Easily attainable new approach to mass yield ferrocenyl Schiff base and different metal complexes of ferrocenyl Schiff base through convenient ultrasonication-solvothermal method

A new alternative approach with crucial mass yield and high reaction rates is proposed for the synthesis of ferrocenyl Schiff bases using an ultrasonication-solvothermal method. Equimolar condensation of ferrocenecarboxaldehyde and 2-aminophenol interact with each other, giving 1-(1-[2-hydroxyphenyl-2-imino]methyl)-ferrocene (FcOH). Furthermore, this ligand forms 1:1 complexes with cobalt(II), nickel(II), copper(II), and palladium(II) ions. From the different spectral data, it is found that metal ions coordinate with ligands through the azomethine group and the deprotonated oxygen of the phenol groups. Moreover, FcOH and their complexes were characterized by elemental analysis, Fourier transform infrared, ¹H nuclear magnetic resonance, and UV-visible spectrophotometry. The spectral data of FcOH and its metal complexes were discussed in connection with the structural changes due to complexation. Meanwhile, the information about geometric structures can be concluded from the electronic spectra and the magnetic moments. Plainly, electron spin resonance spectra of the Cu(II) complex revealed d_x2−y2 as a ground state, suggesting a square planar geometry around the Cu(II) center. The direct optical band gap energy E_g values of cobalt, nickel, copper, and palladium complexes of FcOH are found to be 3.7, 3.9, 4.6, and 3.65 eV, respectively. 1-(1-[2-Hydroxyphenyl-2-imino]methyl)-ferrocene and its metal complexes were screened for antibacterial activity. The results depict that the metal complexes were found to be more strongly antibacterial than the guardian Schiff base ligand (FcOH) against one or more bacterial species. The minimum inhibitory concentrations of antimicrobial properties of the purified compound were determined using the broth microdilution method.