Robust Mesoporous Functional Hydrogen-Bonded Organic Framework for Hypochlorite Detection

Abstract

Although tremendous progress has been achieved in the field of hydrogen-bonded organic frameworks (HOFs), the low stability, small/none pores, and difficult functionality severely obstruct their development. Herein, a novel robust mesoporous HOF (HOF-FAFU-1) decorated with a high density of free hydroxy moieties has been designed and readily synthesized in the de novo synthesis. In HOF-FAFU-1, the planar building blocks are connected to each other by typical intermolecular carboxylate dimers to form two-dimensional (2D) layers with sql topology, which are further connected to their adjacent layers by face-to-face π−π interactions to obtain a three-dimensional (3D) open mesoporous framework. Owing to the high density of intermolecular hydrogen bonding and strong π−π interactions, HOF-FAFU-1 is very stable, allowing it to retain its structure in aqueous solutions with a pH range of 1−9. Benefiting from the decorated hydroxy moieties, HOF-FAFU-1 was exploited as a fluorescent sensor for hypochlorite detection in water media by a turn-off mode, which cannot be realized by its nonhydroxy groups anchoring counterpart (HOF-TCBP). The proposed sensing system is highly efficient, validated by a very broad linear range (0−0.45 mM), fast response (15 s), and small limit of detection (LOD) (1.32 μM). The fluorescent quenching of HOF-FAFU-1 toward hypochlorite was also investigated, mainly being ascribed to the transformation of building blocks from the fluorescent reduced state to the nonfluorescent oxidative state. This work not only demonstrates that HOFs integrated with high stability and large pores as well as high density of functional groups can be simultaneously realized by judicious design of building blocks but also conceptually elucidates that such HOFs can effectively extend the application fields of HOFs.

Bifunctional {Pb10K2}–Organic Framework for High Catalytic Activity in Cycloaddition of CO2 with Epoxides and Knoevenagel Condensation

“…Metal–organic frameworks (MOFs), as a novel crystalline hybrid material self-assembled from versatile inorganic secondary building units (SBUs) and functional organic linkers, have attracted widespread attention because of the promising applications in the fields of gas storage/separation, heterogeneous catalysis, energy harvesting, air and water purification, biomedicine, etc. − In general, the nature of the metal ions in inorganic SBUs is essential for the final structures and target properties of the self-assembled MOFs. However, only transition- or lanthanide-based MOFs at present have been well-established and intensively studied. − By contrast, main group metals in the areas of s- and p-block are not paid much attention yet except for the limited reports on the hard acidic cations of Al 3+ , In 3+ , and Mg 2+ , − which should be attributed to the nonclassical coordination and flexible geometry.…”

Fluorine-Functionalized NbO-Type {Cu2}-Organic Framework: Enhanced Catalytic Performance on the Cycloaddition Reaction of CO2 with Epoxides and Deacetalization-Knoevenagel Condensation

“…Metal–organic frameworks (MOFs), as a trending type of hybrid material besides zeolite and carbon nanotubes, are confirmed to have a wide range of applications in the fields of adsorption, , separation, − sensing, and catalysis − because of their highly fine-tuning structures, which can be realized by regulating the inorganic secondary building units (SBUs) and organic linkers. However, it is still a tremendous challenge for accurately designing and controlling the microstructure of MOF materials, by which the density of active sites and the intrinsic activity of active sites can be hoisted.…”

Exploring Multifunctional Hydrogen-Bonded Organic Framework Materials

“…By virtue of pore engineering strategy based on reticular chemistry, we constructed a robust mesoporous HOF (HOF-FAFU-1) by judiciously choosing the molecular building blocks with free functional groups and large π-conjugated system (Figure ). Interestingly, benefiting from the reserved hydroxyl functional site, HOF-FAFU-1 exhibits highly efficient turn-off fluorescent sensing of hypochlorite (ClO – ) in aqueous solution, featuring with broad linear range, fast response, and low detection limit. In contrast, the counterpart (HOF-TCBP) without anchoring – OH groups did not show such fluorescence sensing phenomenon.…”

“…(b) Fluorescence responses of HOF-FAFU-1 and HOF-TCBP to hypochlorite (ClO – ). Reprinted with permission from ref . Copyright 2022 American Chemical Society.…”

“…50 By virtue of pore engineering strategy based on reticular chemistry, we constructed a robust mesoporous HOF (HOF-FAFU-1) by judiciously choosing the molecular building blocks with free functional groups and large π-conjugated system (Figure 14). 45 Interestingly, benefiting from the reserved hydroxyl functional site, HOF-FAFU-1 exhibits highly…”