Imagine a climbing frame made of molecules — a rigid scaffold that is almost all empty space, yet strong enough to stand as a crystal. Chemists call these materials metal-organic frameworks, or MOFs, and they are sometimes described as "molecular sponges". In October 2025 the Nobel Prize in Chemistry went to Susumu Kitagawa, Richard Robson and Omar Yaghi for creating them.
Thousands of m² in a single gram
Because a MOF is nearly all pore wall, a few grams can hide an internal surface area comparable to a football pitch. That empty space is what makes MOFs useful.
The chemistry chain
1. Structure
Metal nodes joined by organic linkers into a repeating framework.
2. Property
Mostly empty space, so a huge internal surface area.
3. Behaviour
Gas or water molecules stick to the pore walls (adsorption).
4. Application
Water capture, CO₂ capture, gas storage, separation.
5. Limitation
Cost, stability in moisture and scale-up are still open problems.
Two ingredients, one scaffold
You already know both ingredients. Metal ions carry a positive charge and can attach several partners at once — they become the joints (chemists call them nodes, or secondary building units). Organic linkers are carbon-based molecules with a "hook" at each end — they become the rods. Mix them and they self-assemble into a repeating three-dimensional lattice. Compare that with table salt: also a giant lattice, but packed tight with almost no space inside.
Reticular chemistry: designing the cage
The big idea behind the prize is reticular chemistry: because the joints and rods are predictable, chemists can choose them to design the framework in advance. Change the metal and you change the geometry of the joint; lengthen the linker and you enlarge the cavity — compare the three cages below.
Very large cavity — same scaffold, far more empty space.
Simplified 2D slices through one cage of three frameworks. Same metal nodes, longer organic linker — the cavity grows. Tap a cage to highlight it. Illustrative, not to scale.
Quick check
A chemist keeps the same metal nodes but swaps in a longer organic linker. What happens to the pores?
The three laureates
- Richard Robson — in the late 1980s showed that metal ions and organic molecules could be linked into open, crystalline networks. The idea worked, but early structures were fragile.
- Susumu Kitagawa — showed in the 1990s that such frameworks could take up and release gases, and that some are flexible, breathing in and out without collapsing.
- Omar Yaghi — first used the name "metal–organic framework" in a 1995 Nature paper[3], produced very stable examples such as MOF-5 (1999), and developed the reticular-chemistry approach to designing them.
Timeline
- 1989Robson publishes an open, diamond-like network of copper ions and organic molecules. Promising, but fragile.
- 1992–2003Kitagawa and Yaghi, working separately, make the discoveries the Nobel committee highlights.
- 1995Yaghi names the materials “metal–organic frameworks” in a Nature paper.
- 1997Kitagawa's team shows a framework taking up gases such as methane, nitrogen and oxygen at room temperature.
- 1999Yaghi's MOF-5: very stable, very spacious, still porous when heated to 300 °C.
- 2025Kitagawa, Robson and Yaghi share the Nobel Prize in Chemistry.
Dates from Chemistry World[3] and the Nobel Prize press release[1].
Why did this deserve a Nobel Prize?[1]
- Porous materials already existed (zeolites and activated carbon, for example), but their pores were mostly fixed by nature.
- Robson's early networks were unstable and collapsed easily. Between 1992 and 2003, Kitagawa and Yaghi showed that gases could flow in and out, that frameworks could be flexible, and that a very stable MOF could be modified by rational design.
- The building blocks could now be changed systematically, so chemists could tune pore size and chemistry for a job: gas storage and separation, catalysis, sensing, water capture.
The distinction students often miss
Adsorption is not absorption.
What can you do with empty space?
The Nobel announcement lists water harvesting, carbon dioxide capture, storing toxic gases and catalysis as uses[1]. Their status varies widely, as this table shows.
Water from desert air
MOFs soak up water vapour overnight and release it as liquid when gently warmed by sunlight, even at low humidity. Demonstrated in prototype devices.
Carbon capture
Pores tuned so carbon dioxide sticks while other gases pass through — aimed at flue gas and industrial emissions.
Clean-energy storage
Packing hydrogen or methane into pores at lower pressures than an empty tank would need.
Drug delivery (research)
Drug molecules can be loaded into pores for controlled release; safety depends on the specific framework. Still mainly at the research stage.
| Application | MOF property used | Status (generally) |
|---|---|---|
| Water from desert air | Takes up water vapour at low humidity, releases it when warmed | Prototype devices |
| Carbon capture | Pores tuned to hold CO₂ selectively | Mostly research and pilot scale |
| Hydrogen / methane storage | Huge internal surface holds gas at lower pressure | Research and early development |
| Drug delivery | Drug molecules can be loaded into the pores; safety depends on the specific MOF | Research |
| Removing pollutants such as PFAS | Pores and surface chemistry selectively adsorb them | Research |
Chemistry + AI: can a computer design the next MOF?
Change any joint or rod and you get a different MOF, so there are far more possible frameworks than anyone could make and test by hand. Computing turns that into a pipeline:
- A very large number of possible structures is generated on a computer.
- Simulations, and increasingly machine learning, predict properties such as pore shape and gas uptake.
- The most promising candidates are shortlisted.
- Only those are made and tested in the laboratory.
AI does not replace the laboratory. It reduces the number of candidates that need to be tested, and every prediction still has to be checked by making the material. That is why chemistry, computing and data skills increasingly belong together.
The honest limits
A Nobel Prize recognises the science, not a finished product. Making MOFs cheaply at industrial scale, keeping them stable in moisture, and proving they beat existing materials on cost are all active problems. That gap between a beautiful laboratory result and a practical technology is itself a good exam-style theme: evaluate benefits against limitations.
Exam-style question
Explain why increasing the length of an organic linker can increase the pore size of a MOF. [2 marks]
Show model answer and mark breakdown
- A longer linker holds the metal nodes further apart (1 mark)
- so the cavity (pore) enclosed by the framework is larger (1 mark)
Examiner focus: link cause (longer linker) to a structural consequence (nodes further apart) to the result (larger cavity).
Common mistake: saying 'more atoms means more space' or that the metal ions get bigger. The marks are for the distance between the nodes.
Related reading: PFAS "forever chemicals", a pollution problem MOFs are being researched to help with, and chemical bonds explained.
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Sources and further reading
- NobelPrize.org: Nobel Prize in Chemistry 2025, press release — laureates, prize motivation, what they achieved
- NobelPrize.org: Popular information, Nobel Prize in Chemistry 2025
- Chemistry World: How the pioneers of metal-organic frameworks won the Nobel Prize — dates, and Yaghi's 1995 use of the term
- Chemistry World: Nobel chemistry prize 2025, MOFs
- C&EN: The 2025 chemistry Nobel goes to MOFs
- PNAS: Profile of Robson, Kitagawa and Yaghi
Last reviewed: 26 September 2026. Figures are typical published values and rules can change. Exam wording varies by specification, so check yours.
Frequently asked questions
What is a metal-organic framework (MOF), in one sentence?
A MOF is a crystalline material built from metal ions or small metal clusters joined together by organic molecules acting as linkers, forming a rigid, repeating framework that is mostly empty space.
Why do MOFs have such a huge surface area?
Because the framework is a scaffold rather than a solid block: the metal nodes and organic linkers form the walls of a network of tiny pores and channels, and every wall surface inside those pores counts towards the total. Some MOFs have thousands of square metres of internal surface per gram.
What is reticular chemistry?
Reticular chemistry is the idea of stitching molecular building blocks together with strong bonds into predetermined, repeating networks — so chemists can design the structure rather than hope for it. It is the principle behind MOFs and related materials such as COFs and ZIFs.
Who won the 2025 Nobel Prize in Chemistry for MOFs?
The 2025 Nobel Prize in Chemistry was awarded to Susumu Kitagawa, Richard Robson and Omar Yaghi for the development of metal-organic frameworks.
Is this on the GCSE or A-Level syllabus?
MOFs themselves are not a named topic, but they are a superb application of ideas that are: metal ions, coordination (dative) bonding, giant lattices, surface area and gas adsorption, and carbon capture.
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