@article{scholars11691,
           pages = {309--319},
             doi = {10.1016/j.molliq.2019.01.048},
           title = {Synthesis, characterisation and antioxidant properties of ferulate-based protic ionic liquids: Experimental and modelling approaches},
          volume = {278},
       publisher = {Elsevier B.V.},
            year = {2019},
         journal = {Journal of Molecular Liquids},
            note = {cited By 13},
            issn = {01677322},
        keywords = {Crystalline materials; Density functional theory; Free radicals; Hydrogen bonds; Ionic liquids; Positive ions; Probability density function; Spectrum analysis, Active pharmaceutical ingredients; COSMO-RS; Density function theory calculations; DFT calculation; Dpph radicals; Free radical scavenging; Intermolecular hydrogen bonds; Protic ionic liquids, Antioxidants},
          author = {Ahmad, N. A. and Jumbri, K. and Ramli, A. and Ghani, N. A. and Ahmad, H. and Kassim, M. A.},
        abstract = {Active pharmaceutical ingredients (APIs) in the form of crystalline solid are commonly produced in drug manufacturing industries. However, crystalline solid APIs have a low solubility and the ability to cause polymorphism transformation. In order to overcome these problems, a modification of APIs in the form of protic ionic liquids (PILs) has been proposed. In the present study, a series of five ferulate-based PILs were successfully synthesised and characterised by appropriate spectral analysis. The antioxidant activity of synthesised PILs was determined through the 2,2{\^a}??diphenyl{\^a}??1{\^a}??picrylhydrazyl (DPPH) free radical scavenging assays. The spectroscopy analysis confirmed the formation of PILs supported by the Density Function Theory (DFT) calculation. The synthesised ferulate-based PILs exhibited low EC 50 ranging from 12.93 {\^A}{$\pm$} 0.05 to 17.40 {\^A}{$\pm$} 0.04 {\^I}1/4M indicating a strong antioxidant activity compared to parent acid (EC 50 of 21.40 {\^A}{$\pm$} 0.05 {\^I}1/4M). Prediction of antioxidant activity of the PILs and their ionic interactions at the molecular level were studied by applying DFT calculation at B3-LYP/6-311G*** level and COSMO-RS. Based on the optimised geometry, the ion-pair of PILs formed a strong directional intermolecular hydrogen bond between the {\^a}??NH group of the cation with the {\^a}??COOH group of the anion with interaction energy of {\^a}??111 to {\^a}??120 kcal mol {\^a}??1 . Predicted antioxidant activity indicated that the PILs's cation has a weak interaction with an anion as observed from the {\"I}?-potential analysis. {\^A}{\copyright} 2019 Elsevier B.V.},
             url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060105123&doi=10.1016\%2fj.molliq.2019.01.048&partnerID=40&md5=622db65f63683cc4be89bfa0367b1d8c}
}