FerrocenyI Schiff Bases and their Organic Analogues: Candidates for Technological and Biological Applications

Abstract

Ferrocene containing Schiff bases and their organic analogues with aromatic rings were synthesized by condensation of corresponding amine and dialdehydes. The synthesized compounds were characterized using FT-IR, NMR (1H and 13C) spectroscopic techniques, which confirmed the presence of all the expected moieties in their structures. Potential as well as the biological applications of Schiff bases were studied. In potential application the anticorrosion properties of the Schiff bases for aluminium alloy 2219/T6 in acidic medium were studied and analyzed through weight loss measurement, potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) technique. Moreover, quantum chemical calculations were performed using density functional theory (DFT) to investigate the anticorrosion mechanism and its correlation with electronic and structural properties of the anticorrosive inhibitors. Aluminium alloy surface morphology after corrosion experiments was inspected by FT-IR spectroscopy and scanning electron microscopic (SEM) techniques. The anticorrosion inhibition efficiency for Schiff bases are found to be between 70-98 %. The alkoxy substituted Schiff bases showed better corrosion inhibition efficiency than unsubstituted for all the three series. In comparison the Schiff bases containing ferrocene moiety showed better inhibition efficiency. This is due to protonation of Fe of ferrocene moiety, which contributes in electrostatic attraction between metal substrate and Schiff bases. DNA binding potential of Schiff bases were investigated by UV-visible absorption titrations. It was demonstrated that several compounds showed DNA binding affinities with different magnitude. The binding strengths are calculated from the absorption data and results are interpreted in the form of intrinsic binding constant (Kb) values which are found to be in the range of 6.4×103 -1.09×104M ‒1 . The compounds of all the series exhibited mixed mode of binding i.e, intercalative and groove binding. Owing to negative free energy values (-ΔG°) the binding forces are thermodynamically spontaneous. Moreover, antioxidant activities, enzyme inhibition assays were applied to evaluate the antioxidant behavior and antidiabetic behavior of Schiff bases. Antitumor potato disc assays were applied to further evaluate their antitumor activities. Finally, the cytotoxic properties of the synthesized compounds were explored via brine shrimp cytotoxic assay. Most of the compounds were found non-toxic with LD50 value >200μg/ml.