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Guest-Induced Multistep to Single-Step Spin-Crossover Switching in a 2-D Hofmann-Like Framework with an
Manan Ahmed1, Kasun S A Arachchige2, Zixi Xie3
1School of Chemistry, The University of New South Wales, Sydney 2052, Australia.
Inorganic Chemistry
|July 21, 2022
Summary
Subtle guest modification in a 2-D Hofmann-like framework [Fe(furpy)2Pd(CN)4]·nG influences spin-crossover behavior. The presence of ethanol alters the framework symmetry and transition mechanism, impacting magnetic properties.
Area of Science:
- Coordination Chemistry
- Materials Science
- Supramolecular Chemistry
Background:
- Hofmann-like frameworks are known for their structural versatility and potential applications in molecular magnetism.
- Spin-crossover (SCO) materials exhibit a reversible switch between low-spin and high-spin states, tunable by external stimuli.
- Guest molecules within frameworks can significantly influence structural and electronic properties.
Purpose of the Study:
- To investigate the impact of guest molecules (water and ethanol) on the structural and spin-crossover properties of a 2-D Hofmann-like framework, [Fe(furpy)2Pd(CN)4]·nG.
- To elucidate the relationship between framework symmetry, guest-framework interactions, and the spin-state transition mechanism.
- To understand how subtle structural modifications affect the cooperativity and transition temperature of SCO events.
Main Methods:
- Variable-temperature magnetic susceptibility measurements to probe spin-crossover transitions.
- Single-crystal X-ray diffraction analyses to determine the crystallographic structures of the guest-framework compounds.
- Detailed structure-function analyses to correlate structural features with magnetic behavior.
Main Results:
- The framework [Fe(furpy)2Pd(CN)4]·nG exhibits different SCO behaviors depending on the guest molecules: asymmetric multistep SCO for the ethanol-water solvate (A·H2O,Et) and abrupt single-step SCO for the water solvate (A·H2O).
- The water solvate (A·H2O) shows an upshift in transition temperature of approximately 75 K compared to the ethanol-water solvate.
- Single-crystal studies revealed distinct symmetries and FeII coordination environments: primitive orthorhombic with a unique FeII center for A·H2O,Et, and triclinic with two inequivalent FeII centers for A·H2O, indicating guest-induced structural changes influencing SCO cooperativity.
Conclusions:
- Guest molecule inclusion, specifically ethanol, plays a crucial role in modulating the spin-crossover mechanism and transition temperatures in 2-D Hofmann-like frameworks.
- The structural differences arising from guest modification directly impact the cooperativity of spin transitions, leading to distinct multistep versus single-step SCO behaviors.
- This study highlights the potential of guest engineering in designing functional molecular materials with tailored magnetic properties.
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