气态[HPro（C1）]＋和[Sac]-相互作用及质子转移机制的理论研究

质子化功能离子液体在许多重要领域具有潜在的应用价值，然而人们对其相互作用模式、质子转移行为等方面的认识尚不清晰．本文利用DFT／B3LYP和MP2方法，以脯氨酸阳离子HPro]＋、脯氨酸甲酯阳离子HProC1]＋和糖精阴离子Sac]=组成的质子化离子液体（PILs）为研究对象，探讨气态离子对、分子对、双聚体团簇中的结构单元及其作用模式．利用过渡态和内禀反应坐标（IRC）理论研究气态HPro]＋Sac]-和HProCl]＋Sac]-中的质子转移反应，AIM（atomsinmolecules）理论分析给出氢键相互作用本质等．计算结果表明，气态单聚体中氢转移能垒很小，体系中存在离子对和分子对的动态平衡．质子转移发生后，体系内部基本作用单元改变，作用强度下降，形成分子对的相互作用能量远远小于离子对的相互作用能量．双聚体团簇计算说明体系中没有质子转移反应发生，在HPro]2＋Sac]2-中相互作用的基本结构单元为离子、分子和两性离子，酯化后双聚体HProC1]2＋Sac]2-中全部为阴阳离子相互作用．质子转移反应、两性离子和酯化作用等的深入研究对于理解功能化PILs的性质、结构因素及其应用具有一定的实际意义．

Interaction character and proton transfer mechanism of [HPro（C1）]＋ and [Sac]- in the gas phase： A theoretical study

： While protic ionic liquids （PILs） are today emerging as important materials with an amazing diversity in properties and applications, but not much is known about the detailed interaction mode and the proton transfer mechanism. The amino acid ionic liquids HPro]＋Sac]- and HProCl]＋Sac]- were systematically studied by DFT/B3LYP and MP2 methods with 6-311＋G（d,p） basis set. The stable geometries and interaction modes of the cation, anion, ionic pair, neutral pair, as well as the dimmer HPro]2＋Sac]2 and HProCl]2＋Sac]2 were obtained and characterized. In the single HPro]＋Sac]- and HProCl]＋Sac]- units, proton transfer from cation to anion can be observed and testified by the TS and IRC calculations. The lower energy barriers indicated that there exists the dynamic balance between the ionic pairs and neutral pairs. The interaction intensity between the fragments will significantly be weakened after H-transfer reaction. In the dimmer, proton transfer does not occur. The components are stabilized by completely ionic-ionic interaction in HProCl]a＋Sac]2-, and by jointly ionic-ionic and neutral-zwitterionic interactions in HPro]2＋Sac]2-. The proton transfer, the existence of zwitterion, and the esterification may play important roles in the physicochemical property change of ILs, which have been discussed. The H-bond chemical nature in the single ion-pair and dimmer were analyzed by the theory of atoms in molecules （AIM）.