Synthesis and Characterization of (E)-2-((Benzo[b]thiophen-3-yl)methyleneamino)butanoic Acid and Its Metal Complexes

This study describes the techniques used for the synthesis and characterization of mononuclear, heterocyclic ligated complexes of Zn(II), Mn(II), and Sn(II). A heterocyclic Schiff base derivative, specifically (E)-2-((benzo[b]thiophen-3-yl)methyleneamino)butanoic acid, has been synthesized by the reaction of benzo[b]thiophene-3-carbaldehyde with 2-aminobutanoic acid. This Schiff base has been reacted with different (M)Cl2 to synthesize the respective metal complexes. For these metal ions, Schiff bases have been proven experimentally to form four-coordinate complexes with 1 : 2 (metal : ligand) ratio. The structural changes of the complexes have been investigated using FT-IR, mass, 1H NMR, 13C NMR spectra, and TGA analysis. The antibacterial efficacy of the Schiff base and its complexes has further been assessed and discussed. Significant amounts of antibacterial and antifungal activity of metal(II) complexes against tetracycline and ketoconazole have been identified.