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

Three novel copper(II) and zinc(II) complexes based on salicylaldehyde-imine ligands, namely [Cu(HL1) (CH3CH2OH)]center dot(CH3COO) (1), [Zn-3(HL1)(2)(CH3COO)(4)] (2), and [Zn-2(L2)]center dot(CH3COO) (3) [H(2)L1 = N,N'-bis(salicylidene)diethylenetriamine and H(3)L2 = 2,2'-(1E,1'E) (2,2' (2 (2 hydroxyphenyeimidazolidine-1,3-diyebis (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 Cotynebacterium xerosis). The results showed that complex 2 possessed stronger antibacterial activities than the two ligands and other two complexes.