The redox-activity of novel bioactive Ni(II) complexes with ortho- and meta-diphenols was investigated. Amorphous water insoluble complexes with general formula NiL2 were synthesized according to the authorial method. It was found that the complexes are highly lipophilic (lgP_ow= 2.5÷3.5), stable in water-organic media (stability constants logarithm lgβ=15-18) and have a non-electrolyte nature. Voltammetry analysis was used to determine the first oxidation peak (E_pa¹, V) as a thermodynamic criterion of compounds’ reducing ability. It was found that complexes with ortho-diphenol derivatives possess stronger reducing ability then the complexes with meta-diphenol. Antimicrobial activity of Ni(II) complexes against Mycobacterium smegmatis and Candida albicans were evaluated. Intricate dependence between reducing ability and bactericidal activity was found.

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