Multifunctional Porous Hydrogen-Bonded Organic Frameworks: Current Status and Future Perspectives

Abstract

Hydrogen-bonded organic frameworks (HOFs), self-assembled from organic or metalated organic building blocks (also termed as tectons) by hydrogen bonding, π−π stacking, and other intermolecular interactions, have become an emerging class of multifunctional porous materials. So far, a library of HOFs with high porosity has been synthesized based on versatile tectons and supramolecular synthons. Benefiting from the flexibility and reversibility of H-bonds, HOFs feature high structural flexibility, mild synthetic reaction, excellent solution processability, facile healing, easy regeneration, and good recyclability. However, the flexible and reversible nature of H-bonds makes most HOFs suffer from poor structural designability and low framework stability. In this Outlook, we first describe the development and structural features of HOFs and summarize the design principles of HOFs and strategies to enhance their stability. Second, we highlight the state-ofthe-art development of HOFs for diverse applications, including gas storage and separation, heterogeneous catalysis, biological applications, sensing, proton conduction, and other applications. Finally, current challenges and future perspectives are discussed.

Robust {Cd4}-Organic Framework for Efficiently Catalyzing CO2 Cycloaddition and Knoevenagel Condensation

“…In addition, with the rapid economic development and population explosion, the rapidly increasing consumption of fossil fuels has brought about a series of negative impacts. , For example, the release of massive amounts of carbon dioxide (CO 2 ) into the atmosphere has triggered the global greenhouse effect, greatly affecting human survival and development. , Therefore, research on reducing the content of CO 2 in the atmosphere and converting it into clean energy has important significance. Currently, there have been numerous reports on transforming CO 2 into high-value-added products, mainly in the fields of photochemical products, fine chemical products, and polymeric materials. − Among the many chemicals prepared from CO 2 , the preparation of cyclic carbonates is one of the most promising ways to achieve industrial application prospects for the utilization of CO 2 . Due to the advantages of high boiling point, large polarity, stable properties, safety, and nontoxicity, cyclic carbonates have very wide applications, such as intermediates of fine chemical products, polar aprotic solvents, lithium-ion battery electrolytes, and so on. − To date, many heterogeneous and homogeneous catalysts have successfully been applied to the synthesis of cyclic carbonates, mainly including common organic small molecules (ionic liquids, organic bases, etc.…”

Hierarchical porous photosensitizers with efficient photooxidation

“…Due to the existence of very ordered pyridines on the porous surface, these perforated laminates could easily cross-link with 1,4-bis(bromomethyl)benzene (BBMB), resulting in the hydrogen-bonded porous frameworks (HOFs) (Supplementary Fig. 12 ) 40 . As shown in Supplementary Figure 13 , there exists a periodical diffraction with 2 θ ≈ 6.8° in the experimental PXRD pattern of the HOF1 and HOF2 based on the polymerization of 1:1 and 1:5 co-assembles.…”

A two-dimensional luminescent HOF containing an interpenetrating network structure with dual function: highly sensitive detection of methotrexate and multi-level information encryption

“…Hydrogen bonds are weak and reversible in comparison to covalent and coordination bonds. Thus, HOF materials have certain distinct advantages, such as softer preparation conditions, 13 better solution processing performance, 14 and greater biocompatibility. 15 In the majority of HOF cases, the carboxyl and amino groups on organic building blocks promote the formation of hydrogen bonds, however, reports of HOFs relying on heterocyclic groups to establish hydrogen bonds are rare.…”