# Covalent organic frameworks (COFs): structure, linkages and uses

> What COFs are: linkages, 2D stacking and 3D nets, synthesis, characterisation, stability and uses, with COF-1, COF-5, COF-300 and TpPa-1 compared.

URL: https://www.labcanvas.com/cof

Covalent organic frameworks (COFs) are crystalline, porous solids made only of light elements, in which organic building blocks are joined by strong covalent bonds into periodic two- or three-dimensional frameworks (Côté et al. 2005; Diercks and Yaghi 2017). The first two, COF-1 and COF-5, were reported by Yaghi and co-workers in Science in 2005; they are made by reversible condensation reactions, such as boronic acids closing boroxine or boronate ester rings, which let the growing solid correct its errors and crystallise (Côté et al. 2005). Their pores, from about 7 Å to 27 Å in the classic examples, are set by the size and shape of the building blocks.

Covalent organic frameworks (COFs) Published 8 November 2026 Last updated 8 November 2026 12 references

![Covalent organic frameworks: Organic building blocks joined by strong covalent bonds into crystals (B, C, N, O, H)](https://www.labcanvas.com/materials/cof/cof-cover.webp)

**Contents**

**Contents**

- Covalent organic frameworks at a glance
- COF diagram
- COF crystal structure (high-resolution SVG)
- COF in 3D (interactive)
- More COF figures
- What is a covalent organic framework?
- Building blocks, linkages and topology
- 2D COFs: layers, stacking and channels
- 3D COFs and interpenetration
- How COFs are made
- How COFs are characterised
- Stability: from boronate esters to β-ketoenamines
- What COFs are used for
- Four COFs to know
- How to draw a COF
- Four COFs compared
- Related materials
- More on LabCanvas
- Frequently asked questions
- References

## Covalent organic frameworks at a glance

| Definition | Crystalline porous frameworks of organic building blocks joined by strong covalent bonds, made only of light elements (Côté et al. 2005; Diercks and Yaghi 2017) |
| --- | --- |
| First reported | COF-1 and COF-5: Côté, Benin, Ockwig, O’Keeffe, Matzger and Yaghi, Science 310, 1166 (2005) |
| Elements | H, B, C, N and O in the COFs on this site; COF-1 and COF-5 are held together only by bonds between B, C and O (Côté et al. 2005) |
| How they crystallise | Reversible condensation: bonds form and break while the solid grows, so misplaced building blocks can come off again (Côté et al. 2005) |
| Common linkages | Boroxine (COF-1), boronate ester (COF-5), imine (COF-300) and β-ketoenamine (TpPa-1), among others (Geng et al. 2020) |
| 2D COFs | Flat layers, often honeycomb (hcb), stacked about 3.35–3.40 Å apart, eclipsed (AA) or staggered (AB) (from the COF-1 and COF-5 crystal files; Côté et al. 2005) |
| 3D COFs | Tetrahedral building blocks give 3D nets such as ctn (COF-102) and dia (COF-300) (El-Kaderi et al. 2007; Uribe-Romo et al. 2009) |
| Pore sizes | About 7 Å (COF-1), 7.2 Å (COF-300) and 27 Å (COF-5) (Côté et al. 2005; Uribe-Romo et al. 2009) |
| Surface areas | 711 m² g⁻¹ (COF-1), 1,360 m² g⁻¹ (COF-300), 1,590 m² g⁻¹ (COF-5) and 3,472 m² g⁻¹ (3D COF-102) (Côté et al. 2005; Uribe-Romo et al. 2009; El-Kaderi et al. 2007) |
| Thermal stability | Up to 490 °C (COF-300) and 500–600 °C (COF-1, COF-5) (Uribe-Romo et al. 2009; Côté et al. 2005) |
| Chemical stability | Boroxine and boronate ester links are sensitive to water (DeBlase et al. 2013); β-ketoenamine TpPa-1 survives 9 N HCl and boiling water (Kandambeth et al. 2012) |
| Uses studied | Gas storage, carbon capture screening, energy storage, thin films and catalysis (Furukawa and Yaghi 2009; Ongari et al. 2019; DeBlase et al. 2013; Colson et al. 2011; Geng et al. 2020) |

## COF diagram

![COF linkage chemistry figure: boroxine, boronate ester and imine as reversible condensations, and hydrazone, β-ketoenamine and triazine as sturdier linkages, each with its reaction and an example COF](https://www.labcanvas.com/templates/web/cof-linkage-chemistry.webp)

Six COF linkages, from the reversible boroxine, boronate ester and imine condensations that let COFs crystallise to the hydrazone, β-ketoenamine and triazine links that survive water, acid and base. An editable LabCanvas template.

[Edit this figure in LabCanvas](https://www.labcanvas.com/editor.html?template=cof-linkage-chemistry)[See the template](https://www.labcanvas.com/templates/covalent-organic-frameworks/cof-linkages-boroxine-imine-ketoenamine-triazine)

## COF crystal structure (high-resolution SVG)

![Covalent organic frameworks crystal structure drawn from its crystal file](https://www.labcanvas.com/materials/cof/cof-structure.webp)

A real COF from its crystal file: COF-5 (hexagonal, P6/mmm) in the RASPA2 structure library, boronate ester honeycomb layers stacked eclipsed so the 27 Å channels run straight through, seen down c. Drawn by the LabCanvas figure editor; open it to change the style, cells and view.

[Edit the structure in LabCanvas](https://www.labcanvas.com/editor.html?crystal=sample:cof-5)[Download SVG](https://www.labcanvas.com/materials/cof/cof-structure.svg)[Download PNG (3000 px)](https://www.labcanvas.com/materials/cof/cof-structure.png)

## COF in 3D (interactive)

![Covalent organic frameworks 3D model](https://www.labcanvas.com/gallery3d/cof3d.webp)

Loading the 3D model…

A COF in 3D: COF-5, boronate ester layers stacked eclipsed (AA), with the 2.7 nm hexagonal channels shown and the linkages highlighted. Drag to turn it.

[Open in the 3D Studio](https://www.labcanvas.com/studio3d.html?add=cof3d)

## More COF figures

![Characterizing a 2D COF figure: powder XRD compared with eclipsed and staggered models, an N₂ isotherm at 77 K, a pore size distribution near 2.7 nm, FTIR of monomers and COF, solid-state ¹³C NMR and a thermogravimetric curve](https://www.labcanvas.com/templates/web/cof-characterization-pxrd-ftir-nmr.webp)

The four checks for a new COF: which stacking (PXRD against eclipsed and staggered models), how porous (N₂ at 77 K and pore size), which bonds (FTIR and solid-state ¹³C NMR) and how stable (thermogravimetry). An editable LabCanvas template.

[Edit this figure in LabCanvas](https://www.labcanvas.com/editor.html?template=cof-characterization-pxrd-ftir-nmr)[See the template](https://www.labcanvas.com/templates/covalent-organic-frameworks/cof-characterization-pxrd-ftir-nmr)

## What is a covalent organic framework?

A covalent organic framework is an organic polymer that is also a crystal. Small, rigid molecules with two, three or four reactive groups are joined end to end by covalent bonds, and because the building blocks have fixed shapes and fixed angles between their reactive groups, the result is a regular, open network rather than a tangle. The pores of that network are permanent: they stay open when the solvent is removed, so a COF has a measurable surface area like a zeolite or a metal–organic framework (Côté et al. 2005).

Until 2005, organic polymers made of strong covalent bonds were amorphous, because a bond formed in the wrong place stayed there. Côté, Yaghi and co-workers showed that this changes when the bond-forming reaction is **reversible**: in COF-1 and COF-5, boronic acids condense into B–O rings while the solid grows, and misplaced building blocks can come off again, so the product is crystalline and permanently porous, “entirely held by strong bonds between B, C, and O atoms” (Côté et al. 2005). The idea extended reticular chemistry, the design of frameworks from building blocks and nets, from metal–organic frameworks to purely organic ones (Diercks and Yaghi 2017).

COFs are made only of light elements. Compared with [metal–organic frameworks](https://www.labcanvas.com/mof), which join metal ions or clusters with organic linkers through coordination bonds, they have no metal in the backbone and their links are covalent B–O, C=N or C–N bonds (Diercks and Yaghi 2017; Feng et al. 2012).

## Building blocks, linkages and topology

A COF is described by three choices: the **building blocks** (their shape and number of reactive groups), the **linkage** that forms between them, and the **net** (topology) that the building blocks are assembled on.

The linkage sets how a COF is made and what it survives. The first COFs used boron chemistry. In [COF-1](https://www.labcanvas.com/cof/cof-1), three boronic acids of benzene-1,4-diboronic acid (BDBA) close a flat six-membered boroxine ring, releasing three water molecules:

$$\ce{3 R-B(OH)2 -> (R-BO)3 + 3 H2O}$$

In [COF-5](https://www.labcanvas.com/cof/cof-5), each boronic acid of BDBA instead condenses with a catechol pair of hexahydroxytriphenylene (HHTP) into a five-membered boronate ester ring (Côté et al. 2005). [COF-300](https://www.labcanvas.com/cof/cof-300) brought nitrogen chemistry: amines and aldehydes condense into imine bonds, again with loss of water (Uribe-Romo et al. 2009),

$$\ce{R-CHO + H2N-R'} \rightleftharpoons \ce{R-CH=N-R' + H2O}$$

and in [TpPa-1](https://www.labcanvas.com/cof/tppa-1) the imine formed from 1,3,5-triformylphloroglucinol (Tp) tautomerises irreversibly to a β-ketoenamine, so no hydrolysable imine bond remains (Kandambeth et al. 2012). Many other linkages have since been used, including hydrazones, azines and triazines (Geng et al. 2020).

The geometry of the building blocks decides the net. A triangular node and a linear linker give a **honeycomb (hcb)** layer: HHTP at the corners and BDBA along the edges in COF-5, Tp at the corners and p-phenylenediamine along the edges in TpPa-1. In COF-1 the boroxine rings themselves are the triangular nodes. A tetrahedral node gives a 3D net instead: tetrahedral boronic acids gave the 3D COF-102 (ctn net) and COF-103 (El-Kaderi et al. 2007), and tetrahedral tetra-(4-anilyl)methane with linear terephthaldehyde gave the diamond (dia) net of COF-300 (Uribe-Romo et al. 2009).

## 2D COFs: layers, stacking and channels

Most COFs are two-dimensional: flat covalent sheets that stack on top of one another, held together by weaker interactions between the layers. How they stack decides the pores. In COF-5 the layers sit directly over one another, **eclipsed (AA)**, in space group P6/mmm, so the hexagons line up into open one-dimensional channels 27 Å across (Côté et al. 2005). In COF-1 each layer is shifted over the pores of the next, **staggered (AB)**, in P6₃/mmc, which narrows the open pore to about 7 Å (Côté et al. 2005).

The layers are close together: about 3.40 Å apart in COF-5 and about 3.35 Å in COF-1, from their crystal files, close to the spacing of graphite. The stacking cannot usually be seen directly in a powder. It is assigned by comparing the measured powder X-ray diffraction pattern with patterns calculated for eclipsed and staggered models, which is how COF-1 and COF-5 were assigned (Côté et al. 2005).

Because the pore follows from the building blocks, a longer linker or a larger node gives a larger channel. The jump from COF-1 to COF-5, about 7 Å to 27 Å, came from a larger node (HHTP) and eclipsed stacking (Côté et al. 2005), and the hexagonal boronate ester layer of COF-5 became a template for many later 2D COFs with longer linkers.

## 3D COFs and interpenetration

Three-dimensional COFs are held together by covalent bonds in every direction. The first, COF-102 and COF-103, were made in 2007 from tetrahedral building blocks and boroxine links; COF-102 reached a surface area of 3,472 m² g⁻¹ (El-Kaderi et al. 2007), more than twice that of COF-5.

COF-300 was the first 3D COF joined by imine bonds. It has the diamond (dia) topology, every tetrahedral carbon joined to four others, and its open diamond nets grow through one another: **five interwoven nets** fill the space, yet it keeps pores 7.2 Å across, a surface area of 1,360 m² g⁻¹ and thermal stability to 490 °C (Uribe-Romo et al. 2009). Interpenetration like this is common in open 3D nets and shrinks the pores, so it is something to check for in any new 3D COF. COF-300 later became one of the first COFs grown as large single crystals and solved by single-crystal X-ray diffraction, which showed the degree of interpenetration and how water guests sit in the pores (Ma et al. 2018).

## How COFs are made

Most COFs are made by **solvothermal synthesis**: the building blocks are heated together in a solvent mixture in a sealed tube, and the framework precipitates as a crystalline powder (Côté et al. 2005). For COF-1, BDBA is suspended in mesitylene and dioxane in a sealed Pyrex tube and heated (Côté et al. 2005); for TpPa-1, Tp and p-phenylenediamine react in 1:1 mesitylene/dioxane (Kandambeth et al. 2012).

- **Reversible bond formation.** The condensation releases water, and the bonds can break again while the solid grows. This error correction is what makes the product crystalline rather than amorphous (Côté et al. 2005; Uribe-Romo et al. 2009).
- **Locking in (optional).** TpPa-1 combines a reversible Schiff base step, which gives crystallinity, with an irreversible tautomerism to the β-ketoenamine, which gives stability (Kandambeth et al. 2012).
- **Washing and activation.** The powder is washed and the solvent in the pores removed, for example the mesitylene held in COF-1, before surface area and gas uptake are measured. Boron-linked COFs are then kept dry (Côté et al. 2005; DeBlase et al. 2013).

COFs can also be grown as films: boronate ester COFs from HHTP have been grown as oriented thin films on single-layer [graphene](https://www.labcanvas.com/2d-materials/graphene), with better crystallinity than the powders (Colson et al. 2011).

## How COFs are characterised

A new COF has to be shown to be crystalline, porous, linked by the intended bond and stable. The standard checks are:

- **Powder X-ray diffraction (XRD).** The measured pattern is compared with patterns calculated for candidate structures, such as eclipsed and staggered stacks, to assign the structure (Côté et al. 2005). Large single crystals, where they can be grown, give the structure directly (Ma et al. 2018).
- **Gas sorption (BET).** Nitrogen isotherms give the surface area and pore size; COF-5, with its 27 Å channels, is mesoporous (Côté et al. 2005).
- **Infrared and solid-state NMR (FTIR, NMR).** These show that the linkage has formed and the starting groups have gone; in TpPa-1 they show the keto-enamine form, not the enol-imine (Kandambeth et al. 2012).
- **Thermal and chemical stability (TGA, soaking tests).** Thermogravimetry gives the decomposition temperature, 500–600 °C for COF-1 and COF-5 (Côté et al. 2005); soaking in acid, base or boiling water followed by powder XRD shows whether the framework survives (Kandambeth et al. 2012).

## Stability: from boronate esters to β-ketoenamines

COFs are thermally robust: COF-1 and COF-5 are stable to 500–600 °C and COF-300 to 490 °C (Côté et al. 2005; Uribe-Romo et al. 2009). Their weak point is chemical. The reversibility that lets a COF crystallise also lets its bonds come apart: boroxine and boronate ester links are sensitive to water (DeBlase et al. 2013), so COF-1 and COF-5 are stored and handled dry, and imine COFs can be hydrolysed.

TpPa-1 showed a way out. Its imine links tautomerise irreversibly to β-ketoenamines, which leaves no imine for water or acid to attack; TpPa-1 stays crystalline after 9 N hydrochloric acid and boiling water, and its 2,5-dimethyl analogue TpPa-2 also survives 9 N sodium hydroxide (Kandambeth et al. 2012). DeBlase et al. (2013) used the same chemistry to make a redox-active β-ketoenamine COF that works in a strongly acidic electrolyte.

## What COFs are used for

- **Gas storage.** COFs are light and porous. At 35 bar, COF-5 takes up 36 mg g⁻¹ of hydrogen at 77 K and 779 mg g⁻¹ of CO₂ at 298 K, against 15 and 210 mg g⁻¹ for COF-1, and the 3D COF-102 takes up more than either (Furukawa and Yaghi 2009).
- **Carbon capture screening.** The CURATED COFs database collects optimised COF structures, including TpPa-1 and COF-300, and uses them to compute CO₂ and N₂ adsorption for carbon capture (Ongari et al. 2019).
- **Energy storage.** A redox-active β-ketoenamine COF electrode kept a higher capacitance than a non-redox-active COF after 5,000 charge–discharge cycles in acidic electrolyte (DeBlase et al. 2013).
- **Thin films and electronics.** Oriented boronate ester COF films grown on graphene (Colson et al. 2011).
- **Catalysis, separations and more.** Chemically stable COFs such as the β-ketoenamines are studied for catalysis, separations and optoelectronics, among other uses reviewed by Geng et al. (2020).

## Four COFs to know

- [COF-1](https://www.labcanvas.com/cof/cof-1): the first COF, BDBA condensed into boroxine (B₃O₃) rings; staggered honeycomb layers, pores of about 7 Å, 711 m² g⁻¹ (Côté et al. 2005).
- [COF-5](https://www.labcanvas.com/cof/cof-5): boronate ester layers of HHTP and BDBA stacked eclipsed into 27 Å channels, 1,590 m² g⁻¹; the standard picture of a 2D COF (Côté et al. 2005).
- [COF-300](https://www.labcanvas.com/cof/cof-300): the first imine-linked 3D COF, five interwoven diamond nets with 7.2 Å pores, 1,360 m² g⁻¹ (Uribe-Romo et al. 2009).
- [TpPa-1](https://www.labcanvas.com/cof/tppa-1): a β-ketoenamine COF of Tp and p-phenylenediamine that survives 9 N HCl and boiling water (Kandambeth et al. 2012).

## How to draw a COF

For a paper, slide or poster, show a COF at three levels: the building blocks and the linkage they form, one layer or net, and the stack or crystal with a pore marked. The linkage figure above has the six common linkages side by side and opens as an editable LabCanvas figure; the characterisation figure has the PXRD, sorption, FTIR, NMR and TGA panels for a methods figure. The crystal structure drawing is a high-resolution SVG of COF-5 from its crystal file, and the LabCanvas figure editor’s Library has the other COF crystal files and the CURATED COFs database, where you can change the style, the number of cells and the view. The 3D model opens in the LabCanvas 3D Studio, where you can change the number of layers, show the channels and export a high-resolution image.

## Four COFs compared

| COF | Dimension and net | Linkage | Building blocks | Stacking or packing | Pore size | Surface area | Stability | First report |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| COF-1 | 2D, hcb | Boroxine (B₃O₃) | BDBA alone | Staggered (AB), P6₃/mmc | About 7 Å | 711 m² g⁻¹ | To 500–600 °C; water-sensitive | Côté et al., Science 2005 |
| COF-5 | 2D, hcb | Boronate ester | HHTP + BDBA | Eclipsed (AA), P6/mmm | 27 Å channels | 1,590 m² g⁻¹ | To 500–600 °C; water-sensitive | Côté et al., Science 2005 |
| COF-300 | 3D, dia | Imine (C=N) | Tetra-(4-anilyl)methane + terephthaldehyde | Five interwoven diamond nets | 7.2 Å | 1,360 m² g⁻¹ | To 490 °C | Uribe-Romo et al., JACS 2009 |
| TpPa-1 | 2D, hcb | β-Ketoenamine | Tp + p-phenylenediamine | Layers 3.4 Å apart (CURATED file) | — | — | Crystalline after 9 N HCl and boiling water | Kandambeth et al., JACS 2012 |

## Related materials

[![COF-1: Boroxine-linked layers, staggered stacking (C₃H₂BO)](https://www.labcanvas.com/materials/cof-1/cof-1-cover.webp) COF C₃H₂BO COF-1 COF-1, the first covalent organic framework: boroxine-linked layers from one boronic acid, staggered stacking, 711 m² g⁻¹, synthesis and stability, cited.](https://www.labcanvas.com/cof/cof-1)

[![COF-5: Boronate ester layers, eclipsed hexagonal pores (C₉H₄BO₂)](https://www.labcanvas.com/materials/cof-5/cof-5-cover.webp) COF C₉H₄BO₂ COF-5 COF-5, the boronate ester COF from HHTP and BDBA: eclipsed layers, 27 Å channels, 1,590 m² g⁻¹, synthesis and stability, with 2D and 3D figures to edit.](https://www.labcanvas.com/cof/cof-5)

[![COF-300: Imine-linked diamond nets, five interwoven ((C₄₁H₂₈N₄)ₙ)](https://www.labcanvas.com/materials/cof-300/cof-300-cover.webp) COF (C₄₁H₂₈N₄)ₙ COF-300 COF-300, the first imine-linked 3D COF: five interwoven diamond nets, 7.2 Å pores, 1,360 m² g⁻¹, stable to 490 °C. Structure, synthesis and papers.](https://www.labcanvas.com/cof/cof-300)

[![TpPa-1: β-Ketoenamine COF that survives acid and water ((C₁₈H₁₂N₃O₃)ₙ)](https://www.labcanvas.com/materials/tppa-1/tppa-1-cover.webp) COF (C₁₈H₁₂N₃O₃)ₙ TpPa-1 TpPa-1, the β-ketoenamine COF from Tp and p-phenylenediamine: why it survives acid and boiling water, its structure, synthesis and surface area, cited.](https://www.labcanvas.com/cof/tppa-1)

## More on LabCanvas

- [COF linkages: from reversible to robust](https://www.labcanvas.com/templates/covalent-organic-frameworks/cof-linkages-boroxine-imine-ketoenamine-triazine): Editable figure template
- [Characterizing a 2D COF](https://www.labcanvas.com/templates/covalent-organic-frameworks/cof-characterization-pxrd-ftir-nmr): Editable figure template
- [More COF figure templates](https://www.labcanvas.com/templates/covalent-organic-frameworks): Ready-made, cited figures to edit
- [Characterisation techniques explained](https://www.labcanvas.com/techniques): XRD, XPS, BET, SEM, TEM, NMR, FTIR, Raman and more
- [Crystal structure figure software compared](https://www.labcanvas.com/blog/crystal-structure-visualization-software): VESTA, Mercury, CrystalMaker, Avogadro and LabCanvas
- [XRD Scherrer crystallite size calculator](https://www.labcanvas.com/tools/xrd-scherrer-calculator): Free tool
- [Molar mass calculator](https://www.labcanvas.com/tools/molar-mass-calculator): Free tool
- [Journal figure size guide](https://www.labcanvas.com/blog/journal-figure-size-guide): Column widths and resolutions for 38 journals
- [3D models gallery](https://www.labcanvas.com/gallery): Turn MOFs, COFs, perovskites and more in 3D

## Frequently asked questions

### What is a covalent organic framework (COF)?

A crystalline, porous solid in which organic building blocks made of light elements are joined by strong covalent bonds into a periodic 2D or 3D framework. The first COFs, COF-1 and COF-5, were reported by Yaghi and co-workers in Science in 2005 (Côté et al. 2005).

### What is the difference between a COF and a MOF?

A metal–organic framework joins metal ions or clusters with organic linkers through coordination bonds; a COF has no metal in its backbone and joins organic building blocks through covalent bonds such as B–O, C=N or C–N. Both are designed from building blocks and nets (reticular chemistry) and both are permanently porous (Diercks and Yaghi 2017).

### How can a covalent polymer be crystalline?

By using reversible reactions. In COF synthesis the bonds form and break while the solid grows, so building blocks that join in the wrong place can come off again and the framework crystallises instead of staying amorphous (Côté et al. 2005).

### What linkages are used in COFs?

The first COFs used boroxine (COF-1) and boronate ester (COF-5) links; COF-300 introduced imines and TpPa-1 β-ketoenamines. Hydrazones, azines, triazines and other linkages are also used (Côté et al. 2005; Uribe-Romo et al. 2009; Kandambeth et al. 2012; Geng et al. 2020).

### What is the difference between eclipsed and staggered COFs?

In an eclipsed (AA) 2D COF the layers lie directly over one another, so the pores line up into open channels, 27 Å across in COF-5. In a staggered (AB) COF each layer is shifted over the pores of the next, which narrows the open pore, to about 7 Å in COF-1. The stacking is assigned by comparing powder XRD with calculated patterns (Côté et al. 2005).

### What is the pore size and surface area of COFs?

It depends on the building blocks: COF-1 has pores of about 7 Å and 711 m²/g, COF-5 27 Å channels and 1,590 m²/g, COF-300 7.2 Å pores and 1,360 m²/g, and the 3D COF-102 reaches 3,472 m²/g (Côté et al. 2005; Uribe-Romo et al. 2009; El-Kaderi et al. 2007).

### Are COFs stable in water?

Boroxine and boronate ester COFs are sensitive to water, and imine COFs can be hydrolysed. β-Ketoenamine COFs such as TpPa-1 are much more robust: TpPa-1 stays crystalline in 9 N hydrochloric acid and boiling water (DeBlase et al. 2013; Kandambeth et al. 2012).

### How are COFs made?

Usually solvothermally: the building blocks are heated in a solvent mixture such as mesitylene and dioxane in a sealed tube, and the crystalline framework precipitates. It is then washed and activated by removing the solvent from its pores (Côté et al. 2005; Kandambeth et al. 2012).

### What are COFs used for?

They are studied for gas storage (hydrogen, methane, CO₂), carbon capture, energy storage electrodes, thin films for electronics, catalysis and separations (Furukawa and Yaghi 2009; Ongari et al. 2019; DeBlase et al. 2013; Colson et al. 2011; Geng et al. 2020).

## References

- A. P. Côté, A. I. Benin, N. W. Ockwig, M. O’Keeffe, A. J. Matzger, O. M. Yaghi. Porous, crystalline, covalent organic frameworks. *Science* 2005, 310, 1166–1170. [doi:10.1126/science.1120411](https://doi.org/10.1126/science.1120411)
- C. S. Diercks, O. M. Yaghi. The atom, the molecule, and the covalent organic framework. *Science* 2017, 355, eaal1585. [doi:10.1126/science.aal1585](https://doi.org/10.1126/science.aal1585)
- X. Feng, X. Ding, D. Jiang. Covalent organic frameworks. *Chem. Soc. Rev.* 2012, 41, 6010–6022. [doi:10.1039/C2CS35157A](https://doi.org/10.1039/C2CS35157A)
- K. Geng et al.. Covalent organic frameworks: design, synthesis, and functions. *Chem. Rev.* 2020, 120, 8814–8933. [doi:10.1021/acs.chemrev.9b00550](https://doi.org/10.1021/acs.chemrev.9b00550)
- H. M. El-Kaderi et al.. Designed synthesis of 3D covalent organic frameworks. *Science* 2007, 316, 268–272. [doi:10.1126/science.1139915](https://doi.org/10.1126/science.1139915)
- F. J. Uribe-Romo, J. R. Hunt, H. Furukawa, C. Klöck, M. O’Keeffe, O. M. Yaghi. A crystalline imine-linked 3-D porous covalent organic framework. *J. Am. Chem. Soc.* 2009, 131, 4570–4571. [doi:10.1021/ja8096256](https://doi.org/10.1021/ja8096256)
- T. Ma et al.. Single-crystal x-ray diffraction structures of covalent organic frameworks. *Science* 2018, 361, 48–52. [doi:10.1126/science.aat7679](https://doi.org/10.1126/science.aat7679)
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**Contents**

- Covalent organic frameworks at a glance
- COF diagram
- COF crystal structure (high-resolution SVG)
- COF in 3D (interactive)
- More COF figures
- What is a covalent organic framework?
- Building blocks, linkages and topology
- 2D COFs: layers, stacking and channels
- 3D COFs and interpenetration
- How COFs are made
- How COFs are characterised
- Stability: from boronate esters to β-ketoenamines
- What COFs are used for
- Four COFs to know
- How to draw a COF
- Four COFs compared
- Related materials
- More on LabCanvas
- Frequently asked questions
- References