Tetrabutylphosphonium‐Based Amino Acid Ionic Liquids: Synthesis, Properties, Catalytic Activity, in Silico Analysis, and Study of Biological Activity

Abstract Ionic liquids (ILs) have been proposed as alternatives to organic solvents in recent years because of their environmentally benign nature. Phosphonium cation‐based ILs have engrossed immense interest because of distinctive chemical and thermal stability among different classes of ILs. A simple acid‐base neutralization procedure was used to synthesize and characterize seven ILs containing tetrabutylphosphonium cation and different amino acids as anions. The main objective of the work was to study anion variation effect on the physical properties of ILs (density and viscosity) at different temperatures (298.15–318.15 K). From experimental density data, various physical parameters (molar volume, lattice potential energies, entropies, and thermal expansion coefficient) have been calculated. Minimum inhibitory concentrations were subsequently determined from the toxicity profiles using selected gram‐positive and gram‐negative bacteria. The results showed a relation between antimicrobial activities of ILs and their structures. The work also demonstrates catalytic activity of these ILs in the Knoevenagel condensation reaction without solvent, giving product yields of 41%–92%. High yield, easy procedure, fast reaction time, reusability of catalyst, and solvent‐free condition are some of the benefits of this procedure. Furthermore, the theoretical assessment of ADME properties was examined to predict the effectiveness and safety of the compounds.