Regulation of Multistep Spin Crossover Across Multiple Stimuli in a 2-D Framework Material
Résumé
We investigate the effects of a broad array of external stimuli on the structural, spin-crossover (SCO) properties and nature of the elastic interaction within the 2-D Hofmann framework material [Fe(cintrz)2Pd(CN)4]•guest (cintrz = N-cinnamalidene 4-amino-1,2,4-triazole; A•guest; guest = 3H2O, 2H2O & ∅). This framework exhibits a delicate balance between ferro-and antiferro-elastic interaction characters; we show that manipulation of the pore contents across guest = 3H2O, 2H2O and ∅ can be exploited to regulate this balance. In A•3H2O, dominant antiferroelastic interaction character between neighboring Fe II sites sees the low temperature persistence of the mixed spin-state species {HS-LS}, for {Fe1-Fe2} (HS = high spin, LS = low spin). Elastic interaction strain is responsible for stabilizing the {HS-LS} state and can be overcome by three mechanisms: (1) partial (2H2O) or complete (∅) guest removal, (2) irradiation via the reverse-LIESST effect ( = 830 nm; light-induced excited spin-state trapping) and (3) the application of external hydrostatic pressure. Combining experimental data with elastic models presents a clear interpretation that while guest molecules cause a negative chemical pressure, they also have consequences for the elastic interactions between metals beyond the simple chemical pressure picture typically proposed.
Domaines
Matériaux
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2022-051.pdf (1.55 Mo)
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