Two novel Cu (II) levofloxacin complexes with different bioactive nitrogen‐based ligands; single‐crystal X‐ray and various biological activities determinations

Abstract

AbstractTwo new copper (II) complexes with the third generation quinolone antibacterial agent levofloxacin, 2‐aminopyridine and 2,2′‐bipyridine nitrogen‐based ligands with the following molecular structures [Cu (levo)2(2‐ampy)].6.25H2O (1) and [Cu (levo)(H2O)(2,2‐bipy)](NO3).2.5H2O (2) were synthesized. The complexes were characterized by spectroscopic methods and others. The crystal structure of complex 1 revealed that the Cu (II) cation is coordinated to two bidentate chelating levofloxacinato ligands, and one monodentate 2‐ampy ligand in the axial position forming a slightly distorted square pyramidal geometry. The mononuclear cationic complex 2 was determined in the triclinic crystal system and the chiral space group P1 with four molecules per unit cell in which the Cu (II) cation is coordinated to one bidentate chelating levofloxacinato ligand, one bidentate 2,2‐bipy, and one water molecule in a distorted square pyramidal geometry. In vitro antibacterial activities for the complexes and their parent ligands against four gram‐negative bacteria (Proteus mirabilis, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia) and four gram‐positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, and Enterococcus faecalis) using the agar diffusion method have been determined with inhibition zone diameter (IZD) values between 29 and 46 mm. In addition, the minimum inhibition concentration (MIC) and the minimum bactericidal concentration (MBC) have been investigated. The MIC results of complexes 1 and 2 showed significant antibacterial activities against the P. mirabilis and B. subtilis than levofloxacin.