One-Pot Green Synthesis of Cyclohepta[d]pyrimidine-2(5H)-thione Derivatives using Iron Titanate (FeTiO3, Ilmenite) Nanoparticles and Evaluation of their Antibacterial Activity

Abstract

Iron titanate nanoparticles (FeTiO₃-NPs, TiFe-0.5, TiFe-1.0, TiFe-2.0 with fixed and variable compositions of Fe and Ti, respectively) were synthesized under ultrasonication and characterized using XRD, FESEM-EDAX and UV-vis DRS spectral techniques. The XRD analysis has clearly indicated the characteristic peaks in the nanoparticles. The morphologies have shown the spherical shaped particles and in the EDAX analysis, the respective elements (Fe, Ti, O) in the prepared nanoparticles were identified. Similarly, the absorption maxima of the nanoparticles have increased with increase in the Ti content between 380-570 nm. Using these nanoparticles, cyclohepta[d]pyrimidine-2(5H)-thione derivatives (4a-e) were synthesized through one-pot approach with cycloheptanone (1), some substituted benzaldehyes (2a-e) and thiourea (3) as the precursors, which was performed under the guidelines of green chemistry. The progress of the reactions were monitored by TLC and the formed derivatives were characterized by using ¹H NMR, FTIR and Mass spectral techniques along with the determination of their melting points. The NPs were magnetically separable and with its recycled forms, the reaction was conducted in 3 consecutive cycles and observed that the % yields have not varied much. The antibacterial activity studies were conducted against Gram-negative Escherichia coli, Klebsiella pneumonia, Gram-positive Staphylococcus aurues, Bacillus subtilis bacteria with the derivatives (4a-e). In these studies, almost all the derivatives have shown from moderate to better antibacterial activity.