Low Kaycee, Tan Samuel Y S, Izgorodina Ekaterina I
Monash Computational Chemistry Group, School of Chemistry, Monash University, Melbourne, VIC, Australia.
Front Chem. 2019 Apr 10;7:208. doi: 10.3389/fchem.2019.00208. eCollection 2019.
Unlike typical hydrogen-bonded networks such as water, hydrogen bonded ionic liquids display some unusual characteristics due to the complex interplay of electrostatics, polarization, and dispersion forces in the bulk. Protic ionic liquids in particular contain close-to traditional linear hydrogen bonds that define their physicochemical properties. This work investigates whether hydrogen bonded ionic liquids (HBILs) can be differentiated from aprotic ionic liquids with no linear hydrogen bonds using state-of-the-art calculations. This is achieved through geometry optimizations of a series of single ion pairs of HBILs in the gas phase and an implicit solvent. Using benchmark CCSD(T)/CBS calculations, the electrostatic and dispersion components of the interaction energy of these systems are compared with those of aprotic ionic liquids. The inclusion of the implicit solvent significantly influenced geometries of single ion pairs, with the gas phase shortening the hydrogen bond to reduce electrostatic interactions. HBILs were found to have stronger interactions by at least 10EtMeNH0 kJ mol over aprotic ILs, clearly highlighting the electrostatic nature of hydrogen bonding. Geometric and energetic parameters were found to complement each other in determining the extent of hydrogen bonding present in these ionic liquids.
与典型的氢键网络（如水）不同，氢键离子液体由于本体中静电、极化和色散力的复杂相互作用而呈现出一些不寻常的特性。质子离子液体尤其包含接近传统的线性氢键，这些氢键决定了它们的物理化学性质。这项工作使用最先进的计算方法研究了氢键离子液体（HBILs）是否可以与没有线性氢键的非质子离子液体区分开来。这是通过对气相和隐式溶剂中一系列HBILs单离子对进行几何优化来实现的。使用基准CCSD(T)/CBS计算，将这些体系相互作用能的静电和色散分量与非质子离子液体的进行比较。隐式溶剂的加入显著影响了单离子对的几何结构，气相中氢键缩短以减少静电相互作用。发现HBILs的相互作用比非质子离子液体至少强10EtMeNH0 kJ mol，清楚地突出了氢键的静电性质。发现几何和能量参数在确定这些离子液体中存在的氢键程度方面相互补充。
