Regulation of Multistep Spin Crossover Across Multiple Stimuli in a 2-D Framework Material

Manan Ahmed (1) , Katrina Zenere (2) , Natasha Sciortino (2) , Kasun Arachchige (3) , Gemma Turner (4) , Jace Cruddas (5) , Carol Hua (6) , Jason Price (7) , Jack Clegg (3) , Francisco Valverde-Muñoz (8) , Jose Real (8) , Guillaume Chastanet (9) , Stephen Moggach (4) , Cameron Kepert (2) , Benjamin Powell (5) , Suzanne Neville (1)

1 UNSW School of Chemistry [Sydney]
2 School of Chemistry, The University of Sydney
3 School of Chemistry & Molecular Biosciences
4 School of Molecular Sciences
5 School of Mathematics and Physics [Brisbane]
6 School of Chemistry [Melbourne]
7 Australian Synchrotron [Clayton]
8 Insitut de Ciencia Molecular
9 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

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

Manan Ahmed, Katrina Zenere, Natasha Sciortino, Kasun Arachchige, Gemma Turner, et al.. Regulation of Multistep Spin Crossover Across Multiple Stimuli in a 2-D Framework Material. Inorganic Chemistry, 2022, 61 (17), pp.6641-6649. ⟨10.1021/acs.inorgchem.2c00530⟩. ⟨hal-03657569⟩