Synthesis, characterization, biological activity, and corrosion inhibition in acid medium of unsymmetrical tetradentate N 2 O 2 Schiff base complexes

Four divalent metal(II) complexes, namely [Co(II)L(H 2 O)Cl]·2H 2 O, [Ni(II)L(H 2 O)Cl]·4H 2 O, [Cu(II)L(H 2 O)Cl]·3H 2 O, and [Zn(II)L(H 2 O)Cl]·5H 2 O, {L = 2‐furan‐2‐ylmethyleneamino‐phenyl‐iminomethylphenol}, were synthesized and characterized by several techniques. The molar conductance measurement of all analyzed complexes in DMSO showed their non‐electrolytic nature. The new Schiff base ligand (HL) acts as tetradentate ligand, coordinated through deprotonated phenolic oxygen, furan ring oxygen, and two azomethine nitrogen atoms. The ligand field parameters were measured for the metal complexes, which were found to be in the range notified for an octahedral structure. The molecular structural parameters of the synthesized HL ligand and its related metal(II) complexes were calculated and correlated with the experimental parameters such as infrared (IR) data. The investigated ligand and metal complexes were screened for their in vitro antimicrobial activities against different types of fungal and bacterial strains. The resulting data confirmed the examined compounds as a highly promising bactericides and fungicides. The antitumor activities of all inspected compounds were evaluated against colon carcinoma (HCT‐116) and mouse myelogenous leukemia carcinoma (M‐NFS‐60) cell lines. The inhibition effect of HL ligand and its isolated complexes on the corrosion carbon in the form of a rod of area 0.35 cm 2 in HCl was investigated by measuring the weight loss at 25 °C.