Crystal structures of three transition metal complexes with salicylaldehyde-4-hydroxy phenylacetyl acylhydrazone and their interactions with CT-DNA and BSA

A novel salicylaldehyde-4-hydoxy phenylacetyl acylhydrazone (C15H14N2O3, HL) and its three new mononuclear complexes, [CuLPy]NO3 (1), [CuLCl(EtOH)] (2) and [CoL2]NO3·EtOH (3), were synthesized. The interactions of the four compounds with DNA/BSA have been studied by UV–Vis spectroscopy, fluorescence spectroscopy, microcalorimetry and molecular docking methods. Furthermore, the antibacterial activities of the four compounds were determined. [Display omitted] A salicylaldehyde-4-hydroxy phenyl acetyl acyl hydrazone (C15H14N2O3, HL) and its three complexes ([CuLPy]NO3 (1), [CuLCl(EtOH)] (2) and [CoL2]NO3·EtOH, (3)) were synthesized. The single crystal X-ray diffraction results of 1, 2 and 3 showed that the coordination atoms (N and O atoms) in the complexes exhibited four-coordinated pyramidal, five-coordinated and six-coordinated octahedral geometries centered on the metal ions, respectively. TG-DTG techniques illustrated that the maximum thermal decomposition peak temperatures of these compounds were all higher than 200 ℃, exhibiting strong thermal stabilities. All four compounds, HL, 1, 2 and 3, quenched the intrinsic fluorescence of BSA by means of static processes, as investigated by fluorescence spectra, which suggested that these compounds could effectively combine with BSA to form non-fluorescent ground state complexes. The UV–vis spectra showed that HL, 1, 2 and 3 effectively combined with CT-DNA through intercalative modes. Microcalorimetry tests indicated that the interaction processes of HL, 1 and 2 with BSA and CT-DNA were all spontaneously exothermic and entropy reducing, and each of the interaction durations was within 50 min. The interactions of the four compounds with BSA and CTDNA were also simulated by the molecular docking method, showing that the four compounds had hydrogen bonds and hydrophobic interactions with BSA and CT-DNA. The antibacterial activities of HL, 1, 2 and 3 against S. aureus, P. aeruginosa, B. subtilis and E. coli were determined, revealing that 1 and 2 exhibit stronger inhibition activities against P. aeruginosa than gentamicin sulfate. Complexes 1 and 2 are potential alternative drugs to gentamicin sulfate in the future.