This paper reports the synthesis and detailed characterisation of copper(II) and nickel(II) complexes with tridentate thiosemicarbazone ligands H₂L1 and H₂L2 derived from 2-acetylpyrazine. The ligands and their metal complexes were characterised by different physicochemical techniques, including elemental and thermogravimetric analysis; UV-Vis, IR, ¹H-NMR, and ¹³C-NMR spectroscopy; molar conductance measurements; and mass spectrometry. The crystal structure of the H₂L1 ligand was determined by single crystal X-ray diffraction studies. The spectral data showed that the thiosemicarbazone behaves as an NNS tridentate ligand through the nitrogen atoms of the azomethine group and pyrazine ring and the sulphur atom of the thioamide group. Elemental and thermal analyses indicated that the obtained metal complexes had a 1 : 1 stoichiometry (metal-ligand). The interactions between these complexes and calf thymus DNA (CT-DNA) were studied by electronic absorption and viscosity measurements. The activities of these compounds against oxidative DNA cleavage were examined by agarose gel electrophoresis. Cu(II) and Ni(II) complexes can wind DNA strands through groove interactions and promote strand breakage of the plasmid pmCherry under oxidative stress conditions. Moreover, all the complexes could interact more strongly with DNA than could with the free ligands. Finally, the antibacterial activities of the ligands and their complexes were determined by in vitro tests against Gram-positive bacterial strains (S. aureus ATCC 25923, L. monocytogenes ATCC 19115, and B. cereus ATCC 10876) and Gram-negative bacterial strains (E. coli ATCC 25922, S. typhimurium ATCC 14028, and K. pneumoniae ATCC BAA-2146) using the broth microdilution method. The metal complexes showed greater antimicrobial activities than the precursor ligands against some of the microorganisms.

中文翻译：

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Cu(II) 和 Ni(II) 与新型三齿 NNS 缩氨基硫脲的配合物：合成、表征、DNA 相互作用和抗菌活性。


本文报道了由2-乙酰吡嗪衍生的三齿缩氨基硫脲配体H ₂ L1和H ₂ L2铜(II) 和镍(II) 配合物的合成和详细表征。通过不同的物理化学技术，包括元素分析和热重分析，对配体及其金属配合物进行了表征； UV-Vis、IR、 ¹ H-NMR 和¹³ C-NMR 光谱；摩尔电导测量；和质谱分析。 H ₂ L1配体的晶体结构通过单晶X射线衍射研究确定。光谱数据表明，缩氨基硫脲通过甲亚胺基团和吡嗪环的氮原子以及硫代酰胺基团的硫原子充当NNS三齿配体。元素和热分析表明所获得的金属配合物具有1:1的化学计量（金属-配体）。通过电子吸收和粘度测量研究了这些复合物与小牛胸腺 DNA (CT-DNA) 之间的相互作用。通过琼脂糖凝胶电泳检测这些化合物抗氧化 DNA 裂解的活性。 Cu(II) 和 Ni(II) 复合物可以通过凹槽相互作用缠绕 DNA 链，并在氧化应激条件下促进质粒 pmCherry 的链断裂。此外，所有复合物与 DNA 的相互作用都比与游离配体的相互作用更强。最后，通过针对革兰氏阳性菌株（ S. aureus ATCC 25923、 L. 使用肉汤微量稀释法检测单核细胞增生李斯特菌 ATCC 19115 和蜡样芽孢杆菌ATCC 10876）和革兰氏阴性细菌菌株（大肠杆菌ATCC 25922、鼠伤寒沙门氏菌ATCC 14028 和肺炎克雷伯菌ATCC BAA-2146）。金属配合物对某些微生物表现出比前体配体更强的抗菌活性。