Opportunities of Covalent Organic Frameworks for Advanced Applications

Advanced Science, Journal Year: 2018, Volume and Issue: 6(2)

Published: Nov. 12, 2018

Abstract Covalent organic frameworks (COFs) are an emerging class of functional nanostructures with intriguing properties, due to their unprecedented combination high crystallinity, tunable pore size, large surface area, and unique molecular architecture. The range properties characterized in COFs has rapidly expanded include those interest for numerous applications ranging from energy environment. Here, a background overview is provided, consisting brief introduction porous materials the design feature COFs. Then, recent advancements as designer platform plethora emphasized together discussions about strategies principles involved. Finally, challenges remaining this type material real outlined.

Language: Английский

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New synthetic strategies toward covalent organic frameworks

Chemical Society Reviews, Journal Year: 2020, Volume and Issue: 49(10), P. 2852 - 2868

Published: Jan. 1, 2020

This tutorial review highlights the representative advances in new synthetic strategies toward covalent organic frameworks.

Language: Английский

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Covalent Organic Frameworks: Chemical Approaches to Designer Structures and Built‐In Functions

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 59(13), P. 5050 - 5091

Published: May 30, 2019

Abstract A new approach has been developed to design organic polymers using topology diagrams. This strategy enables covalent integration of units into ordered topologies and creates a polymer form, that is, frameworks. is breakthrough in chemistry because it sets molecular platform for synthesizing with predesignable primary high‐order structures, which central aim over century but unattainable traditional principles. field its own features are distinct from conventional polymers. Review summarizes the fundamentals as well major progress by focusing on used including principles, synthetic strategies, control methods. We scrutinize built‐in functions specific structures revealing various interplays mechanisms involved expression function. propose fundamental issues be addressed future directions physics, materials, application perspectives.

Language: Английский

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Photocatalytic Molecular Oxygen Activation by Regulating Excitonic Effects in Covalent Organic Frameworks

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(49), P. 20763 - 20771

Published: Nov. 23, 2020

Excitonic effects caused by Coulomb interactions between electrons and holes play subtle significant roles on photocatalysis, yet have been long ignored. Herein, porphyrinic covalent organic frameworks (COFs, specifically DhaTph-M), in the absence or presence of different metals porphyrin centers, shown as ideal models to regulate excitonic effects. Remarkably, incorporation Zn2+ COF facilitates conversion singlet triplet excitons, whereas Ni2+ introduction promotes dissociation excitons hot carriers under photoexcitation. Accordingly, discriminative behavior DhaTph-Zn DhaTph-Ni enables activation O2 1O2 O2•–, respectively, visible light irradiation, resulting distinctly activity selectivity photocatalytic terpinene oxidation. Benefiting from these results, exhibits excellent O2•–-engaged hydroxylation boronic acid, while possesses superior performance 1O2-mediated selective oxidation sulfides. This work provides in-depth insights into molecular oxygen opens an avenue regulation based COFs.

Language: Английский

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Regulating Photocatalysis by Spin-State Manipulation of Cobalt in Covalent Organic Frameworks

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(39), P. 16723 - 16731

Published: Sept. 7, 2020

While catalysis is highly dependent on the electronic structure of catalyst, understanding catalytic performance affected by electron spin regulation remains challenging and rare. Herein, we have developed a facile strategy to manipulation cobalt state over covalent organic frameworks (COFs), COF-367-Co, simply changing oxidation Co centered in porphyrin. Density functional theory (DFT) calculations together with experimental results confirm that CoII CoIII are embedded COF-367 S = 1/2 0 ground states, respectively. Remarkably, photocatalytic CO2 reduction indicate COF-367-CoIII exhibits favorable activity significantly enhanced selectivity HCOOH, accordingly much reduced CO CH4, sharp contrast COF-367-CoII. The highlight spin-state transition greatly regulates performance. Theoretical further disclose presence COF-367-Co preferable formation HCOOH but detrimental its conversion, which clearly accounts for distinctly different photocatalysis To best our knowledge, this first report regulating COFs.

Language: Английский

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Semiconducting 2D Triazine-Cored Covalent Organic Frameworks with Unsubstituted Olefin Linkages

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(36), P. 14272 - 14279

Published: Aug. 20, 2019

Establishing an sp2-carbon-bonding pattern is one of the efficient accesses to various organic semiconducting materials. However, less-reversible carbon-carbon bond formation makes it still challenging spatially construct a well-defined framework with π-extended two-dimensional (2D) structure through solution process. Here, Knoevenagel condensation approach synthesize two new 2D covalent frameworks (COFs) connected by unsubstituted double linkages activating methyl carbons 2,4,6-trimethyl-1,3,5-triazine monomer presented. The resulting sp2-carbon-linked triazine-cored sheets are vertically stacked into high-crystalline honeycomb-like structures, endowing this kind COF extended π-delocalization, tunable energy levels, as well high surface areas, regular open channels, and chemical stabilities. On other hand, their microfibrillar morphologies allow for facile manipulation thin films photoelectrodes without additive. Accordingly, such kinds COF-based exhibit photocurrents up ∼45 μA cm-2 at 0.2 V vs RHE rapid charge transfer rates, in comparison imine-linked photoelectrodes. In addition, both COFs applicable conducting photocatalytic hydrogen generation from water splitting visible-light irradiation.

Language: Английский

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Facile transformation of imine covalent organic frameworks into ultrastable crystalline porous aromatic frameworks

Nature Communications, Journal Year: 2018, Volume and Issue: 9(1)

Published: July 25, 2018

The growing interest in two-dimensional imine-based covalent organic frameworks (COFs) is inspired by their crystalline porous structures and the potential for extensive π-electron delocalization. intrinsic reversibility strong polarization of imine linkages, however, leads to insufficient chemical stability optoelectronic properties. Developing COFs with improved robustness π-delocalization highly desirable but remains an unsettled challenge. Here we report a facile strategy that transforms imine-linked into ultrastable aromatic kinetically fixing reversible linkage via aza-Diels-Alder cycloaddition reaction. as-formed, quinoline-linked not only retain crystallinity porosity, also display dramatically enhanced over COF precursors, rendering them among most robust up-to-date can withstand acidic, basic redox environment. Owing diversity reaction structural tunability COFs, pores be readily engineered realize pre-designed surface functionality.

Language: Английский

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Rational design of isostructural 2D porphyrin-based covalent organic frameworks for tunable photocatalytic hydrogen evolution

Nature Communications, Journal Year: 2021, Volume and Issue: 12(1)

Published: March 1, 2021

Abstract Covalent organic frameworks have recently gained increasing attention in photocatalytic hydrogen generation from water. However, their structure-property-activity relationship, which should be beneficial for the structural design, is still far-away explored. Herein, we report designed synthesis of four isostructural porphyrinic two-dimensional covalent (MPor-DETH-COF, M = H 2 , Co, Ni, Zn) and activity generation. Our results clearly show that all adopt AA stacking structures, with high crystallinity large surface area. Interestingly, incorporation different transition metals into porphyrin rings can rationally tune evolution rate corresponding frameworks, order CoPor-DETH-COF < Por-DETH-COF NiPor-DETH-COF ZnPor-DETH-COF. Based on detailed experiments calculations, this tunable performance mainly explained by tailored charge-carrier dynamics via molecular engineering. This study not only represents a simple effective way efficient tuning activities at level, but also provides valuable insight structure design better photocatalysis.

Language: Английский

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Two-dimensional covalent organic frameworks with hierarchical porosity

Chemical Society Reviews, Journal Year: 2020, Volume and Issue: 49(12), P. 3920 - 3951

Published: Jan. 1, 2020

This review highlights the state-of-the-art progress achieved in two-dimensional covalent organic frameworks (COFs) with hierarchical porosity, an emerging class of COFs constructed by integrating different types pores into one framework.

Language: Английский

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Porous Crystalline Olefin-Linked Covalent Organic Frameworks

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(17), P. 6848 - 6852

Published: April 19, 2019

The first unsubstituted olefin-linked covalent organic framework, termed COF-701, was made by linking 2,4,6-trimethyl-1,3,5-triazine (TMT) and 4,4′-biphenyldicarbaldehyde (BPDA) through Aldol condensation. Formation of the olefin (-CH═CH-) linkage upon reticulation is confirmed Fourier transform infrared (FT-IR) spectroscopy solid-state 13C cross-polarization magic angle spinning (CP-MAS) NMR framework its 13C-isotope-labeled analogue. COF-701 found to be porous (1715 m2 g–1) retain composition crystallinity under both strongly acidic basic conditions. high chemical robustness attributed linkages. Immobilization strong Lewis acid BF3·OEt2 in pores structure yields BF3⊂COF-701. In material, catalytic activity guest retained, as evidenced a benchmark Diels–Alder reaction.

Language: Английский

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