The story to date: For centuries, chemistry’s fundamental terrain was to craft ever extra advanced molecules but it surely quickly grew to become clear to scientists that they had been all confined to their very own boundaries. The Nobel Prize in Chemistry 2025 honours three scientists who expanded that horizon into an entire new dimension. Susumu Kitagawa, Richard Robson and Omar Yaghi have been feted for growing metal-organic frameworks (MOFs), little molecular scaffolds with huge inner areas the place different atoms and molecules can transfer, react or keep.
What is a MOF?
MOFs are crystalline constructions during which metallic ions function nodes and natural molecules as connectors. The ensuing construction can have monumental inner floor areas — 1000’s of sq. metres per gram — and their pores could be customised to draw or maintain particular molecules.
Chemists classify MOFs as half of a bigger household known as coordination networks however their hallmark is tuneable porosity. By rigorously selecting the constructing blocks, researchers can management the measurement and form of the cavities and the chemical atmosphere inside. As a consequence, MOFs are amongst the most versatile supplies ever created.
What did Robson and Kitagawa do?
In the Nineteen Seventies, Richard Robson at the University of Melbourne was getting ready ball-and-stick fashions to point out college students how atoms join. He realised that the positions of the holes drilled into every atom contained all the data wanted to find out the molecule’s form. If that logic labored for small molecules, he questioned, might or not it’s scaled up?
A decade later, Robson mixed copper ions, which prefer to bond in a tetrahedral association, with an natural molecule bearing 4 arms ending in nitrile teams. To everybody’s shock, as an alternative of a messy tangle, the parts self-assembled right into a diamond-like crystal. This lattice wasn’t dense like diamond however filled with empty cavities, every able to internet hosting different molecules. Robson predicted that such “frameworks” could possibly be tailor-made to entice ions, catalyse reactions and sieve molecules by measurement.
However, Robson’s early crystals had been fragile. Susumu Kitagawa in Japan made them secure and useful. Guided by his philosophy of discovering “usefulness in the useless”, Kitagawa pursued porous supplies even once they appeared too delicate to matter. In 1997, he used cobalt, nickel or zinc ions linked by a bridging molecule known as 4,4’-bipyridine to construct a real three-dimensional MOF. When the materials was dried and refilled, gases akin to methane, nitrogen, and oxygen might move out and in with out damaging the construction.
Kitagawa additionally recognised that MOFs could possibly be comfortable somewhat than inflexible, with versatile molecular joints permitting them to increase, contract or bend round relying on temperature, stress, and the molecules inside.
What was Yaghi’s contribution?
Omar Yaghi in the U.S. gave MOFs their structural energy and reproducibility. Having grown up in modest circumstances in Jordan, Yaghi was fascinated by chemistry’s means to create new types of order. At Arizona State University in the Nineties, he sought a solution to construct prolonged supplies by design, not by probability, utilizing metallic ions as joints and natural molecules as struts.
In 1995, he made the first two-dimensional frameworks linked by cobalt or copper ions that would host different molecules with out collapsing. Four years later, he achieved a landmark with MOF-5, a strong three-dimensional lattice comprised of zinc ions and benzene-dicarboxylate linkers. MOF-5 was sturdy and, notably, just some grams had an inner floor space corresponding to a soccer subject. It was additionally intact when heated to 300°C and emptied of all ‘guest’ molecules.
By the early 2000s, his group had constructed whole households of MOFs with the identical underlying geometry however totally different pore sizes and features.
Why do MOFs matter?
Say you will have a tennis ball with a floor space of X. Say its outer shell is 5 mm thick. What will the whole floor space be while you minimize open the ball? It shall be 2.2-times X (proof out there on request) — which is a bit of illustration of the ‘magic’ of floor areas. The identical ball yielded some floor space first, then with a single modification that didn’t add any new materials yielded 2.2X! This truth explains one half of the attract of MOFs. The different half has to do with how simply chemists could make them for various functions.
A MOF known as CALF-20 can effectively seize carbon dioxide from manufacturing facility exhaust and is already being examined in industrial crops. MOF-303 can harvest ingesting water from arid desert air by absorbing vapour at evening and releasing it in daylight. UiO-67 can take away persistent eternally chemical substances (PFAS) from water. MIL-101 and ZIF-8 can velocity up the breakdown of pollution and recuperate rare-earth metals from wastewater.
In the vitality sector, NU-1501 and MOF-177 can retailer hydrogen or methane safely at average stress, a vital step towards clean-fuel autos. Others function containers for poisonous gases in semiconductor manufacturing and as drug-delivery capsules that launch medicines in response to organic cues.
