Here, we synthesized novel chelation-free Zn(II)-complexes (1-3) [ZnCl₂L₂] of monodentate ligands with L = 2-isopropylimidazole (L1), 2-methylbenzimidazole (L2), and 2-methylbenzoxazole (L3) and evaluated their antibacterial, antioxidant and DNA binding activities. The chelation-free properties of these coordination complexes were confirmed by UV-visible spectroscopy, ¹H NMR spectroscopy, single X-ray crystallography and elemental analysis. Complexes 1-3 exhibited substantial antibacterial activity against all antibiotic susceptible bacteria within a concentration range of 100-200 µg/ml while free ligands L1 and L2 exhibited weak antibacterial activity considerably concentration above 200 µg/ml. Also, both complexes 2 and 3 were twice more active against methicillin-resistant Staphylococcus aureus (MRSA) than complex 1. Furthermore, we found that complexes 1-3 showed DNA binding activity with E. coli plasmid DNA and calf thymus DNA, which may be a plausible mechanism for their antibacterial activity. We also investigated the antioxidant activity of complexes 1-3 and found that complex 2 exhibited potential antioxidant activity compared to complexes 1 and 3. All these results suggest that the chelation-free Zn(II)-complexes can be the future candidates for more advance biological studies.

中文翻译：

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新型无螯合Zn（II）-唑配合物的合成和表征：抗菌，抗氧化剂和DNA结合活性的评估

在这里，我们合成了新颖的螯合不含Zn（II）-complexes（1 - 3）的ZnCl ₂大号₂单齿配体与L = 2异丙基咪唑（的] L1），2-甲基苯并咪唑（L2），和2-甲基苯并恶唑（L3），并评估它们的抗菌，抗氧化剂和DNA结合活性。这些配位配合物的无螯合性质通过紫外可见光谱，¹ H NMR光谱，单X射线晶体学和元素分析得到证实。配合1 - 3在100-200 µg / ml的浓度范围内，对所有抗生素敏感细菌均显示出显着的抗菌活性，而游离配体L1和L2在200 µg / ml以上的浓度下均显示出较弱的抗菌活性。此外，两种复合2和3对耐甲氧西林的两倍更活性的金黄色葡萄球菌（MRSA ）不是复杂1。此外，我们发现，复合物1 - 3显示DNA结合活性与大肠杆菌质粒DNA和小牛胸腺DNA，这可能是其抗菌活性的合理机制。我们还调查复合物的抗氧化活性1 - 3后发现，复杂的2表现出潜在的抗氧化活性比复合物1和3。所有这些结果表明，无螯合的Zn（II）络合物可以成为更高级生物学研究的未来候选者。