Proton Transfer in Phosphoric Acid-Based Protic Ionic Liquids: Effects of the Base
Proton Transfer in Phosphoric Acid-Based Protic Ionic Liquids: Effects of the Base
复制标题
磷酸基质子离子液体中的质子转移：碱的影响
DOI：
10.1021/acs.jpca.0c02863
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Paddison, Stephen J.
中科院分区：
文献类型：
--
作者：
Zhu, Zhenghao;Luo, Xubo;Sokolov, Alexei P.;Paddison, Stephen J.
电子结构计算是为了理解最近报道的质子离子液体(PILs)的高度去耦合电导。为了在分子水平上理解PILS中的质子电导机制，在B3LYP/6-311G**理论水平上，结合隐式溶剂化模型(ε=61)，计算了三甲胺、咪唑、利多卡因和肌酐(CRT)与一到三个磷酸(PA)分子的最小能量结构。在相似的理论水平上计算了碱基的质子亲和力和零点能量校正结合能。由于碱(质子受体)的较强碱性和高介电常数溶剂稳定电荷分离的作用，在所有体系中都会发生质子从PA解离，从而形成离子对。第二个和第三个PA分子优先相互形成环状氢键，而不是在碱基的给体和受体位置形成氢键。势能扫描显示，质子亲和力较强的碱基对PA分子间质子转移的能量学影响较大。然而，当从双势垒转移到单势垒时，影响是最小的。在含有几个PA分子的CRT体系中观察到了无障碍的质子转移，这意味着CRT可能是一种很有前途的PA基PIL。
Electronic structure calculations were performed to understand highly decoupled conductivities recently reported in protic ionic liquids (PILs). To develop a molecular-level understanding of the mechanisms of proton conductivity in PILs, minimum-energy structures of trimethylamine, imidazole, lidocaine, and creatinine (CRT) with the addition of one to three phosphoric acid (PA) molecules were determined at the B3LYP/6-311G** level of theory with the inclusion of an implicit solvation model (SMD with ε = 61). The proton affinity of the bases and zero-point energy corrected binding energies were computed at a similar level of theory. Proton dissociation from PA occurs in all systems, resulting in the formation of ion pairs due to the relatively strong basicity of the bases (proton acceptors) and the effect of the high dielectric constant solvent in stabilizing the charge separation. The second and third PA molecules preferentially form “ring-like” hydrogen bonds with one another instead of forming hydrogen bonds at the donor and acceptor sites of the bases. Potential energy scans reveal that the bases with stronger proton affinity exert greater influence on the energetics of proton transfer between the individual PA molecules. However, the effects are minimal when shifted into a single-well from a double-well potential. Barrierless proton transfer was observed to occur in the CRT system with several PA molecules present, implying that the CRT may be a promising PA-based PIL.