Cu (II), Ni (II), Co (II), and Mn (II) acetato in addition to Cu (II) chloro and nitrato mixed ligand complexes of 4-([quinolin-2-yl]methyleneamino)-1,-2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one (L), as a primary ligand and 2,4-dihydroxy benzaldehyde (H 2 L), as a secondary ligand have been isolated. The structural features and geometrical arrangements of the synthesized mixed ligand complexes were identified by elemental analysis, Fourier transform infrared spectroscopy (FT-IR), conductivity measurements, UV-Vis spectra, magnetic moment measurements, X-ray diffraction, and electron spin resonance (ESR) spectral and thermogravimetric techniques studies of the mixed ligand complexes confirming the molar ratio 1:1:1 (primary ligand: M: secondary ligand) for Cu (II), Co (II), Mn (II), and UO 2 (II) chelates. The spectral techniques also confirmed the metal chelates have the formulae (Cu[H 2 L][L][X] 2 ), where X = Cl À (1); NO 3 À (2); and (M[L][HL][OAc])YH 2 O, where M = Cu (II) (3), Co (II) (4); Y = 1, Mn (II) (5); Y = 1 and UO 2 (II) (6); Y = 2. The kinetic and thermodynamics parameters of the mixed ligand complexes at different decomposition steps were calculated using Coast-Redfern and Horowiz-Metzger methods. Also, the antimicrobial activities of ligands and their mixed ligand complexes were screened by Disc Diffusion method. It was found that all mixed ligand complexes (1-6) have high antibacterial activity against Klebsiella pneumoniae than penicillin G. By studying the molecular docking between the quinoline-2-carbaldehyde, the ligand and the receptors (Escherichia coli (PDB code: 3t88), Staphylococcus aureus (PDB code: 3q8u),lung cancer (PDB code: 1x2j), and colon cancer (PDB code: 2hq6)), it was found that the ligand is efficient compound for all the receptors than the quinoline-2-carbaldehyde. The DNA cleavage properties of the two ligands and their complexes have been investigated by gel electrophoresis and the results showed that complex (1) without H 2 O 2 and complex (6) with H 2 O 2 exhibited a significant partial oxidative cleavage among other complexes.
