Abstract We report the biological activity of the new Schiff base ligand H2L (H2L = 6,6′-((1E,11E)-5,8-dioxa-2,11-diazadodeca-1,11-diene-1,12-diyl)bis(2,4-dichlorophenol)), its derived metal(II) complexes [Cu(L)] (1), [Co(L)] (2), [Ni(L)] (3) and [Zn(L)] (4), along with their structural characterizations by using various analytical and spectroscopic techniques. Electrochemical investigations showed that all of these Cu(II), Co(II) and Ni(II) complexes were reversibly reducible. Although the change of the number of unpaired electrons are different of the metal cations, they have an effect on the redox potentials of the Co(II)/(I), Ni(II)/(I) and Cu(II)/(I) couples. The 1H NMR and FTIR data concluded that the Schiff base ligand H2L acts as a hexadentate ligand coordinating with metal(II) ions through the oxygen atoms of the ( C O C), phenolic ( C OH) groups and nitrogen atom of the azomethine ( CH N ) group. UV-Visible absorption spectra studies clearly revealed the octahedral geometry of the prepared metal(II) complexes. Complexes 1 and 4 were found to be efficient in bringing about antimicrobial activities. The proposed mechanism of their antimicrobial activities has been discussed. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed the remarkable cytotoxicity of complex 1 (IC50 = 17 ± 1.3 μg/mL) on human breast cancer MCF-7 cells than Schiff base ligand H2L and complexes 2–4. Moreover, AO/EB staining assay revealed cell death due to apoptosis in MCF-7 cells and the generation of ROS by the Schiff base ligand H2L and its derived metal(II) complexes 1–4 may be a possible cause for their cytotoxic activity.

中文翻译：

---

包含 N2O4 供体六齿席夫碱配体的新型金属 (II) 配合物的光谱表征、电化学、抗菌和细胞毒性研究

摘要 我们报告了新的希夫碱配体 H2L (H2L = 6,6'-((1E,11E)-5,8-dioxa-2,11-diazadodeca-1,11-diene-1,12-) 的生物活性二基）双（2,4-二氯苯酚）），其衍生的金属（II）配合物 [Cu(L)] (1), [Co(L)] (2), [Ni(L)] (3) 和 [ Zn(L)] (4) 及其使用各种分析和光谱技术的结构表征。电化学研究表明，所有这些 Cu(II)、Co(II) 和 Ni(II) 配合物都是可逆还原的。虽然不成对电子数的变化与金属阳离子不同，但它们对 Co(II)/(I)、Ni(II)/(I) 和 Cu(II)/(我）夫妇。1H NMR 和 FTIR 数据得出结论，席夫碱配体 H2L 作为六齿配体通过 (COC) 的氧原子与金属 (II) 离子配位，苯酚 (C OH) 基团和偶氮甲碱 (CH N) 基团的氮原子。紫外-可见吸收光谱研究清楚地揭示了所制备的金属 (II) 配合物的八面体几何形状。发现复合物 1 和 4 在产生抗微生物活性方面是有效的。已经讨论了它们抗微生物活性的拟议机制。3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) 测定显示复合物 1 (IC50 = 17 ± 1.3 μg/mL) 对人乳腺癌 MCF-7 细胞的显着细胞毒性比席夫碱配体 H2L 和配合物 2-4。此外，AO/EB 染色分析显示 MCF-7 细胞凋亡导致细胞死亡，席夫碱配体 H2L 及其衍生的金属（II）配合物 1-4 产生的 ROS 可能是其细胞毒活性的可能原因。