Synthesis, crystal structures, catalytic application and antibacterial activities of Cu(II) and Zn(II) complexes bearing salicylaldehyde-imine ligands

Abstract Three novel copper(II) and zinc(II) complexes based on salicylaldehyde-imine ligands, namely [Cu(HL1)(CH3CH2OH)]·(CH3COO) (1), [Zn3(HL1)2(CH3COO)4] (2), and [Zn2(L2)]·(CH3COO) (3) [H2L1 = N,N’-bis(salicylidene)diethylenetriamine and H3L2 = 2,2'-(1E,1'E)-(2,2'-(2-(2-hydroxyphenyl)imidazolidine- 1,3-diyl)bis(ethane-2,1-diyl))bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)diphenol] have been synthesized. The complexes were characterized by IR, melting point, and elemental analyses, and the crystal structures were further determined by single crystal X-ray diffraction. These three complexes demonstrated excellent catalytic activities in the decomposition reaction of H2O2, and the decomposition percent of the H2O2 ranged from 89% to 98% under the optimized reaction conditions. Additionally, the compounds were screened as antibacterial agents against three gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) and three gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus and Corynebacterium xerosis). The results showed that complex 2 possessed stronger antibacterial activities than the two ligands and other two complexes.