The Nobel Prize in Chemistry for this year is out. The winners — Richard Robson, Susumu Kitagawa, and Omar Yaghi — have been honoured for creating molecular constructions with ‘rooms’ in between in which desired gases or chemicals can be stored. One of the laureates, Omar Yaghi, grew up in a one-room house in Amman, with no electricity or running water.The three have “developed a new form of molecular architecture. In their constructions, metal ions function as cornerstones that are linked by long organic (carbon-based) molecules. Together, the metal ions and molecules are organised to form crystals that contain large cavities. These porous materials are called metal-organic frameworks (MOF). By varying the building blocks used in the MOFs, chemists can design them to capture and store specific substances.”Some of the uses of MOFs can be trapping moisture from desert air to get water, or trapping ethylene gas from fruits so that they ripen, and thus spoil, slowly.What Are Metal-Organic Frameworks?MOFs are a class of materials composed of metal ions connected by organic molecules, forming a three-dimensional network with large, porous cavities. This design allows gases and liquids to flow through, making MOFs highly adaptable for various applications.Metals can form bonds in multiple directions, and thus metal ions are the anchors here, like joints in a scaffolding. Organic molecules link them together. Organic molecules are flexible, can form rings and chains, and can be designed to have chemical groups with specific properties.To understand all this better, let’s quickly recap chemistry lessons from school —bonds are formed because atoms want to be stable, that is, have eight electrons in their outer shells. Those that have less than four electrons generally lose them, those with more than four try to gain the missing electrons (the number of electrons available for bonding is called valency of an atom). Organic compounds contain carbon atoms, and carbon’s unique bonding ability allows it to form chains and rings.How did the three scientists create MOFs?It all began in 1974. As the Nobel Prize’s press release explains, “Richard Robson, then teaching at the University of Melbourne, Australia, had been tasked with turning wooden balls into models of atoms, so students could create molecular structures.” He asked the university’s workshop to drill holes in the balls, so that wooden rods, depicting chemical bonds, could be attached to the ‘atoms’. However, every atom bonds in a specific way (depending on whether it is gaining, losing, or sharing electrons) and the holes had to be drilled keeping that in mind.Story continues below this adThis led Robson to the idea: “what would happen if he utilised the atoms’ inherent properties to link together different types of molecules, rather than individual atoms? Could he design new types of molecular constructions?”From here started a long journey, where Robson did manage to create molecular structures, but they were very collapsible.Susumu Kitagawa, working separately and inspired by the principle of “the usefulness of useless”, built sturdier structures, and also showed that gases could pass through the cavities in them.Then there was Yaghi, whose interest in Chemistry was ignited by a random event — he sneaked into a library and the book he picked up happened to be a Chemistry book. Decades later, now a researcher in the US, he set about on a mission to make chemical reactions less random. He wanted them to be predictable and not create a lot of unwanted byproducts, rather like using legos to arrive at a predictable outcome.Story continues below this adHis research group succeeded when they started combining metal ions with organic molecules. “In 1995, Yaghi published the structure of two different two-dimensional materials; these were like nets and were held together by copper or cobalt. The latter could host guest molecules in its spaces and, when these were fully occupied, it was so stable that it could be heated to 350°C without collapsing. Yaghi describes this material in an article in Nature where he coins the name “metal–organic framework”,” the press release says.Real-world applications of MOFsThe unique properties of MOFs have led to their application in various fields:Water harvesting: MOFs can extract water from dry air, offering a potential solution for water-scarce regions.Pollutant Removal: They can filter out harmful substances like PFAS from water, addressing environmental contamination.Story continues below this adCarbon capture: MOFs are effective in capturing carbon dioxide, aiding in efforts to mitigate climate change.Hydrogen storage: Their porous nature allows for the safe storage of hydrogen, crucial for clean energy applications.Who are the three Chemistry laureates?Susumu Kitagawa, was born in 1951 in Kyoto, Japan. He is a Professor at Kyoto University, Japan.Richard Robson was born in 1937 in Glusburn, UK. He is a Professor at University of Melbourne, Australia.Story continues below this adOmar M Yaghi was born in 1965 in Amman, Jordan. He is a Professor at University of California, Berkeley, USA.