višnjevac Aleksandar, Rat Stéphanie, Parrot Arnaud, Hessani Assia, Bistri Olivia, Le Poul Nicolas, Le Mest Yves, Reinaud Olivia
Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques, Sorbonne Paris Cité, Université Paris Descartes, CNRS UMR 8601 , 45 Rue des Saints Pères, 75006 Paris, France.
Inorg Chem. 2014 Jun 16;53(12):6224-34. doi: 10.1021/ic500740r. Epub 2014 Jun 5.
Modeling the mononuclear site of copper enzymes is important for a better understanding of the factors controlling the reactivity of the metal center. A major difficulty stems from the difficult control of the nuclearity while maintaining free sites open to coordination of exogenous ligands. A supramolecular approach consists in associating a hydrophobic cavity to a tripodal ligand that will define the coordination spheres as well as access to the metal ion. Here, we describe the synthesis of a bowl Cu(II) complex based on the resorcinarene scaffold. This study supplements a previous work on Cu(I) coordination. It provides a complete picture of the cavity-copper system in its two oxidation states. The first XRD structure of such a bowl complex was obtained, evidencing a 5-coordinate Cu(II) ion with the three imidazole donors bound to the metal (two in the base of the pyramid, one in the apical position) and with an acetate anion, completing the base of the pyramid, and deeply included in the bowl. Solution studies conducted by EPR and UV-vis absorption spectroscopies as well as cyclic voltammetry highlighted interaction with coordinating solvents, various carboxylates that can sit either in the endo or in the exo position depending on their size as well as possible stabilization of hydroxo species in a mononuclear state. A comparison of the binding and redox properties of the bowl complex with funnel complexes based on the calix[6]arene core further highlights the importance of supramolecular features defining the first, second, and third coordination sphere for control of the metal ion.
对铜酶单核位点进行建模，对于更好地理解控制金属中心反应性的因素至关重要。一个主要困难在于，在保持游离位点可供外源配体配位的同时，难以控制核数。一种超分子方法是将一个疏水腔与一个三脚架配体相结合，该三脚架配体将定义配位球以及金属离子的可及性。在此，我们描述了一种基于间苯二酚杯芳烃支架的碗状铜（II）配合物的合成。这项研究补充了之前关于铜（I）配位的工作。它提供了处于两种氧化态的腔 - 铜体系的完整图景。获得了这种碗状配合物的首个X射线衍射结构，证明了一个五配位的铜（II）离子，其中三个咪唑供体与金属配位（两个在金字塔底部，一个在顶端位置），还有一个醋酸根阴离子，构成金字塔底部，并深深包含在碗状结构中。通过电子顺磁共振和紫外 - 可见吸收光谱以及循环伏安法进行的溶液研究突出了与配位溶剂的相互作用、各种羧酸盐的情况，这些羧酸盐根据其大小可处于内位或外位，以及单核状态下羟基物种可能的稳定化。将该碗状配合物与基于杯[6]芳烃核的漏斗状配合物的结合和氧化还原性质进行比较，进一步突出了定义第一、第二和第三配位球的超分子特征对于控制金属离子的重要性。
