Ortho-Alkoxy-benzamide Directed Formation of a Single Crystalline Hydrogen-bonded Crosslinked Organic Framework and Its Boron Trifluoride Uptake and Catalysis.

Boron trifluoride (BF3 ) is a highly corrosive gas widely used in industry. Confining BF3 in porous materials ensures safe and convenient handling and prevents its degradation. Hence, it is highly desired to develop porous materials with high adsorption capacity, high stability, and resistance to BF3 corrosion. Herein, we designed and synthesized a Lewis basic single-crystalline hydrogen-bond crosslinked organic framework (HC OF-50) for BF3 storage and its application in catalysis. Specifically, we introduced self-complementary ortho-alkoxy-benzamide hydrogen-bonding moieties to direct the formation of highly organized hydrogen-bonded networks, which were subsequently photo-crosslinked to generate HC OFs. The HC OF-50 features Lewis basic thioether linkages and electron-rich pore surfaces for BF3 uptake. As a result, HC OF-50 shows a record-high 14.2 mmol/g BF3 uptake capacity. The BF3 uptake in HC OF-50 is reversible, leading to the slow release of BF3 . We leveraged this property to reduce the undesirable chain transfer and termination in the cationic polymerization of vinyl ethers. Polymers with higher molecular weights and lower polydispersity were generated compared to those synthesized using BF3 ⋅ Et2 O. The elucidation of the structure-property relationship, as provided by the single-crystal X-ray structures, combined with the high BF3 uptake capacity and controlled sorption, highlights the molecular understanding of framework-guest interactions in addressing contemporary challenges.

A Heteromeric Carboxylic Acid Based Single-Crystalline Crosslinked Organic Framework.

The development of large pore single-crystalline covalently linked organic frameworks is critical in revealing the detailed structure-property relationship with substrates. One emergent approach is to photo-crosslink hydrogen-bonded molecular crystals. Introducing complementary hydrogen-bonded carboxylic acid building blocks is promising to construct large pore networks, but these molecules often form interpenetrated networks or non-porous solids. Herein, we introduced heteromeric carboxylic acid dimers to construct a non-interpenetrated molecular crystal. Crosslinking this crystal precursor with dithiols afforded a large pore single-crystalline hydrogen-bonded crosslinked organic framework HC OF-101. X-ray diffraction analysis revealed HC OF-101 as an interlayer connected hexagonal network, which possesses flexible linkages and large porous channels to host a hydrazone photoswitch. Multicycle Z/E-isomerization of the hydrazone took place reversibly within HC OF-101, showcasing the potential use of HC OF-101 for optical information storage.