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Updated: Mar 24, 2026
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Author Spotlight: Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
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Reversible I2 Uptake Induces Record-High Spin-Crossover Hysteresis in a Fe(II) Hofmann-Type MOF
Mario Pacheco1,2, Higinio Maqueda-Márquez1, Annena Jesuman1
1Institut De Ciència Molecular (ICMol)-Departament De Química Inorgànica, Universitat De València, Paterna, Spain.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|March 23, 2026
Summary
Guest-induced chemical pressure in metal-organic frameworks (MOFs) amplifies spin-crossover (SCO) thermal hysteresis. Iodine uptake in a Hofmann-type MOF created record-wide hysteresis, enabling control over bistable spin states.
Area of Science:
- Materials Science
- Chemistry
- Physics
Background:
- Controlling bistable spin states in iron(II) spin-crossover (SCO) frameworks is crucial for developing molecular switches and memory devices.
- Existing methods for controlling SCO bistability often face limitations in reversibility and tunability.
Purpose of the Study:
- To investigate guest-induced chemical pressure as a strategy to control and amplify thermal hysteresis in SCO materials.
- To explore the impact of guest molecule loading on SCO behavior and hysteresis width.
Main Methods:
- Utilized a flexible Hofmann-type metal-organic framework (MOF), [Fe(pz)Pd(CN)4].
- Applied vapor-phase iodine uptake to induce chemical pressure within the MOF.
- Performed structural (X-ray diffraction) and magnetic (SQUID magnetometry) analyses to characterize SCO behavior.
Main Results:
- Achieved a record-wide thermal hysteresis of 120 K in the iodine-loaded MOF, significantly exceeding previous values.
- Demonstrated that lattice compression by iodine enhances cooperative spin transitions, stabilizing both high-spin and low-spin states.
- Observed multistep SCO with asymmetric hysteresis upon partial iodine loading and symmetric hysteresis with extreme bistability upon full saturation.
Conclusions:
- Guest capture provides a direct, reversible, and generalizable method to control SCO bistability.
- This approach offers a promising design principle for creating multifunctional porous materials with tunable spin-crossover properties.
Keywords:
Fe(II) coordination compoundsI2 uptakechemical pressurehost‐guestmetalorganic frameworksspin crossoverMore Related Videos
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