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Homochiral Covalent Organic Frameworks with Superhelical Nanostructures Enable Efficient Chirality-Induced Spin Selectivity. | LitMetric

Homochiral Covalent Organic Frameworks with Superhelical Nanostructures Enable Efficient Chirality-Induced Spin Selectivity.

Angew Chem Int Ed Engl

School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 200240, Shanghai, China.

Published: December 2024

AI Article Synopsis

  • Researchers have developed a method to create homochiral superhelical covalent organic frameworks (COFs) by adjusting the lengths of alkyl chains in organic linkers.
  • These COFs, specifically COF-13-OEt, form distinct right- and left-handed superhelical fibers due to optimal ethoxyl substituents, while other variants exhibit different shapes.
  • The superhelical structures enhance their chiral recognition abilities, demonstrating significantly better enantioselectivity in binding carbohydrates and exhibiting notable chiral-induced spin selectivity compared to non-helical structures.

Article Abstract

Despite significant advancements in fabricating covalent organic frameworks (COFs) with diverse morphologies, creating COFs with superhelical nanostructures remains challenging. We report here the controlled synthesis of homochiral superhelical COF nanofibers by manipulating pendent alkyl chain lengths in organic linkers. This approach yields homochiral 3D COFs 13-OR with a 10-fold interpenetrated diamondoid structure (R=H, Me, Et, Pr, Bu) from enantiopure 1,1'-bi-2-naphthol (BINOL)-based tetraaldehydes and tetraamine. COF-13-OEt exhibits macroscopic chirality as right-handed and left-handed superhelical fibers, whereas others adopt spherical or non-helical morphologies. Time-tracking shows a self-assembly process from non-helical strands to single-stranded helical fibers and intertwined superhelices. Ethoxyl substituents, being of optimal size, balance solvophobic effects and intermolecular interactions, driving the formation of superhelical nanostructures, with handedness determined by BINOL chirality. The superhelical nature of these materials is evident in their chiral recognition and spin-filter properties, showing significantly improved enantiodiscrimination in carbohydrate binding (up to six times higher enantioselectivity) and a remarkable chiral-induced spin selectivity (CISS) effect with a 48-51 % spin polarization ratio, a feature absent in non-helical analogs.

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Source
http://dx.doi.org/10.1002/anie.202412380DOI Listing

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