This box contains four sealed test tubes with different kinds of metal-organic frameworks (MOFs) developed by Susumu Kitagawa.
The first has the same structure as a honeycomb. It marks the transition from dense network structures to intentionally porous structures.
The second is the first structure that absorbs gas molecules.
The third is the first structure where gas molecules are stored in an orderly way.
The fourth is the first structure where the parts are flexible and can be shifted in relation to each other.
The box is made of paulownia wood from the Aizu region in Japan. This is a dense wood which is silvery-white and insect-resistant. Therefore, it is often used in traditional joinery.
Susumu Kitagawa donated the samples to the Nobel Prize Museum in 2025.
This model, donated by Omar Yaghi, represents a significant turning point in the field of metal–organic frameworks (MOF). The model exhibits the atomic and molecular arrangement of MOF-5, the first example of an ultrahigh-porosity crystalline material. This means that the material has a strong ability to store other substances.
The nodes in this structure consist of metal oxides and the links between them of organic molecules. MOF-5 was developed in 1999. The research on MOF combines two fields in chemistry: inorganic chemistry and organic chemistry.
For Omar Yaghi, the model also symbolises the collaboration with one of his first research students. Yaghi met the student Hailian Li when he was a guest researcher in 1989 at Nanjing University in China. When Yaghi got his first professorship at Arizona State University, Li wrote to him that he had read that Yaghi was working on metal-organic compounds, and he believed he could do substantial work in the field, perhaps even better than Yaghi himself. So, Yaghi offered him a doctoral position. The development of MOF-5 started with an experiment where Li found crystals that he extracted from their solvent. He believed that they were unstable and therefore uninteresting. On Yaghi’s advice, he left the crystals in their solution. When they studied the crystals microscopically, they realised they were stable and this meant that they had made an important discovery. An unforgettable moment!
According to Yaghi, being a mentor is about finding the balance between giving students the freedom to find their own path, and being present and actively ensuring that students do not miss vital discoveries.
Omar Yaghi donated the model to the Nobel Prize Museum in 2025.
