Influence of anionic co-ligands on the structural diversity and catecholase activity of copper(II) complexes with 2-methoxy-6-(8-iminoquinolinylmethyl)phenol
Influence of anionic co-ligands on the structural diversity and catecholase activity of copper(II) complexes with 2-methoxy-6-(8-iminoquinolinylmethyl)phenol
复制标题
阴离子辅助配体对铜(II)与2-甲氧基-6-(8-亚氨基喹啉基甲基)苯酚配合物结构多样性和儿茶酚酶活性的影响
作者：
Milan Shyamal;T. K. Mandal;A. Panja;A. Saha
以平面三齿配体2-甲氧基-6-（8-亚氨基喹啉基甲基）苯酚（HL）和假卤化物为配体，合成了新型双核铜（II）配合物[Cu2L2(μ1,1- n3)2](1)和单核铜（II）配合物[CuL(NCO)](2)，并用x射线晶体学测定了它们的固体结构。结构表征表明，在1中与中心对称相关的铜（II）中心的几何形状为方锥体，而在2中为方平面。发现了结构多样性对其儿茶酚氧化酶模拟活性的影响。强桥接叠氮化物离子具有取代惰性，意味着配合物1对儿茶酚酶活性无活性，而单核类似物2具有中等强度的儿茶酚氧化酶活性。配合物2和3,5- dtbch2混合物的ESI-MS正谱显示一个峰对应于超氧和底物结合的物质Na[CuL(O2)(3,5- dtbch2)]+，表明在催化循环中，双氧和底物同时配位到金属中心。最重要的是，配合物2不仅代表了单核铜（II）类化合物，这类化合物很少被用于儿茶酚酶模拟活性的研究，而且是单核方形平面配合物显示儿茶酚氧化酶活性的第一个例子。
A novel dinuclear copper(II) complex, [Cu2L2(μ1,1-N3)2] (1), and a mononuclear copper(II) complex, [CuL(NCO)] (2), have been synthesized from a planar tridentate ligand 2-methoxy-6-(8-iminoquinolinylmethyl)phenol (HL) together with pseudohalides as coligands, and the solid state structures were determined by X-ray crystallography. Structural characterizations reveal that the geometry of centrosymmetrically related copper(II) centers in 1 is square pyramidal while it is square planar in 2. The impact of the structural diversity was found on their catechol oxidase mimicking activity. Strongly bridging azide ions being substitutionally inert mean complex 1 is inactive towards the catecholase activity, while mononuclear analogue 2 exhibits moderately strong catechol oxidase activity. The ESI-MS positive spectrum of a mixture of complex 2 and 3,5-DTBCH2 shows a peak corresponding to both superoxo and substrate bound species, Na[CuL(O2)(3,5-DTBCH)]+, suggesting that both the dioxygen and substrate simultaneously coordinated to the metal center in the catalytic cycle. Most importantly, complex 2 not only represents the mononuclear class of copper(II) compounds that are rarely visited for the study of catecholase mimicking activity but also the first example of a mononuclear square planar complex exhibiting catechol oxidase activity.