Alumni Interview: Omar Yaghi

“We discovered that metal-organic frameworks could make drinking water in humid climates where there’s no clean water,” says Omar Yaghi. “Water harvesting is being commercialized by Atoco, a start-up I founded. We have machines that can deliver up to 2,000 liters a day.” (Image by Brittany Hosea-Small)

When I first arrived at Illinois to do my Ph.D. in chemistry with Walter Klemperer, he gave me a task: to make a perturbation on an existing molecule using a simple reaction. It took me a whole year of failures and doubts.

When I thought I’d finally succeeded, I put the lovely, orange sample in the analysis machine and got something unanticipated: a disgusting, brown gunk. A postdoc suggested I throw it away, but I didn’t want to toss a year of work. Instead, I set it up for what’s called crystallization.

In the morning, I found beautiful, ruby-red crystals. I showed Walter, who said, “You just made a completely new compound.”

The experience reminded me that sometimes the thing you’re aiming toward might turn out to be something else—and that “something else” could be a door opening.

I was born and raised in Amman, Jordan, in a refugee family of 10 children, in a house with no electricity or water. My father had a butcher shop and worked hard. He emphasized that a job is not complete until it’s done well.

My parents spent everything they had on private-school tuition. When I was 10, I slipped into the school library, picked up a book, and saw these beautiful drawings. I found out they were molecules, and bit by bit, I fell in love with chemistry.

My father saw few opportunities for me in Jordan and sent me to the U.S. before I finished high school. I went to Hudson Valley Community College in Troy, N.Y., then transferred to SUNY Albany (now the University at Albany). There, in the lab, I was in heaven.

In those days, we chose graduate programs by leafing through catalogs. Walter Klemperer’s page featured a beautiful molecule that looked like a soccer ball. I wanted to work on that, so I visited Illinois to see if he was a nice guy.

He was, but I quickly learned he’s also a tough mentor. If my father sculpted my work ethic, Walter sculpted my mind. He made me the scientist I am today, one who’s careful and rigorous. He taught me not to follow others’ footsteps, but to pave my own path.

After completing my Ph.D. and postdoc, I believed you could make materials by putting molecules together like Legos. It was taken as an article of faith by chemists that these materials would never assemble in an ordered fashion. But I thought, “I’m going to make it work.”

“I believed you could makematerials by putting molecules together like Legos.” —Omar Yaghi, PHD ’90 LAS

I went to Arizona State University and built up a lab. At the time, metal-organic compounds had been published, but they didn’t show any interesting properties. When you tried to explore their porosity, they collapsed.

I discussed this with a student, Guangming Li, and she found a recipe to make crystalline structures from very strong bonds. Another student came in and showed that they could be made porous. That was really the opening of the field, in the mid-1990s.

Metal-organic frameworks, or MOFs, are networks, almost like a fishing net. With a fishing net, you have intersections linked together to make a whole structure. We can put molecules where the intersections are and link them, and now you have a molecular framework on the microscopic level.

In 1999, my colleagues and I published a paper showing that MOFs can have ultra-high porosity. The way I describe this is like taking a football field and collapsing it on itself until it’s one gram of material. It’s the size of a sugar cube, but still has the surface area of a football field. These things are scaffolding, like honeycombs, and they can bind hydrogen, carbon dioxide, or water.

You can build them in a rational way and modify them with precision. This has transformed the way we make materials—the base of all civilizations. We even name our ages after them: the Stone Age, the Bronze Age. When the Nobel Committee awarded me, Susumu Kitagawa, and Richard Robson the 2025 Nobel Prize, they said that many people think we are living in the MOF Age.

We can use MOFs to harvest drinking water from desert air. When I was growing up, the city would release water once or twice every two weeks for an hour or two. When it came, you filled every container. When we were measuring water uptake by MOFs, I saw what nobody else could see in the data, because I’d lived in that environment.

We are also using MOFs to take carbon dioxide out of power plants so it’s not released into the air, to take CO₂ out of the air, and to store hydrogen to make clean energy.

If I started back in the early 1990s by saying, “I want to fix the CO₂ problem,” would I have invented MOFs? I’m not sure. As scientists, we start by addressing a very difficult intellectual challenge. Once you succeed in that, you see that you have many, many applications—some of which you would never have imagined.