We explore the structure of a series of protic Ionic Liquids based on the choline cation and amino acid anions. In the series, the length and the branching of the amino acid alkyl chain varies. Ab initio molecular dynamics, X-ray diffraction measurements, and infrared spectra have been used to provide a reliable picture of the short-range structure and of the short-time dynamic process that characterize the fluids. We have put special emphasis on the peculiar and complicated network of hydrogen bonds that stem from the amphoteric nature of the anion moiety. The use of ab initio molecular dynamics allows us to calculate the “exact” charge density of the system and hence to obtain fairly accurate infrared spectra that, in turn, have been used to assign the experimental ones.

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基于分子动力学模拟的基于胆碱的质子离子液体中的氢键特征

我们探索基于胆碱阳离子和氨基酸阴离子的一系列质子离子液体的结构。在该系列中，氨基酸烷基链的长度和支链变化。从头算分子动力学，X射线衍射测量和红外光谱已用于提供表征流体的短程结构和短时动态过程的可靠图像。我们特别强调了由于阴离子部分的两性而产生的独特而复杂的氢键网络。从头算分子动力学的使用使我们能够计算系统的“精确”电荷密度，从而获得相当准确的红外光谱，进而将其用于分配实验光谱。