VU Professor Mantas Šimėnas, Co-Author with a Chemistry Nobel Laureate: Physicists Help Explain Chemists’ Discoveries

When the Nobel Committee awarded this year’s Chemistry Prize for the development of metal–organic frameworks (MOFs), physicists at Vilnius University (VU) were not surprised: ‘Nobel recognition in this field was long expected – it’s a major area not only in chemistry but also in physics,’ said Prof. Mantas Šimėnas from the VU Faculty of Physics.

He has been studying these structures for over a decade and continues to research them to this day. Last year, his work on advancing electron paramagnetic resonance (EPR) techniques used in MOF studies earned him €2.5 million in funding from the European Research Council (ERC).

A publication with a future Nobel laureate

The pioneers of MOF research – Japanese chemist Prof. Susumu Kitagawa, American Prof. Omar Yaghi, and Australian Prof. Richard Robson – were honoured with this year’s Nobel Prize in Chemistry for developing this new class of porous materials. One of them, Prof. Kitagawa, has co-authored scientific publication with Prof. Šimėnas.

‘I had heard of Prof. Kitagawa long before – he’s a major figure in MOF research. A decade ago, when I was still a doctoral student, my supervisor, Prof. Jūras Banys, and I attended the Pacifichem conference in Hawaii, where I met a member of Kitagawa’s research team. Our discussion sparked the idea of collaborating; we realised their system could be very interesting for our magnetism studies. I asked for some samples, they synthesised and sent them, and we conducted the experiments. Soon after, we co-authored a paper showing how ‘guest’ molecules inside MOF pores can alter a material’s magnetic properties,’ recalled the VU physicist.

The study was published in The Journal of Physical Chemistry. According to the researcher, working alongside such a prominent scientist while preparing the publication and obtaining the first results was an immensely rewarding experience for him as a young doctoral student: ‘If someone had asked me back then whether he would one day gain recognition from the Nobel Committee, I would have said a firm ‘yes’ without hesitation.’

Chemistry creates, physics explains

Although the development of porous MOF structures earned the Nobel Prize in Chemistry, it is physicists who help explain how these materials actually behave. Researchers at the VU Faculty of Physics focus not on the synthesis but on the properties of MOFs – the ways in which they respond to their environment and how their structure, electrical, and magnetic characteristics change.

‘When we introduce gas molecules into the pores of these materials, we can observe how they attach to the metal centres and how this affects the magnetic properties. When the molecules are released, everything returns to its initial state. These reversible changes make it possible to design sensitive gas sensors,’ remarked Prof. Šimėnas.

To understand what happens inside the material, scientists combine two complementary methods: EPR spectroscopy and dielectric spectroscopy.

EPR spectroscopy makes it possible to observe the minute magnetic forces between atoms or ions within a crystal lattice. It reveals how these centres respond to external factors such as temperature changes or the penetration of gas molecules into the pores. In other words, it offers a microscopic view of where magnetism, catalysis, or gas absorption begins.

Meanwhile, dielectric spectroscopy provides a macroscopic picture, showing how the entire hybrid architecture, which is composed of organic linkers, responds to an electric field. It shows how these linkers move, oscillate, or shift position as the material interacts with external factors.

‘We use EPR to investigate metal centres and dielectric spectroscopy to examine linkers. This allows us to see both sides of the hybrid system. Some of the MOF structures we’ve studied even show ferroelectric properties, bringing them closer to functional electronic materials where electric and magnetic domains interact,’ said the VU researcher.

Thus, the structures developed by chemists become physics experiments in VU laboratories – experiments that deepen understanding of how materials behave and uncover new possibilities for their application.

From a strange signal to a quantum discovery

During his doctoral studies – the same period when his collaboration with Prof. Kitagawa’s team started – Prof. Šimėnas also examined another, much denser MOF structure: ‘The pores were so narrow that the molecules inside couldn’t really escape. Moreover, in one EPR spectrum, we detected a very strange signal that we couldn’t explain. My supervisor, Prof. Banys, joked that I’d just broken his understanding of physics!’.

The mysterious signal haunted the physicist for years. To solve the puzzle, he sought advice from leading EPR specialists in Switzerland and Germany who joined the research. Eventually, they discovered that this effect was caused by rotational tunnelling of methyl groups – a quantum phenomenon where a chemical group rotates through a barrier as if unhindered.

‘This was the first time this tunnelling effect was directly observed using pulsed EPR. We published the results in Science Advances. This was a significant publication for physics research in Lithuania,’ he said.

Interestingly, the finding resonates with this year’s Nobel Prize in Physics, which recognised work on tunnelling phenomena at the macroscopic scale. While Nobel laureates studied the same principle on a large scale, VU physicists observed it at the molecular level, revealing yet another way quantum effects manifest in matter.

Hybrid materials and the future of quantum technologies

Although MOFs remain an important field, Prof. Šimėnas’ group today focuses on next-generation hybrid structures and quantum technology applications: ‘While we did a lot of MOF research five to ten years ago, now we’re more focused on hybrid perovskites – materials that, like MOFs, contain metal centres but have entirely different electronic properties.’

According to the physicist, these materials hold promise for high-efficiency, low-cost solar cells and LEDs.

Research in this field is significantly strengthened by the ERC Starting Grant – €2.5 million for Prof. Šimėnas’ project aimed at increasing the sensitivity of EPR spectroscopy. This gives the scientist and his team the opportunity to develop new methods and apply them in the analysis of hybrid materials and quantum phenomena.

‘Vilnius University now has one of the most advanced EPR laboratories and strong partnerships stretching from Germany and the UK to the US and Japan. We strive to compete on a global scale – not just in terms of equipment but also in terms of ideas,’ concluded Prof. Šimėnas.