Impact of functional group positioning in the anion of ionic liquids on aqueous solubility: a study through DFT calculations

Noscapine is one of the leading antitussive drugs available but it also faces the huge task of solubility. Ionic liquids are found to have high water solubility and stability. The authors have designed ionic liquids of noscapine and studied their interactions using DFT calculations. It was found that both the solubility and stability of noscapine increase with its ionic liquids. On changing the temperature from 298 to 310 K and the solvent system from default to water there is a significant change in the dipole moment, free energy, and optimization energy. One of its derivatives nocapinium benzoate has a dipole moment of 20.36 at 310 K in water. Along with this DFT-IR spectra data for noscapine and its ionic liquids was also obtained. The decrease in the difference between energies of HOMO and LUMO indicate that these ionic liquids have more antioxidant character than noscapine alone.