Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302, India.
Dalton Trans. 2019 Jan 22;48(4):1292-1313. doi: 10.1039/c8dt04183k.
Rational ligand design approaches allowed {Cu2(μ-OH/OMe)} cores to be accommodated within μ-phenoxido bis(tetradentate) and μ-phenoxido bis(tridentate) ligands having thioether donors. The complexes Cu2(μ-H2L1)(μ-OH)2·2H2O (1), Cu2(μ-L2)(μ-OH)(OH2)2 (2a) and Cu2(μ-L2)(μ-OCH3)(OH2)2 (2b) were obtained from an N2O3S2 donor set bearing the H3L1 ligand (2,6-bis-[{2-(2-hydroxyethylthio)ethylimino}methyl]-4-methylphenol) and N2OS2 donor set containing the HL2 ligand (4-methyl-2,6-bis-[{2-(methylthio)phenylimino}methyl]phenol) without showing double phenoxido bridging or any type of preformed inter-fragment aggregation. Previously, we showed that H3L (2,6-bis[((2-(2-hydroxyethoxy)ethyl)imino)methyl]-4-methylphenol), the ether analogue of H3L1, in the presence of carboxylate anions, was responsible for the self-aggregation of preformed {Cu2} fragments and gave two types of [Cu4] complexes comprising [Cu4O] and [Cu4(OH)2] cores (T. S. Mahapatra, A. Bauzá, D. Dutta, S. Mishra, A. Frontera and D. Ray, ChemistrySelect, 2016, 1, 64-74). The molecular structures of 1, 2a and 2b were determined via single crystal X-ray diffraction and solution studies, which indicated the presence of [Cu2] species. This was further confirmed via UV-vis spectroscopy and HRMS analysis. The synthesized complexes were screened for their potential as catalysts for the catalytic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBCH2). A change in the mechanism of catalytic oxidation was observed with a change in the ligand backbone. All three complexes also showed DNA binding properties, which were further substantiated via molecular docking studies. Their DNA binding affinities were quantitatively ascertained using their intrinsic binding constant, Kb, values which were found to be 4.2 × 104, 5.6 × 104 and 4.8 × 104 M-1, respectively. Furthermore, the complexes displayed efficient DNA cleavage behaviour with pBR322 and the oxidative path was established in presence of ROS, singlet oxygen, 1O2, and the superoxide anion, O2·-.
合理的配体设计方法允许将 {Cu2(μ-OH/OMe)} 核容纳在具有硫醚供体的 μ-苯氧双（四齿）和 μ-苯氧双（三齿）配体中。从具有 H3L1 配体（2,6-双-[{2-（2-羟乙基硫代）乙基亚氨基}甲基]-4-甲基苯酚）和 HL2 配体（4-甲基-2,6-双-[{2-（甲基硫代）苯基亚氨基}甲基]苯酚）的 N2O3S2 供体组和 N2OS2 供体组中获得了 Cu2(μ-H2L1)(μ-OH)2·2H2O（1）、Cu2(μ-L2)(μ-OH)(OH2)2（2a）和 Cu2(μ-L2)(μ-OCH3)(OH2)2（2b）复合物，而没有显示出双苯氧桥接或任何类型的预形成片段聚集。此前，我们表明，H3L（2,6-双[（2-（2-羟乙氧基）乙基）亚氨基）甲基]-4-甲基苯酚），H3L1 的醚类似物，在存在羧酸根阴离子的情况下，负责预形成的 {Cu2} 片段的自聚集，并给出了两种类型的 [Cu4] 配合物，包括 [Cu4O] 和 [Cu4(OH)2] 核（T. S. Mahapatra、A. Bauzá、D. Dutta、S. Mishra、A. Frontera 和 D. Ray，ChemistrySelect，2016，1，64-74）。通过单晶 X 射线衍射和溶液研究确定了 1、2a 和 2b 的分子结构，表明存在 [Cu2] 物种。这通过紫外-可见光谱和高分辨率质谱分析进一步得到证实。合成的配合物被筛选用于催化 3,5-二叔丁基儿茶酚（3,5-DTBCH2）的催化氧化的潜在用途。配体骨架的变化导致催化氧化机制发生变化。所有三种配合物都显示出 DNA 结合特性，这通过分子对接研究进一步得到证实。使用它们的固有结合常数 Kb 值定量确定了它们的 DNA 结合亲和力，发现分别为 4.2×104、5.6×104 和 4.8×104 M-1。此外，这些配合物显示出与 pBR322 有效的 DNA 切割行为，并且在 ROS、单线态氧 1O2 和超氧阴离子 O2·-存在下建立了氧化途径。
