State Key Laboratory of Chemical Engineering and School of Chemistry & Molecular Engineering, East China University of Science and Technology, Shanghai, China.
Chirality. 2020 Jun;32(6):842-853. doi: 10.1002/chir.23190. Epub 2020 Feb 19.
Up to date, functionalized graphene-based membranes have exhibited a promising potential in the enantioseparation. However, since precisely controlling the interlayer distance of two-dimensional materials is a great challenge in practical experiments, the transport mechanism of chiral guests in such membranes, together with various critical parameters that play a controlling role in the transport behaviors of the preferentially binding enantiomer in narrow channels, remains to be explored. The molecular dynamics (MD) simulation, especially using the steered MD (SMD) method, might be an alternative way to investigate the enantioseparation processes and mechanisms of layered membranes with different interlayer distances. In this work, D-alanine modified graphene sheets with different interlayer distances were built as membrane models, whereas D- and L-phenylalanine were selected as chiral probes. The effect of the interlayer distance and the applied external force on the enantioseparation performance was examined. Results show that such two parameters exert a significant influence on the enantioseparation performance: (a) Increasing the interlayer distance would result in a conversion from the retarded to the facilitated mechanism at a proper external force (medium); (b) both the large and small driving forces would only lead to the appearance of the retarded transport for the preferential enantiomer, unlike the moderate force; (c) the interaction energy of L-phenylalanine with D-isomer selector decreases with the rising interlayer distances studied in this work, regardless of what the external force is. Our findings can provide guidance on the practical applications in the membrane-based chiral separation.
迄今为止，功能化石墨烯基膜在对映体分离中表现出了巨大的应用潜力。然而，由于在实际实验中精确控制二维材料的层间距是一个巨大的挑战，因此手性客体在这类膜中的传输机制以及在窄通道中优先结合对映体的传输行为中起控制作用的各种关键参数仍然需要探索。分子动力学（MD）模拟，尤其是使用导向 MD（SMD）方法，可能是研究具有不同层间距的层状膜的对映体分离过程和机制的一种替代方法。在这项工作中，构建了具有不同层间距的 D-丙氨酸修饰的石墨烯片作为膜模型，而 D-和 L-苯丙氨酸则被选为手性探针。考察了层间距和外加外力对对映体分离性能的影响。结果表明，这两个参数对分离性能有显著影响：（a）在适当的外力（中等）下，增加层间距会导致从阻滞机制转变为促进机制；（b）无论是大的还是小的驱动力，只会导致优先对映体的阻滞传输，而不是中等力；（c）无论外加力如何，L-苯丙氨酸与 D-异构体选择器的相互作用能随研究中层间距的增加而降低。我们的研究结果可以为基于膜的手性分离的实际应用提供指导。
