Designing of new functionalized imidazolium based ionic liquids attached to the antracene derivatives and investigation on the influence of intramolecular hydrogen bondings in anions on their intermolecular hydrogen bondings and some of the other properties: A DFT M06-2X-GD3 study

Abstract

To promote the development of new functionalized ionic liquids, it is necessary to get a deeper insight into their features of physicochemical and electronic and molecular structure. In this study, the interaction energies and structural and vibrational frequencies parameters in accompanied with some of the physiochemical, electronic and optic attributes of ionic liquids designed by the covalently attachement of imidazolium to anthracene derivatives ([X-AnMIM][A2] and [X-AnMIM][A3], X: NH₂, OH, OMe, H, Cl, CHO, CN and NO₂) ILs have been evaluated. Two conjugate bases of acids 1,3,5-pentanetriol (A2) and 3-(2-hydroxyethyl)-1,3,5-pentanetriol (A3) are used as anions which have two and three intramolecular hydrogen bonds, respectively. Based on the results of calculations at M06-2X-GD3/6–311++(d,p) level of theory, the differences in these properties in addition to the structural type of anions and cations can be attributed to the cation-anion, intra and intermolecular hydrogen bonding, interactions in ionic liquids. The results depict that the ILs based on A2 anions form stronger hydrogen bonds with [X-AnMIM]⁺ cations. The potency of interaction between cations and anion reduces with the increasement in the number of intramolecular hydrogen bonds and also decreasement in the basic strength in the anionic part. A clear red shift is observed between [X-AnMIM][A2] and [X-AnMIM][A3] ILs and isolated anthracene, which is a clear manifestation of the effect of the imidazolium cation on the electronic energy levels of anthracene. It can be expected that the studied ILs are not electrochemically stable during the electrochemistry applications.