MOFs – getting inspired for chemical discoveries
In 2012, BASF received the French Pierre Potier Award for its research on metal organic framework or MOFs: thanks to a new manufacturing process it is possible for the first time to produce MOFs on industrial scale - that is several tons - and without using solvents. Our own Manuela Gaab explained the workings of MOFs in an earlier blog entry. But who is behind these mysterious frameworks with their sponge-like surfaces? Manuela talked to the forefather of MOFs, Omar M. Yaghi (University of California, Berkeley).
Toward the end of 1990 the US chemist Yaghi made a groundbreaking discovery: the metal organic frameworks (MOFs). BASF researchers contacted him after reading his 1999 article in the science journal Nature and have been collaborating with Professor Yaghi ever since on the synthesis of metal-organic frameworks. The aim is to develop MOFs with the largest possible surface area and storage density.
Manuela Gaab: Prof. Yaghi, which of your accomplishments do you rank being most important?
Yaghi: The most important discovery is the ability to combine and link together organic and inorganic units to make a wide range of MOFs. The simple synthesis, large number of units which could be used and the vast number of possible structures that could be made make MOFs an extensive class of materials.
How did you discover the first MOF (MOF-5)?
In the reaction vessel we found two batches of crystal: one batch at the bottom of the vessel had a lot of crystals while the second batch appearing near the top of the liquid (at the meniscus) had only a couple of tiny crystals. We focused our attention on the latter few which turn out to be MOF-5 (surface area >3500 m2/g); far more interesting the MOF found in the first batch (MOF-2, surface area 270 m2/g).
Where do you get your inspiration for new MOF concepts?
While walking alone or sometimes in bed.
Which MOF design is suited best for gas storage applications?
The best design would be a structure with very high surface area (porosity) but with pore metrics suited to maximize the interaction of that specific gas to the MOF. Optimal pore size for hydrogen is approx. 0.7 nm and for methane 1.2 nm.
Which are the highlights in your cooperation with BASF?
I recognized early on when I discovered MOFs that to be able to commercialize them, a large chemical like BASF is needed to develop their industrial chemistry. It was Dr. Ulrich Mueller's(1) vision which allowed us to enter into a productive collaboration to develop the industrial chemistry of MOFs. We worked and still working very hard, now for 11-12 years. It's been a delight to see how jointly with BASF we took these materials from laboratory to industry to the market. The highlight of my collaboration with BASF has been the interaction with the people here at BASF. Ulrich Mueller and his team are superb individuals.
1 Dr. Ulrich Müller leads the MOF research team at BASF