Preparation, thermal analyses and biological activities of Co(II) and Cr(III) complexes with 2-acetylpyridine-6-bromo-2-naphthoyl acylhydrazone

Abstract

Novel six-coordinated octahedral Co(II) complex [C36H26Br2CoN7O5, 1] and Cr(III) complex [C36H26Br2CrN6O2, 2] were prepared by the chelation reaction of the ligand 4-methoxybenzaldehyde-6-bromo-2-naphthoyl acylhydrazone and 2-acetylpyridine with Co(NO3)2·6H2O or CrCl3·6H2O in ethanol, and it is interesting that the coordination organic group wasn't the original acylhydrazone. Based on X-ray single crystal diffraction technique, the structures of 1 and 2 were characterized, which revealed 1 belonged to monoclinic system and P21/n space group, whereas 2 belonged to triclinic system and P1¯ space group. The apparent activation energies of the thermal decomposition of 1 and 2 showed 1 had far better thermal stability than 2. Both of 1 and 2 quenched the intrinsic fluorescence of BSA through static processes, which suggested 1 and 2 could bind to BSA effectively and the non fluorescent ground state complexes were formed. UV–Vis spectra indicated each complex bound to ct-DNA by an intercalative mode. Microcalorimetry experiments illustrated the interactions of two complexes with BSA and ct-DNA were both spontaneous endothermic processes and the binding abilities of 1 with BSA and ct-DNA were greater than that of 2. The minimum inhibitory concentrations (MIC) of each complex against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa were all 50 μg·mL−1.