Challenges and opportunities for chiral covalent organic frameworks

Abstract

As highly versatile crystalline porous materials, covalent organic frameworks (COFs) have emerged as an ideal platform for developing novel functional materials, attributed to their precise tunability of structure and functionality....

Chiral probes for biosensing

“…Chiral COFs have also been used for enantioselective sensing. [117][118][119] For instance, Cui's group incorporated optically pure 1,1 0 -bi-2-naphthol (BINOL) into COFs for enantioselective processes. 119 Through careful design and selection of building blocks, the researchers successfully synthesized two iminelinked chiral fluorescent COFs with a 2D layered hexagonal or tetragonal structure.…”

Bottom–Up Design of Photoactive Chiral Covalent Organic Frameworks for Visible-Light-Driven Asymmetric Catalysis

“…Meanwhile, catalytic sites of COF catalysts are fully exposed to reactants to achieve high activity and stereoselectivity. In particular, the construction of chiral COFs (CCOFs) with homochiral building blocks through direct synthetic or post-synthetic strategies endows them with superior performance in asymmetric catalysis. − However, it is still quite challenging to develop CCOFs because of the conflict between the rigidity of crystalline skeletons and the flexibility of chiral functional groups. There are a few examples in the literature focusing on the combination of semiconducting COFs with chiral molecular catalysts or the utilization of copper–porphyrin building blocks bearing metal species .…”

Engineering UiO-68-Typed Homochiral Metal–Organic Frameworks for the Enantiomeric Separation of Fmoc-AAs and Mechanism Study

“…Chirality is an essential feature of various life processes. As chiral compounds get increasingly paramount in the fields of life sciences, pharmaceuticals, and food additives, the demand for chiral compounds is growing explosively. − At present, most of the synthetic chiral substances are racemates, and their two enantiomers may have completely different biological activities and pharmacological effects. − As a consequence, for the application of almost all racemates, it is imperative to seek effective enantiomeric resolution. − Nonetheless, owing to the dramatic similarity of the physicochemical properties of two enantiomers, enantiomeric separation has always been a difficult point in the fields of separation science, chemistry, and pharmacy. , In the past few decades, extensive efforts have been made to develop chiral porous materials for efficient enantiomeric separation. − Usually, enantioselective separation using chiral porous materials as adsorbents requires tailored and diverse chiral pore environments to efficiently interact with chiral substrates. ,, In recent years, homochiral metal–organic frameworks (HMOFs) with open pores/channels have drawn great attention for separation of chiral molecules due to their diversity in structure and pore size, tailored chiral pore environments, and selective adsorption affinity, enabling strong interactions with chiral substrates. − An excellent HMOF adsorbent to qualify for enantiomeric separation targets should at least simultaneously possess three features: (a) robust structure with high stability, (b) open and accessible pores, and (c) chiral environment with binding sites. Nevertheless, most of the HMOFs reported have weak chemical stability and small cavity size, which immensely limits their practical applications. − Therefore, the design and synthesis of HMOFs with excellent stability and large cavities lined with binding sites is the key to develop advanced enantioselective separation materials.…”