Three new dinuclear nickel(II) complexes with amine pendant-armed ligands: Characterization, DFT study, antibacterial and hydrolase-like activity

Abstract

Herein, we report the synthesis and characterization of three new Ni(II) complexes, namely: [Ni2(H2LEt)(μ-OAc)2(H2O)]BPh4‧ClO4 (1), (H2LEt = 2-[(N-benzyl-N-2-pyridyl methylamine)]-4-methyl-6-[N-2(pyridylmethyl)aminomethyl)]-6((2-aminoethyl)amino)methyl phenol); [Ni2(H2LProp)(μ-OAc)2(H2O)](ClO4)2 (2), (H2LProp = 2-[(N-benzyl-N-2-pyridylmethylamine)]-4-methyl-6-[N-(2-pyridylmethyl)aminomethyl]-6-((2-aminopropyl) amino)methylphenol); and [Ni2(LBut)(μ-OAc)2(H2O)](HCl)2 (3), (LBut = 2-[(N-benzyl-N-2-pyridylmethylamine)]-4-methyl-6-[N-(2-pyridylmethyl)aminomethyl]-6-((2-aminobuthyl) amino)methylphenol). All of them were characterized through spectroscopic techniques (elemental analysis, IR, UV–Vis spectroscopy), ESI-MS, electrochemistry and potentiometric titration. Density functional theory (DFT) was used to better understand the electronic and molecular structure of these complexes. The hydrolytic activity of complexes 1–3 towards the 2,4-BDNPP substrate was analyzed and complex 2 presented the highest catalytic efficiency (kcat/KM) of the three, possibly due to a greater interaction with the substrate. The complexes were also screened for their antibacterial activities using both Gram-positive and Gram-negative bacterial strains by minimum inhibitory concentration and minimum bactericidal concentration methods.