Periodic Reporting for period 1 - LUX-INVENTA (Bringing molecular photomagnets to light - achieving magnets through visible light excitation at room temperature)
Reporting period: 2022-11-01 to 2025-04-30
Magnets and light are everywhere and yet their combinations are not common at all. Light is the source of all life on Earth while magnets make everyday life much easier – they are the key components in washing machines, vacuum cleaners, electric vehicles, hard disk drives in our computers, even MRI scanners in hospitals. Moreover, the very sophisticated elements of synchrotron storage rings like undulators or wigglers incorporate magnets. Photomagnets – magnets responsive to light, on the other hand, remain completely unknown (internet search leads only to personalized fridge magnets with a choice of pictures/photos, hence – 'photomagnets'). Moreover, while the global permanent magnet market was worth 22.2 billion USD in 2023, the global photomagnet market was worth basically nothing (excluding the aforementioned 'fridge photomagnets'). Therefore, there is a lot of room for improvement and one of the long-term objectives of the proposed research is 'to bring the real photomagnets into the spotlight' and enable their way into home appliances or at least into sophisticated scientific equipment that would allow discovery of better materials in the future.
The terms 'photomagnetism' and 'photomagnetic effect', referring to the change of the magnetic moment in response to visible light in photomagnets, were coined by the pioneers in the field of molecular magnetism: Hashimoto, Miller, Verdaguer and Dei. Noteworthy, its discovery is a consequence of the seminal work of Hauser et al. on the light induced excited spin state trapping (LIESST) effect in octahedral iron(II) complexes showing spin crossover (SCO) behavior and the discovery of the first room temperature molecular magnets obtained via bottom-up approach. The term 'photomagnetic effect' applies to all types of magnetic systems responsive to light: diamagnetic, paramagnetic as well as magnetically ordered ones. It relies on the observation that absorption of a photon by a specific part of a molecular system (a photomagnetic chromophore) can lead to a series of physical events resulting in a spin state change. Construction of molecular materials based on photomagnetic chromophores will lead to photomagnets - compounds that get magnetized when exposed to visible light. Hence, the major objective of LUX-INVENTA is the design and synthesis of room-temperature photomagnets – paramagnetic compounds that upon exposure to visible light become reversibly magnetized.
Currently, photomagnets working at room temperature are unknown. Hence, their possible applications remain solely theoretical. However, one can easily think of the possible technologies based on photomagnets. One of the most appealing ones would be the construction of a motor that does not need electricity to run - only light. While this idea seems quite wild at the moment, it might come to fruition once suitable photomagnetic materials are discovered. Other concepts involve photomagnetic valves that could be operated completely remotely using visible light (e.g. lasers), in opposition to electromagnetic valves which require electrical contacts (physical connections). Finally, thin photomagnetic layers could be a perfect alternative in information storage devices based on conventional magnets, with the possibility of writing/reading data using the combination light and magnetic fields. The LUX-INVENTA research team aims to discover photmagnets working at room temperature. After achieving this extremely challenging goal, the possibility of constructing a proof-of-concept photomagnetic device will be investigated.
The terms 'photomagnetism' and 'photomagnetic effect', referring to the change of the magnetic moment in response to visible light in photomagnets, were coined by the pioneers in the field of molecular magnetism: Hashimoto, Miller, Verdaguer and Dei. Noteworthy, its discovery is a consequence of the seminal work of Hauser et al. on the light induced excited spin state trapping (LIESST) effect in octahedral iron(II) complexes showing spin crossover (SCO) behavior and the discovery of the first room temperature molecular magnets obtained via bottom-up approach. The term 'photomagnetic effect' applies to all types of magnetic systems responsive to light: diamagnetic, paramagnetic as well as magnetically ordered ones. It relies on the observation that absorption of a photon by a specific part of a molecular system (a photomagnetic chromophore) can lead to a series of physical events resulting in a spin state change. Construction of molecular materials based on photomagnetic chromophores will lead to photomagnets - compounds that get magnetized when exposed to visible light. Hence, the major objective of LUX-INVENTA is the design and synthesis of room-temperature photomagnets – paramagnetic compounds that upon exposure to visible light become reversibly magnetized.
Currently, photomagnets working at room temperature are unknown. Hence, their possible applications remain solely theoretical. However, one can easily think of the possible technologies based on photomagnets. One of the most appealing ones would be the construction of a motor that does not need electricity to run - only light. While this idea seems quite wild at the moment, it might come to fruition once suitable photomagnetic materials are discovered. Other concepts involve photomagnetic valves that could be operated completely remotely using visible light (e.g. lasers), in opposition to electromagnetic valves which require electrical contacts (physical connections). Finally, thin photomagnetic layers could be a perfect alternative in information storage devices based on conventional magnets, with the possibility of writing/reading data using the combination light and magnetic fields. The LUX-INVENTA research team aims to discover photmagnets working at room temperature. After achieving this extremely challenging goal, the possibility of constructing a proof-of-concept photomagnetic device will be investigated.
The work performed so far include the characterization of two paramagnetic cyanide-bridged coordination frameworks based on manganese(II) and octacyanotungstate(IV) which can be reversibly transformed into each other by the reversible sorption of water molecules. Such a behavior is known as a paramagnetic sponge behavior. Photomagnetic studies revealed that the fully hydrated form shows no response to visible light irradiation, while the anhydrous one demonstrates an unprecedented increase of magnetization upon exposure to blue light at temperatures below 110 K. Detailed photomagnetic measurements revealed photo-induced magnetic hysteresis loop persisting up to 110 K. This is the highest magnetic ordering induced by light ever reported in the literature. Moreover, the photoswitching was demonstrated well above the boiling point of liquid nitrogen, which is the limit for any practical applications.
Secondly, our photomagnetic studies extended beyond the known photomagnetic building blocks, enabled the identification of heptacyanomolybdate(III) as the new most promising photomagnetic chromophore. A complete experimental and theoretical study performed for the potassium salt of heptacyanomolybdate(III) shows that it undergoes a photoswitching process involving the unprecedented change of the coordination sphere of the molybdenum(III) ion. This transformation induces a spin state change which paves the way for the development of a new class of photo-switchable high-temperature magnets and nanomagnets. The manuscript (author’s accepted version) has been deposited with the ChemRxiv repository and is available free of charge under the CC BY NC 4.0 license here: DOI: 10.26434/chemrxiv-2024-v4j8t.
One of the peak achievements of the LUX-INVENTA research team was the rational design and successful isolation of a completely new and yet very simple organic molecule called tripak. The unique redox properties of tripak enabled its isolation in five different states accommodating up to six additional electrons. These states can be reached by applying a small electrical potential enabling electro-switching between completely different properties: record strong anion-π binding of halides, molecular qubit behavior, red fluorescence and chemically unique diradicaloid character. These results were published as an open access research article in the Cell Press journal Chem (https://doi.org/10.1016/j.chempr.2023.12.024(opens in new window)). Moreover, the preparation of tripak inspired a side research task in which a very simple thermodynamically unstable oligomeric carbon monoxide molecule was successfully isolated via extremely strong anion-π interactions. This important observation suggests that anion-π interactions which up to now were considered to be weak and non-covalent in nature, can indeed be as strong as covalent bonds.
Secondly, our photomagnetic studies extended beyond the known photomagnetic building blocks, enabled the identification of heptacyanomolybdate(III) as the new most promising photomagnetic chromophore. A complete experimental and theoretical study performed for the potassium salt of heptacyanomolybdate(III) shows that it undergoes a photoswitching process involving the unprecedented change of the coordination sphere of the molybdenum(III) ion. This transformation induces a spin state change which paves the way for the development of a new class of photo-switchable high-temperature magnets and nanomagnets. The manuscript (author’s accepted version) has been deposited with the ChemRxiv repository and is available free of charge under the CC BY NC 4.0 license here: DOI: 10.26434/chemrxiv-2024-v4j8t.
One of the peak achievements of the LUX-INVENTA research team was the rational design and successful isolation of a completely new and yet very simple organic molecule called tripak. The unique redox properties of tripak enabled its isolation in five different states accommodating up to six additional electrons. These states can be reached by applying a small electrical potential enabling electro-switching between completely different properties: record strong anion-π binding of halides, molecular qubit behavior, red fluorescence and chemically unique diradicaloid character. These results were published as an open access research article in the Cell Press journal Chem (https://doi.org/10.1016/j.chempr.2023.12.024(opens in new window)). Moreover, the preparation of tripak inspired a side research task in which a very simple thermodynamically unstable oligomeric carbon monoxide molecule was successfully isolated via extremely strong anion-π interactions. This important observation suggests that anion-π interactions which up to now were considered to be weak and non-covalent in nature, can indeed be as strong as covalent bonds.
While the goal of achieving room-temperature photomagnetism has yet to be reached, the LUX-INVENTA project has already pushed the limits of photomagnets towards an applicable temperature range and demonstrated a completely new photoswitching mechanism based on a reversible photodissociation reaction occuring in the solid state. Moreover, the search for novel organic molecules suitable for the observation of charge-transfer induced photomagnetic switching has spawned a unique and yet very simple tripak molecule, which seems to be an extremely versatile platform for the construction of completely new magnetic coordination polymers.