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Chiral control of spin-crossover dynamics in Fe(II) complexes
Malte Oppermann1, Francesco Zinna2,3, Jérôme Lacour3
1Laboratory of Ultrafast Spectroscopy (LSU) and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, ISIC-FSB, Lausanne, Switzerland. malte.oppermann@epfl.ch.
Researchers stabilized the high-spin state of iron spin-crossover complexes at room temperature by controlling chirality. This breakthrough enhances the kinetic stability of spin-crossover switches for molecular devices.
Area of Science:
- Materials Science
- Chemistry
- Physics
Background:
- Iron-based spin-crossover (SCO) complexes are promising for molecular switches.
- Current limitations include the need for cryogenic temperatures to stabilize the high-spin state.
Purpose of the Study:
- To achieve kinetic stability of the high-spin state in iron SCO complexes at room temperature.
- To explore chiral control for manipulating SCO dynamics.
Main Methods:
- Utilized broadband ultrafast circular dichroism spectroscopy in the deep ultraviolet.
- Employed transient absorption and anisotropy measurements.
- Investigated diastereoselective ion pairing with enantiopure tris(3,4,5,6-tetrachlorobenzene-1,2-diolato-κ2O1,O2)phosphorus(V) (TRISPHAT) anions.
Main Results:
- Demonstrated high-spin-state trapping by controlling the chiral configuration of iron(II) complexes.
- Observed ultrafast changes in optical activity during high-spin state decay, linked to a torsional twisting mode.
- Achieved a fourfold increase in the high-spin state lifetime through diastereoselective ion pairing.
Conclusions:
- Controlling the chiral configuration and associated torsional modes offers a new strategy for manipulating SCO dynamics.
- This approach enables the kinetic stabilization of the high-spin state at ambient temperatures, advancing molecular device applications.
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