3 research outputs found

    Fast, Ambient Temperature and Pressure Ionothermal Synthesis of Three-Dimensional Covalent Organic Frameworks

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    Covalent organic frameworks (COFs) are an emerging class of porous crystalline polymers with wide range of potential applications. However, the availability of three-dimensional (3D) COFs is still limited, and their synthesis is confined to the high-temperature solvothermal method. Here, we report for the first time a general and simple strategy to produce a series of 3D ionic liquid (IL)-containing COFs (3D-IL-COFs) by using IL as a green solvent. The syntheses are carried out at ambient temperature and pressure accompanied by a high reaction speed (e.g., only three mins for 3D-IL-COF-1), and the IL can be reused without activity loss. Furthermore, the 3D-IL-COFs show impressive performance in the separation of CO<sub>2</sub>/N<sub>2</sub> and CO<sub>2</sub>/CH<sub>4</sub>. This research thus presents a potential pathway to green large-scale industrial production of COFs

    Three-Dimensional Ionic Covalent Organic Frameworks for Rapid, Reversible, and Selective Ion Exchange

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    Covalent organic frameworks (COFs) have emerged as functional materials for various potential applications. However, the availability of three-dimensional (3D) COFs is still limited, and nearly all of them exhibit neutral porous skeletons. Here we report a general strategy to design porous positively charged 3D ionic COFs by incorporation of cationic monomers in the framework. The obtained 3D COFs are built of 3-fold interpenetrated diamond net and show impressive surface area and CO<sub>2</sub> uptakes. The ion-exchange ability of 3D ionic COFs has been highlighted by reversible removal of nuclear waste model ions and excellent size-selective capture for anionic pollutants. This research thereby provides a new perspective to explore 3D COFs as a versatile type of ion-exchange materials

    Structural Conjugation Tuning in Covalent Organic Frameworks Boosts Charge Transfer and Photocatalysis Performances

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    Structural conjugation greatly affects the optical and electronic properties of the COF photocatalyst. Herein, we show that 2D hydrazone COFs with either π-extended biphenyl (BPh–COF) or acetylene (AC–COF) frameworks demonstrated distinct charge transfer and photocatalytic performances. The two COFs show good crystallinity and decent porosity as their frameworks are enforced by intra/interlayers hydrogen bonding. However, computational and experimental data reveal that AC–COF managed broader visible-light absorption and narrower optical bandgaps and performed efficient photoinduced charge separation and transfer in comparison with BPh–COF, meaning that the ethynyl skeleton with enhanced planarity better improves the π-conjugation of the whole structure. As a result, AC–COF exhibited an ideal bandgap for rapid oxidative coupling of amines under visible-light irradiation. Furthermore, taking advantage of its better charge transfer properties, AC–COF demonstrated considerable enhanced product conversion and notable functional tolerance for metallaphotocatalytic C–O cross-coupling of a wide range of both aryl bromides and chlorides with alcohols. More importantly, besides being recoverable, AC–COF showcased the previously inaccessible etherification of dihaloarene. This report shows a facile approach for manipulating the structure–activity relationship and paves the way for the development of a COF photocatalyst for solar-to-chemical energy conversion