Enantioselective Recognition and Separation of C2 Symmetric Substances via Chiral Metal-Organic Frameworks

A promising route toward the enantioselective recognition and separation of racemic molecules is the design of chiral metal-organic frameworks (CMOFs) with high enantioselectivity and stability. Herein, we report porous CMOFs Delta- and Lambda-RuEuMOFs constructed from the D-3-symmetry helical chiral Ru(phen)(3)-derived tricarboxylate ligand and Eu-2 units, which can be utilized as adsorbents for the enantioselective recognition and separation of 1,1'-bi-2-naphthol (BINOL) derivatives. Investigation of the circular dichroism enantiodifferentiation between the host and guest suggested that Delta- and Lambda-RuEu-MOFs can be employed as chiral sensors to discriminate axial enantiomers due to their diastereomeric host-guest relationship. Density functional theory calculations reveal that chiral recognition is attributed to the distinguishing binding affinities stemming from N center dot center dot center dot H-O hydrogen bonds and pi-pi stacking between the host and guest. Moreover, the reticulate structure of Delta- and Lambda-RuEu-MOFs can be readily recycled and reused for the successive enantioselective separation of BINOL up to 80% ee.

Automated summary

The study introduces a promising method for the enantioselective recognition and separation of racemic molecules using designed chiral metal-organic frameworks, showcasing the selective adsorption of BINOL derivatives by Delta- and Lambda-RuEuMOFs and their ability to differentiate enantiomers based on circular dichroism enantiodifferentiation. Density functional theory calculations reveal the crucial role of specific binding affinities between the host and guest in chiral recognition.