Laboratório de Bioinorgânica e Crystalografia (LABINC), Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina, Brazil.
Inorg Chem. 2012 Feb 6;51(3):1569-89. doi: 10.1021/ic201876k. Epub 2012 Jan 19.
Herein, we report the synthesis and characterization, through elemental analysis, electronic spectroscopy, electrochemistry, potentiometric titration, electron paramagnetic resonance, and magnetochemistry, of two dinuclear copper(II) complexes, using the unsymmetrical ligands N',N',N-tris(2-pyridylmethyl)-N-(2-hydroxy-3,5-di-tert-butylbenzyl)-1,3-propanediamin-2-ol (L1) and N',N'-bis(2-pyridylmethyl)-N,N-(2-hydroxybenzyl)(2-hydroxy-3,5-di-tert-butylbenzyl)-1,3-propanediamin-2-ol (L2). The structures of the complexes Cu(2)(L1)(μ-OAc)(2)·(CH(3))(2)CHOH (1) and Cu(2)(L2)(μ-OAc)·H(2)O·(CH(3))(2)CHOH (2) were determined by X-ray crystallography. The complex Cu(2)(L3)(μ-OAc) [3; L3 = N-(2-hydroxybenzyl)-N',N',N-tris(2-pyridylmethyl)-1,3-propanediamin-2-ol] was included in this study for comparison purposes only (Neves et al. Inorg. Chim. Acta2005, 358, 1807-1822). Magnetic data show that the Cu(II) centers in 1 and 2 are antiferromagnetically coupled and that the difference in the exchange coupling J found for these complexes (J = -4.3 cm(-1) for 1 and J = -40.0 cm(-1) for 2) is a function of the Cu-O-Cu bridging angle. In addition, 1 and 2 were tested as catalysts in the oxidation of the model substrate 3,5-di-tert-butylcatechol and can be considered as functional models for catechol oxidase. Because these complexes possess labile sites in their structures and in solution they have a potential nucleophile constituted by a terminal Cu(II)-bound hydroxo group, their activity toward hydrolysis of the model substrate 2,4-bis(dinitrophenyl)phosphate and DNA was also investigated. Double electrophilic activation of the phosphodiester by monodentate coordination to the Cu(II) center that contains the phenol group with tert-butyl substituents and hydrogen bonding of the protonated phenol with the phosphate O atom are proposed to increase the hydrolase activity (K(ass.) and k(cat.)) of 1 and 2 in comparison with that found for complex 3. In fact, complexes 1 and 2 show both oxidoreductase and hydrolase/nuclease activities and can thus be regarded as man-made models for studying catalytic promiscuity.
本文通过元素分析、电子光谱、电化学、电位滴定、电子顺磁共振和磁化学，报道了两种双核铜（II）配合物的合成和表征，使用的不对称配体为 N'，N'，N'-三（2-吡啶甲基）-N-（2-羟基-3,5-二叔丁基苄基）-1,3-丙二胺-2-醇（L1）和 N'，N'-双（2-吡啶甲基）-N,N' -（2-羟基苄基）（2-羟基-3,5-二叔丁基苄基）-1,3-丙二胺-2-醇（L2）。配合物[Cu2（L1）（μ-OAc）]（ClO4）（2）·（CH3）2CHOH（1）和[Cu2（L2）（μ-OAc）]（ClO4）·H2O·（CH3）2CHOH（2）的结构通过 X 射线晶体学确定。为了比较的目的，仅包括配合物[Cu2（L3）（μ-OAc）]（2+）[3; L3 = N-（2-羟基苄基）-N'，N'，N'-三（2-吡啶甲基）-1,3-丙二胺-2-醇]（Neves 等人。无机化学学报 2005, 358, 1807-1822）。磁数据表明，1 和 2 中的 Cu（II）中心呈反铁磁耦合，对于这些配合物发现的交换耦合 J 的差异（J = -4.3 cm-1 对于 1 和 J = -40.0 cm-1 对于 2）是 Cu-O-Cu 桥接角的函数。此外，1 和 2 被测试为模型底物 3,5-二叔丁基儿茶酚氧化的催化剂，并且可以被认为是儿茶酚氧化酶的功能模型。由于这些配合物在其结构中和溶液中具有不稳定的位点，并且具有末端 Cu（II）结合的羟基金属配体，因此还研究了它们对模型底物 2,4-双（二硝基苯基）磷酸盐和 DNA 的水解的活性。通过单齿配位到含有叔丁基取代基的酚基团的 Cu（II）中心的双亲电磷酸二酯的激活和质子化酚与磷酸 O 原子的氢键被提出以增加水解酶活性（K（ass.）和 k（cat.））与配合物 3 相比，1 和 2。事实上，配合物 1 和 2 均显示氧化还原酶和水解酶/核酸酶活性，因此可以被视为研究催化混杂性的人工模型。
