Synthesis, characterization and antimicrobial evaluation of copper(II) complexes of 5-tert-butyl-pyrocatechin-derived Mannich bases

Cu(II) complexes with 5-tert-butyl-3-(pyrrolidine-1-ilmethyl)-1,2-dihydroxybenzene (I), 5-tert-butyl-3-(piperidine-1-ilmethyl)-1,2-dihydroxybenzene (II), 5-tert-butyl-3-(azenone-1-ilmethyl)-1,2-dihydroxybenzene (II), 5-tert-butyl-3-(morpholine-1-ilmethyl)-1,2-dihydroxybenzene (IV), and 5-tert-butyl-3-(methylpiperazine-1-ilmethyl)-1,2-dihydroxybenzene (V) have been synthesized and characterized by means of elemental analysis, TG/DTA, FT-IR, ESR, UV-Vis spectroscopy and conductivity measurements. According to the data obtained, the compounds I-V coordinate in their singly deprotonated forms in an O,N-bidentate fashion. The synthesized complexes have the composition described by the general formula CuL2 and are characterized by square planar geometry of their coordination cores CuO2N2. The Cu(II) complexes have been screened for their antimicrobial activity on different species of pathogenic bacteria, fungi, and their antimicrobial potency has been discussed. A high antibacterial activity against Mycobacterium smegmatis and Pseudomonas aeruginosa has been found for the Cu(II) complexes synthesized.