The 2025 Nobel Prize in Chemistry was recently awarded to chemists Susumu Kitagawa, Richard Robson, and Omar M. Yaghi for ‘the development of metal-organic frameworks’. This area of chemistry is not new; however, this recent accomplishment could be the recognition these molecules deserve.
Abbreviated as MOFs, these complex compounds form a cage-like shape, with metal atoms joining to one another by carbon-containing linkers. Depending on which metal or linker is used, an empty space is created in the centre of the framework, giving MOFs their unique properties.
Pioneered by chemist Dr. Gérard Férey, the research behind these materials has surged since his death in 2017. Many believe that this recognition should have come earlier, during his career, with the knowledge obtained from his research proving limitless within the field. Férey took a creative approach to the variety of compounds that could be synthesised, clearly proving effective in their study.
Further uses and classifications are continually surfacing from Férey’s research, having completed rigorous analysis to develop and understand MOFs. Additionally, Férey prioritised the training of new researchers, greatly enabling the progression of this inorganic field. Working in a similar timescale to Kitagawa and Yaghi, his work extended beyond the traditional applications of MOFs and into medicinal use.
In order to understand these molecules, I spoke to Dr. Martin Attfield, a reader at the UoM’s Centre for Nanoporous Materials. Dr Attfield is currently researching MOFs – as well as a similar material category, zeolites – by modelling and understanding their molecular properties.
“People often call them a sponge – a crystalline material with lots of pores and spaces of molecular dimensions”. Despite the materials’ complexity, the models built of them are extremely elegant, forming perfect structures similar to those of diamond. MOFs can come in pretty much any combination of linker/metal, opening up hundreds of thousands of possibilities with entirely different structural and physical properties.
Perhaps the most important question about any chemical research is simply: why? The porosity of MOFs can be utilised in sustainability, primarily capturing gas and storing water. Environmental sustainability is one of the biggest issues of scientific research affecting us all in our daily lives, and these molecules could be on the rise to solving some of the more difficult matters.
The empty space, or ‘cavity’, in the centre of the structure is where the usability of MOFs arises. Despite seeming contradictory, storing a gas within the cavity of a network of MOF molecules can take up less space than the gas alone, making storage not just safer but also more economical in terms of space. However, this doesn’t mean that a pollutant will magically disappear. The captured gases must still be disposed of, usually through chemical transformation or safe deposit elsewhere. As a result, the question still remains as to whether they are, in fact, the better option.
More importantly, their ability to hold and capture gases can be utilised to capture CO₂ from entering the atmosphere, keeping pollutants at bay. Gas filtering on a scale as large as the atmosphere is extremely difficult, and while the development of MOFs will not solve that, their use as a preventative measure shows promising steps in the right direction.
Aside from their use for gases, MOFs can be used to harvest water in arid, dry conditions. They are able to harvest water in the cold night air, and release it during the day – a technique that could be lifesaving in desert environments. This technique assumes purification is possible, but yet again appears to be revolutionary in more than one field.
Despite their range of uses now being discovered, chemists have been using MOFs and similar molecules for decades. During my time studying chemistry, I have learnt that the idea of MOFs as organic catalysts is nothing new; however, this is just one of their research applications. Similar classifications, such as zeolites, are currently being studied by Dr. Attfield’s group, which enabled the petrochemical industry in the 1950s and 1960s. This poses the dilemma that many chemists in similar fields face – are the benefits worth the risks associated?
Commercial application of MOFs can be expensive, and some of the metals involved are not very stable. As with most inorganic chemistry, the risk associated with their synthesis and the chemicals required could be bigger than expected. Metal ions and some organic linkers can induce toxicity in certain situations, and large-scale production introduces even more hazards and costs.
MOFs are niche, so it will still take years of research for them to reach our daily lives safely and effectively. It may be that in years to come, we won’t look twice at units containing MOFs that capture CO₂ from machinery, and water harvesting may become a much smaller problem.
For more information about this, visit the Nobel Prize website.
