Enantioselective adsorption and diffusion of S-/R-glycidol in homochiral zeolites: A molecular simulation study

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• 作者：Liling Zhang ; Jianwen Jiang
• 关键词：Enantiomers ; Adsorption ; Diffusion ; Glycidol ; Homochiral zeolites
• 刊名：Journal of Membrane Science
• 出版年：2011
• 出版时间：1 February 2011
• 年：2011
• 卷：367
• 期：1-2
• 页码：63-70
• 全文大小：994 K

文摘

As the first example of enantiopure homochiral zeolites, silicogermanates SU-32 can be synthesized in right- (SU-32a) or left-handed (SU-32b). These rare chiral zeolites provide beautiful benchmark structures to examine the microscopic properties of chiral molecules in the helical channels with only a single handedness. We report a molecular simulation study to investigate the enantioselective adsorption and diffusion of S-/R-glycidol enantiomers in SU-32a and SU-32b. S-glycidol is found to interact with SU-32a more strongly than R-glycidol and preferentially adsorbed in SU-32a, and the opposite is observed in SU-32b. The enantiomeric excess of S-/R-glycidol racemic mixture in SU-32a and SU-32b is up to 25 % and slightly decreases with increasing temperature. For pure enantiomers, S-glycidol diffuses faster in SU-32a and slower in SU-32b, whereas the reverse is true for R-glycidol. The free energy analysis suggests that S-glycidol encounters a lower barrier to diffuse in SU-32a but a higher one in SU-32b. For S-/R-glycidol racemic mixture, the diffusion difference between two enantiomers becomes negligible as loading increases. This study reveals that enantiopure SU-32a and SU-32b have distinct enantioselectivity for glycidol enantiomers, particularly the selective adsorption, and might be useful for chiral separation.