Single-Step Solution-Phase Synthesis of Free-Standing Two-Dimensional Polymers and Their Evolution into Hollow Spheres

Zhou, Tian; Lin, Feng; Li, Zhan‐Ting; Zhao, Xin

doi:10.1021/ma401570g

Cited by 108 publications

(89 citation statements)

References 35 publications

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“…The SEM images show that the two COFs exist as spherical particles of different sizes, some of which are interconnected. [51][52][53] To the best of our knowledge, this is the first example of hollow spherical COFs having hierarchically porous shells. Interestingly, the SEM image of SIOC-COF-4 shows that the surfaces of the spheres are covered with flakes,w hich have never been observedi nt he morphologies of other COFs before.…”

Section: Resultsmentioning

confidence: 85%

Precision Construction of 2D Heteropore Covalent Organic Frameworks by a Multiple‐Linking‐Site Strategy

Qian

Jiang

et al. 2016

Chemistry A European J

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Integrating different kinds of pores into one covalent organic framework (COF) endows it with hierarchical porosity and thus generates a member of a new class of COFs, namely, heteropore COFs. Whereas the construction of COFs with homoporosity has already been well developed, the fabrication of heteropore COFs still faces great challenges. Although two strategies have recently been developed to successfully construct heteropore COFs from noncyclic building blocks, they suffer from the generation of COF isomers, which decreases the predictability and controllability of construction of this type of reticular materials. In this work, this drawback was overcome by a multiple-linking-site strategy that offers precision construction of heteropore COFs containing two kinds of hexagonal pores with different shapes and sizes. This strategy was developed by designing a building block in which double linking sites are introduced at each branch of a C -symmetric skeleton, the most widely used scaffold to construct COFs with homogeneous porosity. This design provides a general way to precisely construct heteropore COFs without formation of isomers. Furthermore, the as-prepared heteropore COFs have hollow-spherical morphology, which has rarely been observed for COFs, and an uncommon staggered AB stacking was observed for the layers of the 2D heteropore COFs.

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Section: Resultsmentioning

confidence: 85%

Precision Construction of 2D Heteropore Covalent Organic Frameworks by a Multiple‐Linking‐Site Strategy

Qian

Jiang

et al. 2016

Chemistry A European J

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“…Although numerous COF powder exfoliation methods have been reported, very few of these studies demonstrate the ability to reconstitute the resulting nanosheets into large‐area COF films . Most reported methods involve either sonicating the powders in organic solvents or mechanically grinding the powders prior to dispersion, but due to challenges with re‐aggregation and sedimentation at high concentrations, these strategies typically produce dilute suspensions (≤0.2 mg mL −1 ) that are not conducive to large‐scale film fabrication . Although Tsuru and co‐workers demonstrated that thin films can be prepared from a dilute suspension (0.15 mg mL −1 ) of COF‐1 powder prepared through sonication in dichloromethane, the fabrication process required repeated drop‐casting/drying cycles to form a continuous film, and therefore lacks scalability and practicality .…”

Section: Introductionmentioning

confidence: 99%

Acid Exfoliation of Imine‐linked Covalent Organic Frameworks Enables Solution Processing into Crystalline Thin Films

et al. 2020

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Covalent organic frameworks (COFs) are highly modular porous crystalline polymers that are of interest for applications such as charge‐storage devices, nanofiltration membranes, and optoelectronic devices. COFs are typically synthesized as microcrystalline powders, which limits their performance in these applications, and their limited solubility precludes large‐scale processing into more useful morphologies and devices. We report a general, scalable method to exfoliate two‐dimensional imine‐linked COF powders by temporarily protonating their linkages. The resulting suspensions were cast into continuous crystalline COF films up to 10 cm in diameter, with thicknesses ranging from 50 nm to 20 μm depending on the suspension composition, concentration, and casting protocol. Furthermore, we demonstrate that the film fabrication process proceeds through a partial depolymerization/repolymerization mechanism, providing mechanically robust films that can be easily separated from their substrates.

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“…[25][26][27] Although the substrate supported COF films are convenient for investigating the property of COFs, the conductive nature of these substrates can largely interface with the intrinsic electronic measurements of COF 4 films and limit their further applications. More efforts should be made to explore appropriate substrates for COF films growth.…”

Section: Introductionmentioning

confidence: 99%

Selective Growth of Covalent Organic Framework Ultrathin Films on Hexagonal Boron Nitride

Sun

Dong

et al. 2016

J. Phys. Chem. C

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Incorporating the intriguing covalent organic framework (COF) into devices and performing their advanced electronic nature are still challenging. Herein, we demonstrate the direct growth of 2D full-conjugated COF ultrathin films on dielectric hexagonal boron nitride (hBN) for the first time and study the carrier transporting characteristics of π-conjugated COF films. Under the optimized solvothermal conditions, few-layered COF-366 films with the covalent connection of tetra(p-aminophenyl)porphyrin and terephthaladehyde are selectively fabricated on mechanically exfoliated hBN flakes. COF-366 films on hBN substrate present red-shift absorption edge and decreased band gap compared to the bulk COF powders.The organic field-effect transistor device based on COF-366 ultrathin films demonstrates p-type current modulation with an On/Off ratio of 10 5 and mobility of 0.015 cm 2 V -1 s -1 . The present work represents a universal method for COF film growth on dielectric surface, and also provides important insight to the carrier transport of 2D π-conjugated system and potential applications of 2D COFs in electronics.

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Single-Step Solution-Phase Synthesis of Free-Standing Two-Dimensional Polymers and Their Evolution into Hollow Spheres

Cited by 108 publications

References 35 publications

Precision Construction of 2D Heteropore Covalent Organic Frameworks by a Multiple‐Linking‐Site Strategy

Precision Construction of 2D Heteropore Covalent Organic Frameworks by a Multiple‐Linking‐Site Strategy

Acid Exfoliation of Imine‐linked Covalent Organic Frameworks Enables Solution Processing into Crystalline Thin Films

Selective Growth of Covalent Organic Framework Ultrathin Films on Hexagonal Boron Nitride

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