Transition metal complexes derived fromN′‐(4‐fluorobenzylidene)‐2‐(quinolin‐2‐yloxy) acetohydrazide: Synthesis, structural characterization, and biocidal evaluation

Abstract

Mononuclear Mn2+and Cu2+, ‐ VO2+, Co2+, Ni2+, ‐ and Zn2+complexes of a synthetic novel hydrazone containing a quinoline moiety were prepared. The composition and structure of the prepared compounds were elucidated by spectral and analytical techniques. The results reveal that all complexes were formed in 1:1 mole ratio except Mn2+and Cu2+complexes (3) and (7), which were formed in 1 M:2 L mole ratio. It was also found that the ligand binds the metal ions via NO donor sites as a monobasic bidentate chelator in all complexes through the enolic carbonyl oxygen and azomethine nitrogen atoms. The electronic absorption spectra and magnetic moment data demonstrated square pyramidal and octahedral geometries for the VO2+and Ni2+complexes, respectively, while the other complexes adopted tetrahedral geometry. The thermal decomposition of the complexes was discussed in relation to structure. The thermal analysis data demonstrated that all complexes were decomposed in one, two, three or four stages starting with the dehydration process, removal of coordination water molecules or elimination of anions and ended with the formation of the metal oxide. The bactericidal activities of the prepared compounds demonstrated that hydrazone (1)exerted a highly inhibitory effect againstB. subtiliswhile VO2+, Co2+, and Cu2+complexes (2), (4), and (7)showed an inhibitory effect againstE. colimore than the tetracycline. Additionally, the inhibitory effect of the prepared compound againstA. nigershowed that the Cu2+complex (6)is the most active while the Ni2+, Cu2+, and Zn2+complexes (5–8)exhibited an extremely inhibitory effect againstC. albicans.