10 October 2017

Reversible magnetic switching in multifunctional material

This cobalt(II) coordination complex changes color and magnetic properties with the addition of water. This cobalt(II) coordination complex changes color and magnetic properties with the addition of water.

With just a drop of water, a cobalt-based material changes both color and magnetic properties.

What did scientists discover?

Scientists created a new molecular material built around a cobalt ion whose properties can be “switched” on or off with the simple addition or removal of water.

To make the material, which is a cobalt(II) coordination complex, the scientists placed a cobalt ion inside an organic molecule that embeds the cobalt ion with special, coordinating bonds. They discovered that by adding or removing a water molecule, they could change not just one, but two properties of the complex.

Without water (above left), the complex is deep red and, after being magnetized in a magnetic field, demagnetizes slowly as the spins of its electrons gradually relax.

When a water molecule is added (above right), the complex turns orange-green, and demagnetizes rapidly (the electron spins relax quickly).

Why is this important?

Not only does the absence or presence of water bring about two different changes in the complex, but those changes are also reversible. So water is an easy, convenient switch that turns the optical and magnetic properties of the compound on and off.

This new class of molecular nanomagnets offers fascinating possibilities for designing multifunctional molecular materials, with potential applications that include information storage, quantum computing and nanosensors.

Who did the research?

J. Vallejo1, E. Pardo1, M. Viciano-Chumillas1, I. Castro1, P. Amorós1, M. Déniz2, C. Ruiz-Pérez2, C. Yuste-Vivas1, J. Krzystek3, M. Julve1, F. Lloret1, and J. Cano1

1U. Valencia, Spain; 2U. de La Laguna, Tenerife, Spain; 3MagLab, Florida State University, USA

Why did they need the MagLab?


This research was conducted in the Transmission Spectrometer in the EMR Facility.

High-field electron paramagnetic resonance (EPR) studies provided insights at the molecular level into the different magnetic properties of the two compounds. The high fields and frequencies for EPR at the MagLab provide enhanced spectral resolution unavailable elsewhere. This enables resolution of all features in the experimental EPR spectrum (black in bottom figure, compared to red simulation).

Details for scientists


This research was funded by the following grants: G. S. Boebinger (NSF DMR-1157490); MICIIN (Spain); Generalitat Valenciana (Spain); ACIISI (Spain)

For more information, contact Stephen Hill.


  • Research Area: Magnetism and Magnetic Materials
  • Research Initiatives: Materials
  • Facility / Program: EMR
  • Year: 2017
Last modified on 12 October 2017