The separation of racemates is still a great challenge, since enantiomers commonly exhibit identical physicochemical properties in achiral environments, but differ in biological responses in chiral surroundings. Recently, graphene oxide (GO) based enantionseparation membranes had been proven to follow the facilitated or retarded transport mechanism, dependent on the choice of chiral selectors. Herein, a dipeptide was selected to act as the chiral selector for separating racemates, since it has a longer molecular length than single amino acids and two chiral centers as well, thus more potentially penetrating into the interlayer space in GO membranes. Results show that dipeptide-modified GO membranes exhibit a maximum separation factor of 1.85 with a 1–3 orders of magnitude improved flux in comparison to conventional chiral separation membranes, particularly a reversal of the transport mechanism from facilitated to retarded with respect to GO membranes previously reported. This is a likely consequence of the L-isomeric dipeptide that possesses a much stronger affinity toward the D-isomeric chiral analyte than the L-isomeric one due to the occurrence of extra nonstereoselective interaction between probes and the opposite GO substrate, so that such the dipeptide modified GO membrane exhibits a retarded transport mechanism, thereby offering a promise to achieve the continuous operation. These findings demonstrate that the extra nonstereoselective interaction plays a key role in the chiral recognition, especially in the confined space, and provides new opportunities for controlling the conversion from facilitated to retarded transport mechanisms and designing the novel enantioseparation membranes, aiming at the large-scale production of diversely pure enantiomers.

外消旋体的分离仍然是一个巨大的挑战，因为对映异构体通常在非手性环境中表现出相同的物理化学性质，但在手性环境中的生物反应不同。最近，基于氧化石墨烯 (GO) 的对映体分离膜已被证明遵循促进或延迟传输机制，这取决于手性选择器的选择。在此，选择二肽作为分离外消旋体的手性选择器，因为它的分子长度比单个氨基酸更长，并且还有两个手性中心，因此更有潜力 渗透到 GO 膜的层间空间。结果表明，与传统手性分离膜相比，二肽修饰的 GO 膜的最大分离因子为 1.85，通量提高了 1-3 个数量级，特别是之前的 GO 膜的传输机制从促进到延迟的逆转报道。这可能是L-异构二肽对D-异构手性分析物的亲和力比L-异构二肽强得多的结果。由于探针与相反的GO底物之间发生额外的非立体选择性相互作用而形成-异构体，因此这种二肽修饰的GO膜表现出延迟的传输机制，从而为实现连续操作提供了希望。这些发现表明，额外的非立体选择性相互作用在手性识别中起着关键作用，尤其是在受限空间中，并为控制从促进转运机制到延迟转运机制的转化和设计新型对映体分离膜提供了新的机会，旨在实现大规模生产不同纯度的对映异构体。