According to a study published in the Journal of the American Chemical Society, a research team from Kumamoto University has effectively created an innovative method for producing switchable magnetic materials by employing hydrogen bonding at the molecular level.
By introducing a chiral carboxylic acid as a hydrogen-bond donor, the team induced precise magnetic switching behavior in cobalt-iron molecular assemblies, controlled by temperature changes. Image Credit: Yoshihiro Sekine, Shinya Hayami, Kumamoto University
This groundbreaking study demonstrates how some metal complexes that were previously insensitive to external stimuli can now demonstrate sharp and complete magnetic transitions by adding chiral hydrogen bonds.
Under the direction of Associate Professor Yoshihiro Sekine of the Priority Organization for Innovation and Excellence, the research team concentrated on developing switchable molecular assemblies made of iron (Fe3+) and cobalt (Co2+) ions, which do not usually react to external stimuli.
The team's innovation incorporates hydrogen bonding using a chiral carboxylic acid, allowing the molecules to switch precisely between paramagnetic and diamagnetic states. These assemblies, known as “Molecular Prussian Blue analogs,” indicate promise for controlled electron transfer between iron ions and cobalt, previously unachieved in conventional materials.
The study's other crucial result is the performance of molecular chirality in the assemblies. Enantiopure hydrogen-bond donor molecules permitted sharp and complete magnetic transitions, whereas racemic mixtures produced disordered structures with broad, incomplete transitions. This emphasizes the significance of precise molecular arrangement in creating functional materials with predictable behavior.
The chiral hydrogen-bonding units are crucial for achieving the cooperative and abrupt phase transitions that we observed. This opens up new avenues for designing switchable materials at the molecular level.
Yoshihiro Sekine, Associate Professor, Kumamoto University
These discoveries could create cutting-edge materials for sensors, magnetic storage devices, and other electronic applications. The research opens a new avenue for creating smart materials and functional molecular machines by demonstrating how minute modifications to molecular structure can result in striking variations in material behavior.
Journal Reference:
Fukushima, R. et. al. (2024) Assembling Smallest Prussian Blue Analogs Using Chiral Hydrogen Bond-Donating Unit toward Complete Phase Transition. Journal of the American Chemical Society. doi.org/10.1021/jacs.4c05065