Oct 8th 2025|3 min read
IF YESTERDAY’S ANNOUNCEMENT of the Nobel prize in physics—for developments in quantum mechanics that helped give birth to quantum computers—was greeted with general bafflement, today Sweden’s Royal Academy of Science was taking no chances. The chemistry committee arrived in the portrait-laden press room heavily armed with metaphors, analogies and examples of practical applications.
The prize was given to three researchers—Kitagawa Susumu at Kyoto University, Richard Robson at the University of Melbourne and Omar Yaghi at the University of California, Berkeley—for their work on metal-organic frameworks (MOFs). These are a bit like hotels for chemicals, said Heiner Linke, who chairs the Nobel Committee for Chemistry. Or perhaps self-assembling houses, added Olof Ramstrom, another committee member. Or the bottomless handbag carried by Hermione Granger in the “Harry Potter” books.
Analogies aside, the most straightforward way to think of MOFs is as artificial crystals—substances whose molecules are organised into a regular, repeating structure. As their name suggests, they are made of metallic clusters spaced at regular intervals, linked to each other with long, thin organic molecules (in chemistry, “organic” means any molecule that contains at least one carbon and one hydrogen atom). But it is the empty space in that molecular scaffolding which makes MOFs so interesting. Size the gaps correctly and an MOF can attract and store large quantities of other, “guest” chemicals—hence Dr Linke’s hotel analogy. That makes them useful for everything from removing carbon dioxide from industrial smokestacks to extracting water from dry desert air.
Dr Robson was honoured for helping pioneer the field. Inspired in the 1970s by the ball-and-stick models familiar to generations of chemistry students, he worked out how to persuade copper ions and a chemical called tetracyanotetraphenylmethane to assemble themselves into a substance with the same pyramidal crystalline structure as diamonds, but with much bigger cavities in its crystal lattice. Not only a house for chemicals, in other words, but one that will happily build itself given the right conditions.
Dr Kitagawa, meanwhile, was given his gong for helping to persuade chemists of the promise of these then-new substances. As is often the case in science, Mother Nature had got there first. Chemists already knew about zeolites—substances found in volcanic rocks that likewise have crystalline structures with capacious gaps which can be used to capture other substances. Dr Kitagawa’s work helped convince the field that MOFs had big advantages over their naturally occurring rivals.
For one thing, zeolites are rigid solids. Dr Kitagawa demonstrated that MOFs could be made flexible if desired. And because MOFs are designed from scratch, their chemistry can be tweaked to make them adept at caging a particular target molecule. The near-infinite variety of organic chemistry means that the linking molecules, in particular, can be tweaked to do almost anything. Some MOFs have linkages which contain catalysts, meaning they can break down the substances they absorb into simpler components.
Dr Yaghi was honoured for his work in making those possibilities real. The committee flagged his creation in 1999 of a substance known as MOF-5, described as the “paragon and showcase of the entire field”. The hollow structures of zeolites and MOFs mean that—like Miss Granger’s handbag—even small amounts can boast vast internal surface areas. A gram of zeolite might contain several hundred square metres of surface area within itself. MOF-5, by contrast, can manage nearly 3,000 square metres per gram. It is stable at temperatures up to 300°C, and the size of its cavities can be tweaked to accommodate all sorts of molecular guests.
These days MOFs are a hot topic. Researchers have created substances that can pull oil spills out of water, store large quantities of hydrogen or methane, remove PFAS—a class of troublesome pollutants—from drinking water, cage drugs before releasing them at specific locations in the body, and even absorb and enzymatically break down antibiotics in the environment. A new and promising field of chemistry, in other words, even if it is one that is, as Dr Ramstrom quipped, “full of holes”. ■
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