Synthesis, spectral characterisation, DFT calculations, biological evaluation and molecular docking analysis of new Mannich compounds derived from cyclopentanone

This research outlines the efficient one-pot calcium chloride-catalysed synthesis of three novel Mannich bases: M1, M2 and M3. M1 and M2 resulted from the condensing of benzaldehyde with m-nitroaniline and m-bromoaniline, respectively, in conjunction with cyclopentanone. However, M3 was obtained through the reaction of p-methoxybenzaldehyde, m-bromoaniline and cyclopentanone. The isolated compounds were thoroughly characterised using elemental analysis and various analytical and spectroscopic techniques, including the determination of their melting points, electrospray mass spectrometry (ESMS), Fourier transform infrared (FTIR), electronic spectroscopy (UV-Vis), and nuclear magnetic resonance (NMR) spectroscopy (1H- and 13C NMR). Thermal stability (TGA and DTA analysis) of the three Mannich compounds was also examined. The newly synthesised Mannich bases exhibit remarkable potential as metal ion complexing agents and as fundamental building blocks for forming small organic molecules, particularly bioactive molecules and novel ligands for coordination chemistry. In addition to their structural significance, the biological efficacy of these compounds was assessed, revealing their excellent antimicrobial properties toward bacterial and fungal species. These activities suggest their potential use in combating microbial infections. Theoretical DFT simulations employing the B3LYP functional at the 6-311++G(d,p) level provided a thorough analysis of the stability of compounds, electrical properties, and geometry. Additionally, molecular docking studies of the Mannich compounds with two protein targets, 5IQ9 and 5VBU (both relevant for drug discovery) were performed. These studies revealed that the three Mannich compounds exhibit similar binding energies and effective interaction with both the 5IQ9 and 5VBU proteins, suggesting the potential of these Mannich compounds as dual inhibitors targeting both proteins.