Synthesis, characterization, antimicrobial activity and in silico study of pyridinium based ionic liquids

Abstract

A series of twenty-one pyridinium-based ionic liquids (ILs) was synthesized and thoroughly characterized using FTIR, NMR, UV-Vis spectroscopy, and melting point analysis. The ILs' antibacterial activity was assessed against Aspergillus niger and a panel of bacteria, both Gram-positive and Gram-negative. Notable antibacterial and antifungal properties were demonstrated by IL-10, IL-11, and IL-14 specifically. Several ILs also demonstrated effective Brønsted acidic catalysis for the Mannich process under mild, solvent-free circumstances. The biological activity of IL-19 and IL-21 was found to be correlated with their significant binding affinities to microbial protein targets, as demonstrated by molecular docking experiments. Selected ILs, especially IL-05 and IL-21, were found to be drug-like and biosafe based on ADMET and toxicity predictions. These results highlight the pyridinium-based ILs' multipurpose potential as green catalysts and antibacterial agents for sustainable synthetic applications.

Fig. 1. Commonly used cations and anions in ionic liquids.

Fig. 2. Some pyridinium containing ILs, With their low volatility and potential for recycling, ionic liquids present promising opportunities for greener synthesis routes and cleaner processes, aligning with the growing imperative for eco-friendly practices in both academic research and industrial applications.

Scheme 1. Synthesis of pyridinium carboxylate ionic liquids.

Fig. 3. Six human pathogens Gram positive and Gram negative which were killed by different types of pyridinium based ionic liquids.

Fig. 4. Boiled egg representation of ILs.

Fig. 5. Bioavailability radar of ILs.