Dataset Information

Facile fabrication of hollow tubular covalent organic frameworks using decomposable monomer as building block.

ABSTRACT: In this study, a commercial and low-toxicity hydrazide-containing building block has been used to construct azine-linked covalent organic frameworks (COFs). New style COFs were constructed between flexible formic hydrazide (FH) and 1,3,5-triformylphloroglucinal (Tp) or 1,3,5-triformylbenzene (TFB). The two resulting COFs (TpFH and TFBFH) exhibited uniform hollow tubular morphology (20-50 nm for TpFH, 50-100 nm for TFBFH). Compared to hydrazine, FH has low-toxicity and is a flexible monomer, consisting of amine and aldehyde groups. The decomposition of FH slows down the reaction rate and the as-synthesized FH-series COFs (708 m² g^-1 for TpFH and 888 m² g^-1 for TFBFH) had higher specific surface area than hydrazine-series COFs (617 m² g^-1 for TpAzine and 472 m² g^-1 for TFBAzine). A detailed time-dependent investigation was carried out to interpret the mechanism of hollow structure formation, and Ostwald ripening possibly happens during the formation of hollow COF microstructures. Considering the porous and high density N, O elements of these materials, preliminary applications of the metal ions removal from aqueous solution and gas storage were implemented.

SUBMITTER: Li Y

PROVIDER: S-EPMC9034008 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature

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Facile fabrication of hollow tubular covalent organic frameworks using decomposable monomer as building block.

Li Ya Y Wang Chang C Ma Shujuan S Xu Junwen J Li Xiaowei X Wei Yinmao Y Ou Junjie J

RSC advances 20210614 34

In this study, a commercial and low-toxicity hydrazide-containing building block has been used to construct azine-linked covalent organic frameworks (COFs). New style COFs were constructed between flexible formic hydrazide (FH) and 1,3,5-triformylphloroglucinal (Tp) or 1,3,5-triformylbenzene (TFB). The two resulting COFs (TpFH and TFBFH) exhibited uniform hollow tubular morphology (20-50 nm for TpFH, 50-100 nm for TFBFH). Compared to hydrazine, FH has low-toxicity and is a flexible monomer, cons ...[more]

PMID: 35479390

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Project description:Covalent organic frameworks (COFs) are a class of crystalline porous materials distinctively built solely from organic elements, carbon, oxygen, hydrogen, and often nitrogen or boron. They form light, mechanically rigid, and chemically stable networks that have many advantages, but their low solubility and poor processability create issues with developing large-scale films or membranes. Two-dimensional (2D) COFs possess periodic porous crystallinity, functionality, modularity, and layered one-dimensional (1D) transport channels. All of these traits, along with the semiconducting properties of selected COFs, make them interesting candidates for integration in optoelectronic devices. Therefore, it is still a challenge to explore computationally and structurally the semiconductivity of COFs and to determine their final potential. Herein, we report on the possible semiconducting properties and results of polyimide-COF materials using density functional theory calculations. Our analysis includes monolayers and multilayers (AA- and AB-stacked modes) of mellitic triimide frameworks designed from mellitic trianhydride (MTA) as the main building knot, including MTI-TAPB-COF, which was previously synthesized from the condensation reaction of MTA and 1,3,5-tris(4-aminophenyl)benzene (TAPB), and other previously unreported structures based on MTA. Respective frameworks have been selected due to the difference in building block symmetry (C3 + C2 and C3 + C3) and different chemical linkages, either by benzene or by pyridine rings. We find the polyimide multilayers to be stable and with varying electronic properties. The finite band gap exhibited by every structure (monolayer and stacked) was sensitive to atomic arrangement. Stacking introduces dispersion to an otherwise flat band structure of the materials, which appeared to be highly sensitive to stacking direction. The effect of stacking was similar for each COF, but the magnitude of band structure change was different and dependent on the symmetry of the building blocks.

Project description:We describe why the cyclic heteropolyanion [P8W48O184]40- (abbreviated as {P8W48}) is an ideal building block for the construction of intrinsically porous framework materials by classifying and analyzing >30 coordination polymers incorporating this polyoxometalate (POM) ligand. This analysis shows that the exocyclic coordination of first-row transition metals (TMs) to {P8W48} typically yields frameworks which extend through {W-O-TM-O-W} bridges in one, two, or three dimensions. However, despite the rich structural diversity of such compounds, the coordination of TMs to the {P8W48} ring is poorly understood, and therefore largely unpredictable, and had not until now been present with any structural classification that could allow rational design. Herein, not only do we present a new approach to understand and classify this new class of materials, we also present three {P8W48}-based frameworks which complement those frameworks which have previously been described. These new compounds help us postulate a new taxonomy of these materials. This is possible because the TM coordination sites of the {P8W48} ring are found, once fully mapped, to lead to well-defined classes of connectivity. Together, analysis provides insight into the nature of the building block connectivity within each framework, to facilitate comparisons between related structures, and to fundamentally unite this family of compounds. Hence we have tentatively named these compounds as "POMzites" to reflect the POM-based composition and zeolitic nature of each family member, although crucially, POMzites differ from zeolites in the modular manner of their preparation. As the synthesis of further POMzites is anticipated, the classification system and terminology introduced here will allow new compounds to be categorized and understood in the context of the established materials. A better understanding of TM coordination to the {P8W48} ring may allow the targeted synthesis of new frameworks rather than the reliance on serendipity apparent in current methods.

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Facile fabrication of hollow tubular covalent organic frameworks using decomposable monomer as building block.

Publications

Facile fabrication of hollow tubular covalent organic frameworks using decomposable monomer as building block.

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