Tarragona (Spain), October 26e 2022 – A new paradigm has emerged at ICIQ, demonstrating that thermal hysteresis is maintained on single molecules in liquid solution. It has been a really complex and long journey where clearly the expertise and knowledge of a team of three research groups has been the key to success.
Hysteresis is the tendency of a material to retain one of its properties even when the stimulus that generated it disappears. An illustrative case is when the iron is exposed to a magnetic field. It will remain magnetized indefinitely until some energy is transferred to the system (a magnetic field in the opposite direction for example). This magnetic memory effect is the basis for storing information on certain types of hard drives.
The advantage of small components capable of storing information is clear in terms of space and power consumption. So far, single molecule magnets (SMMs), promising molecular materials that represent the ultimate unit of miniaturization, have been developed. However, they required very low temperatures (–193 ºC) to function properly because the magnetic memory effect is quickly lost through nanoscale thermal activation.
The occurrence of a memory effect at the single molecule level, even after dilution, was found in a spin-crossing molecule (SCO), a polyanionic iron complex. The classical and well-accepted elastic model for SCO systems excluded the occurrence of molecular bistability, since a memory effect would only be allowed in case of bulk crystallographic phase transition. Thus, this discovery shatters previous expectations.
The presence of a memory effect in this polyanion around room temperature has been confirmed by extensive complementary experimental evidence, including magnetic and spectroscopic techniques, both in dilute solid mixtures and in the liquid phase. All have consistently demonstrated the onset of a true single-molecule memory effect. These results represent a successful team effort, after almost eight years, of the groups of Professor José Ramón Galán-Mascarós, Professor Mónica H. Pérez-Temprano and Professor Julio Lloret-Fillol.
“Extraordinary claims require extraordinary evidence, which can only be provided by a complementary effort of multiple techniques and multiple backgrounds. ICIQ leads, but we were lucky to bring together a unique and interdisciplinary team,” says Galán-Mascarós. “Our long experience in NMR to elucidate reaction mechanisms in organometallic chemistry has been essential to study this new phenomenon. A very different problem that we could successfully approach with a fresh mind, looking outside the box,” concludes Professor Pérez-Temprano.
The computer analysis, led by Professor Eliseo Ruiz (University of Barcelona), identified the origin of this new phenomenon with the appearance of strong intra- and supra-molecular interactions, capable of slowing down the relaxation processes at the level of the single molecule, and thus opening a kinetic thermal hysteresis. Obviously, the previous SCO theory is not refuted, but the occurrence of this unexpected molecular property could not be predicted until this time.
The discovery of this slow relaxation process, which seemed impossible, is now a matter of fundamental research, but these results could certainly represent a revolution in the field of spin transition phenomena, since the unique molecules of SCO open exclusive opportunities for the storage of molecular data at technologically relevant temperatures. A new way of storing multifunctional information (optical or magnetic) has emerged and suggests that this is the tip of a large iceberg of new possibilities.
The impossible is the science that has not yet been discovered and at the ICIQ an impossible has been unearthed.
Reference article:
Moneo-Corcuera, A., Nieto-Castro, D., Cirera, J., Gómez, V., Sanjosé-Orduna, J., Casadevall, C., Molnár, G., Bousseksou, A., Parella, T. , Martínez-Agudo, JM, Lloret-Fillol, J., Pérez-Temprano, MH, Ruiz, E. & Galán-Mascarós, JR Molecular memory near room temperature in a polyanionic iron complex. Chemistry. https://doi.org/10.1016/j.chempr.2022.09.025
Research method
Experimental study
Research subject
Not applicable
The title of the article
Molecular memory near room temperature in a polyanionic iron complex
Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of press releases posted on EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
#Unprecedented #Hunt #Memory #Molecules #Room #Temperature