State Key Laboratory of Chemical Engineering and School of Chemistry & Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P.R. China.
National Engineering Laboratory for Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, Yunnan province, China.
ACS Appl Mater Interfaces. 2020 Mar 4;12(9):10893-10901. doi: 10.1021/acsami.0c00898. Epub 2020 Feb 21.
Graphene oxide (GO)-based membranes have displayed superior performances in the chiral resolution compared with conventional polymer-based and inorganic membranes. However, the effect of the host-guest interaction between chiral selectors and probes on the enantioseparation properties of GO-based membranes remains to be established. In this work, l-phenylalanine (l-Phe, as the chiral selector)-modified GO-based (l-Phe-GO) membranes were fabricated, and their enantioseparation performances toward various enantiomers, that is, d- and l-phenylalanine (d- and l-Phe), d- and l-methionine (d- and l-Met), -acyl-d-phenylalanine (-acyl-d-Phe) and -acyl-l-phenylalanine (-acyl-l-Phe), and -acyl-d-methionine (-acyl-d-Met) and -acyl-l-methionine (-acyl-l-Met), were detected. Results show that (i) l-Phe is preferential to transport d-enantiomers relative to l-enantiomers; (ii) as far as d-enantiomers are concerned, the d-Phe-like enantiomers move faster than d-Met-like ones through the l-Phe-GO membrane owing to their different host-guest interactions. The strength of interactions between chiral selectors and probes was further confirmed from both experimental and theoretical standpoints. In the former case, the enantioselective adsorption of l-Phe-GO nanosheets toward the aforementioned enantiomers demonstrates that l-Phe delivers a higher adsorption capacity to d-enantiomers relative to l-enantiomers, and meanwhile, d-Phe-like enantiomers are better than d-Met-like enantiomers in the adsorption capacity. In the latter case, the chiral separation mechanism is clarified using the periodical density functional theory (DFT) calculation, indicating that l-Phe interacts with d-enantiomers more strongly than l-enantiomers. Especially, our calculations unveil that the difference in the interaction strength is principally dominated by the nonstereoselective interactions between chiral probes and the GO surface. Therefore, our findings suggest that the nonstereoselective weak interaction can be employed to improve the enantioselectivity of GO-based membranes.
基于氧化石墨烯（GO）的膜在对映体拆分方面的表现优于传统的聚合物基和无机膜。然而，手性选择剂与探针之间的主客体相互作用对基于 GO 的膜的对映体分离性能的影响仍有待建立。在这项工作中，制备了 L-苯丙氨酸（L-Phe，作为手性选择剂）修饰的基于 GO 的（L-Phe-GO）膜，并检测了它们对各种对映体，即 D-和 L-苯丙氨酸（D-和 L-Phe）、D-和 L-蛋氨酸（D-和 L-Met）、-酰基-D-苯丙氨酸（-酰基-D-Phe）和 -酰基-L-苯丙氨酸（-酰基-L-Phe）以及 -酰基-D-蛋氨酸（-酰基-D-Met）和 -酰基-L-蛋氨酸（-酰基-L-Met）的对映体分离性能。结果表明：（i）L-Phe 优先于 D-对映体相对于 L-对映体进行传输；（ii）就 D-对映体而言，由于不同的主客体相互作用，D-Phe 样对映体比 D-Met 样对映体更快地通过 L-Phe-GO 膜移动。从实验和理论两个方面进一步证实了手性选择剂和探针之间相互作用的强度。在前者情况下，L-Phe-GO 纳米片对上述对映体的对映选择性吸附表明，L-Phe 对 D-对映体的吸附容量高于 L-对映体，同时，D-Phe 样对映体的吸附容量优于 D-Met 样对映体。在后一种情况下，使用周期性密度泛函理论（DFT）计算阐明了手性分离机制，表明 L-Phe 与 D-对映体的相互作用强于 L-对映体。特别是，我们的计算揭示了相互作用强度的差异主要由手性探针与 GO 表面之间的非立体选择性相互作用决定。因此，我们的研究结果表明，可以利用非立体选择性弱相互作用来提高基于 GO 的膜的对映体选择性。
