Evaluation of characteristics and properties variation of some dianionic ionic liquids (DAILs) upon change on their fluorine atom contents
摘要
Fluorine-containing dianionic liquids (DILs) are under investigation due to their unique properties and potential applications in various fields, especially as excipients in pharmaceutical formulations. In this work, a series of DAILs with terephthalate dianion ([TP]2−) and its fluorinated derivatives ([F1TP]2−, [F2TP]2−(a), [F2TP]2−(b), [F2TP]2−(c), [F3TP]2−, [F4TP]2−) along with functionalized phenylmethylimidazolium cation ([PhMim]+) are introduced. The effect of the number and position of F atoms in the benzene ring of the terephthalate dianion on the structure and some physical and chemical properties of this class of DAILs are evaluated using the density functional theory (DFT) at M06-2X-GD3/AUG-cc-pVDZ level of theory. Electrostatic potential (ESP) maps, the interaction energies, thermodynamic parameters, the changes in vibrational frequencies, structures parameters, electronic and topological properties and RDG analysis of the DAILs were studied. The corrected interaction energies between the dianions and the two cations are -245.61, -243.16, -244.42, -241.96, -242.85, -240.51, -238.00, -238.96 and -235.82 kcal mol−1 for the ion triplets (ITs) of [PhMim]2[TP], [PhMim]2[F1TP](a), [PhMim]2[F1TP](b), [PhMim]2[F2TP](a), [PhMim]2[F2TP](b), [PhMim]2[F2TP](c), [PhMim]2[F3TP](a), [PhMim]2[F3TP](b), [PhMim]2[F4TP], respectively. The results show that the fluorination of the six-membered ring of the terephthalate dianion reduces the interaction energies between the dianions and cations in the proposed ITs and can lead to introduce some DAILs with lower melting points and higher ionic conductivity. Also, the electrochemical window of this class of DAILs is estimated to be in the range of 2.38 to 3.28 V in acetonitrile solvent.