A novel tridentate Schiff base, 1-((E)-(2-mercaptophenylimino) methyl) naphthalen-2-ol (H2L1), was synthesized by the condensation reaction of 2-hydroxy-1-naphthaldehyde with 2-aminothiophenol in absolute ethanol. The resulting ligand was reacted with Co(II), Ni(II), and Cu(II) ions to obtain tetrahedral CoL1, NiL1, and square planar CuL1 complexes. The Schiff base and its metal complexes were characterized using 1H-NMR, microanalysis, FT-IR, UV-visible, and mass spectroscopy (ESI-MS). All the compounds are soluble in DMSO and DMF. Spectroscopic studies show that the ligand coordinates to the metal center through the azomethine nitrogen, naphthoxide oxygen, and thiophenoxide sulfur to form a tridentate chelate system. Conductance measurements show that these compounds are molecular in solution. Cyclic voltammetry studies show Co(III)/Co(II) and Cu(II)/Cu(I) redox systems to be quasi-reversible involving a monoelectronic transfer while Ni(III)/Ni(II) was irreversible. In vitro antibacterial and antifungal activity against five bacterial strains (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis, and Proteus mirabilis) and five fungal strains (Candida albicans, Candida glabrata, Candida tropicalis, Candida krusei, and Candida parapsilosis) showed no antifungal activity but moderate antibacterial activity on E. coli, S. aureus, P. aeruginosa, and P. mirabilis bacterial strains. Antioxidant studies reveal that the ligand and its Cu(II) complex are more potent than Co(II) and Ni(II) complexes to eliminate free radicals.

中文翻译：

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三齿席夫碱 1-((E)-(2-Mercaptophenylimino) Methyl) Naphthalen-2 的 Co(II)、Ni(II) 和 Cu(II) 配合物的合成、表征、循环伏安法和生物学研究-ol (H2L1)

通过2-羟基-1-萘醛与2-氨基苯硫酚在无水乙醇中的缩合反应合成了一种新型三齿席夫碱1-((E)-(2-mercaptophenylimino)methyl)naphthalen-2-ol (H2L1) . 所得配体与 Co(II)、Ni(II) 和 Cu(II) 离子反应，得到四面体 CoL1、NiL1 和方形平面 CuL1 配合物。席夫碱及其金属配合物使用 1H-NMR、微量分析、FT-IR、UV-可见光和质谱 (ESI-MS) 进行表征。所有化合物均溶于 DMSO 和 DMF。光谱研究表明，配体通过偶氮甲碱氮、萘氧基氧和噻吩氧硫与金属中心配位，形成三齿螯合系统。电导测量表明这些化合物在溶液中是分子的。循环伏安法研究表明 Co(III)/Co(II) 和 Cu(II)/Cu(I) 氧化还原系统是准可逆的，涉及单电子转移，而 Ni(III)/Ni(II) 是不可逆的。对五种细菌菌株（大肠杆菌、金黄色葡萄球菌、铜绿假单胞菌、粪肠球菌和奇异变形杆菌）和五种真菌菌株（白色念珠菌、光滑念珠菌、热带念珠菌、克柔念珠菌和无假丝酵母菌）的体外抗菌和抗真菌活性具有抗真菌活性，但对大肠杆菌、金黄色葡萄球菌、铜绿假单胞菌和奇异假单胞菌细菌菌株具有中等抗菌活性。抗氧化研究表明，配体及其 Cu(II) 配合物比 Co(II) 和 Ni(II) 配合物更有效地消除自由基。