Who won the Nobel Prize in Chemistry 2025?
Metal-organic frameworks, a near boundless group of functional materials that faced years of apathy, are the focal point of this year’s prize.
The Nobel Prize in Chemistry 2025 has been awarded to Susumu Kitagawa (Kyoto University, Japan), Richard Robson (University of Melbourne, Melbourne, Australia) and Omar Yaghi (University of California, Berkeley, CA, USA) for their contributions to the discovery and development of metal-organic frameworks.
In 1974, Richard Robson was tasked with creating models composed of wooden balls and poles with which students at the University of Melbourne could create molecular structures. In the process, he instructed the university’s workshop to drill holes in the balls (representing the molecules) in precise locations so that the poles (representing the bonds) could be placed in the positions where the molecules they were modelling would typically form bonds. In doing so, he realized that these positions contained a vast amount of information with which he could predict the structure of new compounds, depending on the molecules involved.
Over a decade later, Robson finally set out to create a new structure, mimicking the crystalline formation of a diamond, but using positively charged copper atoms, which strive to form four bonds like a carbon atom, and 4′,4″,4”’,4””-tetracyanotetraphenylmethane, a four armed molecule, primarily composed of carbon, with a nitrile group at the end of each arm that is attracted to the copper ions. Instead of forming a chaotic network of ions and molecules, it arranged into a crystalline structure as Robson predicted.
The structure of a diamond compared to Robson’s early progenitor of metal-organic frameworks. ©Johan Jarnestad/The Royal Swedish Academy of Sciences
Though similar in the principles of their conformation, Robsons’ new materials contain vast cavities within their structure, compared to a densely packed diamond. He reported this finding in a 1989 article, in which he speculated about the potential of this method to construct new materials with an unimaginable array of properties.
To demonstrate some of the potential applications, Robson forged on with the creation of new structures. He even showed that they could be used for ion exchange by successfully loading his new structure with BF₄⁻ ions, before submerging it in a solution and observing the replacement of these ions with PF₆⁻ ions from the solution, while the structure held its crystalline conformation.
However, these structures, unlike their diamond inspiration, were not robust and often fell apart, causing many to believe that they were ultimately useless, which, in a strange twist of fate, is exactly what drew the next laureate to them.
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Finding use in the useless
During his university studies, Susumu Kitagawa came across the works of ancient Chinese philosopher Zhuangzi in a book by Nobel Laureate Hideki Yukawa, which compelled the reader to question what we believe to be useful, in the hope that in the end, although its use may not be immediately apparent, it may prove to be useful in the future. And so when Kitagawa came across Robson’s work, he was not perturbed by the apparent uselessness of these structures.
Kitagawa set off much in the same vein as Robson, creating new structures with the same process, linking an array of different structures together, primarily using positively charged copper ions as the cornerstone. Kitagawa’s enlightened approach often ran up against the challenge of securing grant funding, where the keepers of the keys tend to show a penchant for “outcome-focused approaches” rather than ancient philosophy. However, Kitagawa persisted and, in 1997, created a 3D structure with cobalt, nickel or zinc ions and a molecule called 4,4′-bipyridine, which contained intersecting channels and could absorb gases without changing shape.
A schematic of Kitagawa’s breakthrough intersecting channel structure. ©Johan Jarnestad/The Royal Swedish Academy of Sciences
However, existing materials composed of silicone dioxide, called zeolites, can also absorb gases, prompting many in the community to again shrug their shoulders and question the utility of a material that could replicate the functions of an existing one, but to a lesser degree.
At this point, Kitagawa realized he would need to budge slightly on his philosophy and lay out the unique qualities of these materials and their utility to secure more considerable funding. So in 1998 he explained his vision in an article, describing the myriad of molecules that can be used to create materials that can therefore deliver different functions. In putting this together, he also realized these materials could be designed to be flexible and pliant, a significant advantage over zeolites, and he soon set to developing flexible iterations of this material.
Meanwhile, another researcher was approaching this field from a different angle. Fed up with the unpredictable nature of typical approaches to the construction of new molecules – combining substances in a container and heating them until they react – Omar Yaghi set out to find a more elegant path. Taking a similar approach to Robson, using rational design to connect chemicals like Lego to form crystalline structures, Yaghi was able to develop two 2D lattice-like materials, one composed of copper and the other cobalt. The cobalt construction was capable of containing ‘guest molecules’ in the spaces of its lattice and when these were occupied, the material could be heated to 350oC without losing its structure. It was in this article that Yaghi first coined the term ‘metal-organic compounds’.
Four years later, the year after Kitagawa’s visionary paper, Yaghi successfully developed MOF-5, a 3D structure that can store gases and maintain its structure up to 300oC, even if the cavities within it are empty. What’s more, the area available within the material was astronomical, far outstripping the gas-containing capabilities of zeolites.
In quick succession, Kitagawa successfully developed a flexible MOF that could be filled with water or methane, flexing as it absorbed, and then returning as it was evacuated, almost like a human lung.
Yaghi continued to work on MOF-5, and by 2003 he had resoundingly demonstrated, with 16 different versions of the material, that it could be altered in a rational manner to produce materials that fulfilled specific functions.
Applications everywhere
Since then, MOFs have exploded in prevalence, with researchers working to develop versions that can resolve many of humanity’s biggest problems, like capturing carbon dioxide, filtering PFAS from water or removing pharmaceutical metabolites from the environment. Yaghi’s own group developed a material that could capture water vapour from the air when left out overnight in the Arizona desert, before releasing it again as the sun heated it in the morning.
The most widespread uses currently in effect are in electronics manufacturing, where MOFs can be used to capture toxic gases involved in the production of semiconductors. They are also being used to go one step further and break down toxic gases, some of which are used in chemical weapons.
The story of MOFs is not quite complete though, as manufacturing at scale still presents a significant challenge. Many companies are working to take these wonder materials from promising breakthroughs, to life changing innovations in analytical chemistry, fuel cell technology, synthesis and catalysis, water purification and environmental remediation, energy conversion and storage, hydrogen generation, food safety, drug delivery and diagnostics, to name but a few.
