Synthesis of bioactive ionic liquids through the reaction between aryl amine and carboxylic acids

Abstract

Ionic Liquids are recognized as the safer, greener, designer, and engineering chemical for 21st century. As 3rd generation ILs was established as pharmaceutical active ingredients and bioactive molecules, it consists of synthesis, characterization, and computational approaches for synthesis of bioactive ILs. Total twenty five quaternary aryl ammonium ILs were synthesized combination of five different cations like aniline, o-toluidine, m-toluidine, p-toluidine, and 1,2-diaminebenzene and five aliphatic carboxylic acids like formic acid, acetic acid, propanoic acid, butanoic acid and trifluroacetic acid by the Bronsted acid-base neutralization reaction. For confirmation the structure, Fourier Transform Infrared (FT-IR), and Nuclear Magnetic Resonance (1H-NMR) and UV spectroscopy were used. The melting points were found in about 62-86ºC and some have more than 150º C. To evaluate antimicrobial profiles against eight human pathogenic bacteria, three phytopathogenic fungi were used via well diffusion method and all ILs show the positive result. The minimum inhibition concentration (MIC) was found from 500 mMol/L to 125 mMol/L. Morever, biological studies against plant seed, the phytotoxicity was done using concentrations of 1000mmol/L, 500mmol/L, 250 mmol/L, 0 mmol/L, respectively and obtained the positive result. Finally, the computational tools were used to evaluate the theoretical investigation of thermo-physical, chemical reactivity and biological interaction by the method of density functional theory (DFT). From the both of computational and biological studies, the anilinium and 1,2- diammoniumphenyl carboxylate in comparatively lower times than others for synthesis and also chemical and biological activity are higher. The alkyl chain length in anion and functional groups in aromatic ring in cations had experienced the change of chemical, biological study. The longer alkyl chain length shows higher chemical and biological activity while substituent group in various position of cation accounted for closer activity. The bi-cation shows much higher the chemical, physical and biological activity than mono ammonium cation. Additionally, halogen atom attaching in anion illustrates the higher biological activity.