Catalytic Cooperativity, Nuclearity, and O
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Specificity of Multi‐Copper(II) Complexes of Cyclen‐Tethered Cyclotriphosphazene Ligands in Aqueous Media
作者:Le Wang、Yong Ye、Vasiliki Lykourinou、Junliang Yang、Alexander Angerhofer、Yufen Zhao、Li‐June Ming
DOI:10.1002/ejic.201700811
日期:2017.11.16
Three ligands L1, L2, and L3 with 2, 4, and 6 1,4,7,10‐tetraazacyclododecane (cyclen) moieties attached to a cyclotriphosphazene core, respectively, were synthesized, and oxidation activities of their CuII complexes were investigated. Aerobic oxidation of catechol by these complexes follows an intramolecular dinuclear pathway with significant cooperativity (i.e., θ ≈ 1.5 out of a maximum of 2 for two
分别合成了三个分别带有2、4和6个1,4,7,10-四氮杂环十二烷(环)的配体L1,L2和L3,并研究了其Cu II配合物的氧化活性。这些复合物的邻苯二酚有氧氧化遵循分子内双核途径,具有显着的协同作用(即,对于两个潜在的底物结合位点,θ≈1.5,最大值为2)和动力学常数(即,k cat = 17.5×10 –3 s – 1,K m = 2.8毫米,并且每个二铜中心的催化特异性为k cat / K m 12.5 m –1 s –1,非常显着,而不受束缚的Cu II –cycln的催化特异性遵循双分子双核途径,没有明显的协同性(θ = 0.96),并且k值低四倍猫,尽管它们具有类似的双核机制。EPR光谱和弛豫表明Cu II中心的接近,显示出较宽的光谱成分,尤其是在Cu 6 L3中。热力学参数还表明了多铜II的重要性位在氧化催化中。空气是典型的复合物Cu 2 L1的更具体的氧化剂,对儿茶酚底物的催化特异性k