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Correlating Mechanical Sensitivity with Spin Transition in the Explosive Spin Crossover Complex [Fe(Htrz)3][ClO4]2
Thuy-Ai D Nguyen, Jacqueline M Veauthier, Gary F Angles-Tamayo
1Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
Journal of the American Chemical Society
|February 14, 2020
Summary
This study reveals that explosive spin crossover complexes can have switchable impact sensitivity. The sensitivity of [Fe(Htrz)3][ClO4]2 changes with its spin transition, offering new possibilities for smart materials.
Area of Science:
- Materials Science
- Chemistry
- Physics
Background:
- Spin crossover (SCO) complexes exhibit changes in physical properties during spin transitions.
- These transitions can influence the sensitivity of energetic materials, suggesting potential for switchable explosives.
Purpose of the Study:
- To investigate the relationship between spin transition and mechanical impact sensitivity in an explosive SCO compound.
- To develop and utilize a variable temperature impact test to assess sensitivity changes.
Main Methods:
- Synthesized and characterized [Fe(Htrz)3][ClO4]2 (1) and a non-SCO Ni analog (2).
- Employed a variable temperature impact test to measure impact sensitivity of compound 1 in different spin states (low spin, high spin, mixed).
- Utilized density functional theory (DFT) to predict structural changes associated with spin transition.
Main Results:
- A direct correlation between impact sensitivity and spin transition was observed for compound 1.
- Impact sensitivity was lower in the low spin state and increased upon transition to the high spin state.
- DFT calculations predicted structural changes that correlate with observed sensitivity variations.
Conclusions:
- Demonstrates the first explosive spin crossover compound (ExSCO) with switchable impact sensitivity.
- The ExSCO exhibits a fully reversible internal switching mechanism for sensitivity modulation.
- This work opens avenues for developing new classes of sensitivity-switchable energetic materials.
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