Chiral transfer amidst one-dimensional linear polymers and twodimensionalnetwork covalent organic frameworks: Striking a finebalance between helicity and crystallinity

Abstract: The   current   landscape   of   chiral   covalent   organic   frameworks   (COFs)   predominantly   centered   on   constructing   asymmetricmolecular-scale   chirality,   often   introducing   an   inherent   contradiction   to   the   COF   symmetry   and   limiting   diversity.   Herein,   weovercome   these   challenges   by   achieving   chiral   transfer between   one-dimensional   (1D) imine   linear polymers   (LPs) and   twodimensional (2D) network β-ketoenamine COFs composed of achiral monomers. We successfully synthesize several 1D imineLPs with   mesoscopic   helical   chirality,   comprising   achiral   C2-symmetric   terephthalaldehyde   and   diamine   linkers   in   a   chiralsupramolecular   transcription   system.   Leveraging   the   irreversible   tautomerism   mechanism   within   the   linker   replacementapproach, terephthalaldehyde (TPA) units in these helical 1D LPs are substituted with C3-symmetric 1,3,5-triformylphloroglucinol(TP), yielding the corresponding 2D network β-ketoenamine COFs. Crystallinity and helicity of the resultant β-ketoenamine COFsintimately   hinge   on   reaction   conditions,   including   the   aldehyde   stoichiometry   of   Tp   and   TPA,   as   well   as   the   quantity   andconcentration   of   the   catalyst   employed.   Under   optimized   conditions,   the   nucleation   and   growth   were   precisely   governed,achieving a harmonious equilibrium of crystallinity and helicity within the generated 2D network β-ketoenamine COFs, even withcovalent bond rupture, recombination, and topological transition (from [C2 + C2] to [C3 + C2]). Impressively, the ground statechirality inherent to helical 1D LPs seamlessly transfers to helical 2D network β-ketoenamine COFs. This study not only offersnew perspectives on the development of chiral functional COFs, but also provides fresh insights into the precise control of COFs'microscopic morphology.

Xinlin Zha, Mengjuan Zuo, Guilin Xu, Zhong Yan, Haining You, Yi Xiong, Ying Liu, Yingying Li, Liyan Yang,Ke Liu, Mufang Li, Tao Zhao, and Dong Wang. Chiral transfer amidst one-dimensional linear polymers and twodimensionalnetwork covalent organic frameworks: Striking a finebalance between helicity and crystallinity . Nano Research. (2024).