Water molecules act as magnetic messengers in new study

Hydrogen bonds link distant ions

A new study published in the journal Inorganic Chemistry reveals that water molecules serve as secret messengers for magnetism. National Taipei University of Technology and researchers from Tohoku University's Institute of Multidisciplinary Research for Advanced Materials joined forces to achieve this discovery. Tiny shifts in water orientation flip magnetic partnerships between metal ions that are not directly bonded. Associate professor Kazuhiro Nawa stated that distant magnetic moments interact via hydrogen bonding which can be controlled by water orientation.

Cooling creates ordered magnetic pairs

For their investigation, the team synthesized two fluorinated pincer-type copper(II) complexes called 2FH-CuCl₂·H₂O and 3F-CuCl₂·H₂O. They used single-crystal X-ray diffraction and neutron diffraction at the 4G-GPTAS instrument at the JRR-3 research reactor to examine structural changes. At room temperature water molecules point in disordered directions but snap into an ordered arrangement below 260 K. This reshuffling splits the hydrogen bonding pattern into two distinct types and pairs up neighboring molecules.

Measurements confirm antiferromagnetic pairing

Susceptibility displayed wide peaks near 5 to 7 K in magnetic readings before falling toward zero. This signature indicates antiferromagnetic pairing where magnetic moments of paired molecules cancel each other out. Calculations using density functional theory identified the hydrogen bonding network as the probable route for transmitting that interaction. A model describing magnetic pairs with interaction strengths near 10 K matches the data.