Synthesis, characterization, antimicrobial activity and computational exploration of ortho toludinium carboxylate ionic liquids

Abstract

As Ionic Liquids (IL) was considered as designer molecules for use in chemical and biological sectors, its demands and researches have been increasing day by day. To design new ILs and evaluate its antimicrobial activities, the ortho-toludinium carboxylate ionic liquids (OTILs) were synthesized through the Brønsted acid-base neutralization reaction between ortho toluidine and carboxylic acids with yields (74 to 88)%. The synthesized OTILs were characterized by FT-IR, UV and 1H-NMR, which had confirmed their conversion of the reaction and their structure. The eight human pathogenic bacteria were used for antibacterial screening, as well as three antifungal activities had estimated against three fungi. However, the synthesized ILs showed the good result to antimicrobial activity against both bacteria and fungi. Due to show high antimicrobial activity, MIC was performed against two bacteria whereas the MIC had found the range 250 to 500 mM. Furthermore, density functional theory (DFT) had used for determining the HOMO, LUMO and chemical reactivity descriptors for the computational investigation of OTILs, as well as molecular docking screening had performed against three pathogens. By the molecular docking score as binding affinity and chemical descriptors, the effect of alkyl chain and electronegative atom in anion had direct contribution on antimicrobial activity which was the similar result from the experimental data of antimicrobial activity. Finally, attaching Fluorine atom in anion could show the highest antimicrobial activity and docking score among chlorine, bromine, iodine even alkyl chain.