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A spin transition molecular material with a wide bistability domain
Yann Garcia1, Jacques Moscovici, Alain Michalowicz
1Institut für Anorganische Chemie und Analytische Chemie, Universität Mainz, Staudingerweg, Germany. garcia@chim.ucl.ac.be
Chemistry (Weinheim an Der Bergstrasse, Germany)
|December 20, 2002
Summary
This study synthesized a new iron(II) compound exhibiting a spin transition with an unprecedented 50 K hysteresis loop. The material
Area of Science:
- Coordination Chemistry
- Materials Science
- Solid-State Physics
Background:
- Spin crossover (SCO) materials are of interest for molecular switches and sensors.
- Iron(II) complexes with 1,2,4-triazole ligands are known to exhibit SCO behavior.
- Wide thermal hysteresis is desirable for memory device applications.
Purpose of the Study:
- To synthesize and characterize a novel iron(II) SCO complex.
- To investigate the spin transition properties and thermal hysteresis.
- To elucidate the structural and cooperative effects influencing the spin transition.
Main Methods:
- Synthesis of [Fe(hyptrz)3](4-chloro-3-nitrophenylsulfonate)2·2H2O.
- Magnetic susceptibility measurements, calorimetry, Mössbauer, optical, and EXAFS spectroscopy.
- Temperature-dependent EXAFS studies for structural analysis.
Main Results:
- The synthesized compound exhibits a spin transition below room temperature.
- An exceptionally wide thermal hysteresis loop of approximately 50 K was observed.
- EXAFS spectroscopy revealed the structural characteristics in both spin states and confirmed linear 1,2,4-triazole chains.
Conclusions:
- The novel iron(II) complex demonstrates a record-breaking hysteresis width for FeII-1,2,4-triazole SCO materials.
- The findings highlight the potential of such materials for applications requiring wide thermal hysteresis.
- The study provides insights into the cooperativity and structural factors governing spin transitions in these systems.