Driving Barocaloric Effects in a Molecular Spin-Crossover Complex

(a) Illustration of how pressure-induced thermal changes (barocaloric effects) in a molecular Fe complex Fe[HB(tz)3]2 enable solid-state cooling. (b) High-pressure calorimetry characterization of pressure-induced thermal changes over 10 consecutive cycles that highlight the low-pressure reversibility and large barocaloric effects of this molecular complex.

With direct emissions of volatile hydrofluorocarbon refrigerants currently responsible for ~2% of greenhouse gas emissions, alternative cooling technologies with reduced emission are urgently needed. A team at the Harvard MRSEC led by Mason has discovered a series of iron-based molecular complexes that can be used as solid-state refrigerants. These complexes undergo reversible spin-crossover phase transitions that drive large thermal changes (barocaloric effects) at very low applied pressures—providing a new mechanism to achieve highly efficient solid-state cooling with zero direct emissions. This work has potential to enable effective and sustainable cooling technologies at scale.

Seo, J., J.D. Braun, V.M. Dev, and J.A. Mason, "Driving barocaloric effects in a molecular spin-crossover complex at low pressures," Journal of the American Chemical Society 144 (14), 6493-6503 (2022) open url in new window open pdf in new window

Jarad A. Mason (Chemistry and Chemical Biology)
2022-2023 Harvard MRSEC (DMR-2011754)