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

Manan Ahmed; Katrina A Zenere; Natasha F Sciortino; Kasun S A Arachchige; Gemma F Turner; Jace Cruddas; Carol Hua; Jason R Price; Jack K Clegg; Francisco Javier Valverde-Muñoz; Jose A Real; Guillaume Chastanet; Stephen A Moggach; Cameron J Kepert; Benjamin J Powell; Suzanne M Neville

doi:10.1021/acs.inorgchem.2c00530

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

Inorg Chem. 2022 May 2;61(17):6641-6649. doi: 10.1021/acs.inorgchem.2c00530. Epub 2022 Apr 20.

Authors

Manan Ahmed¹, Katrina A Zenere², Natasha F Sciortino², Kasun S A Arachchige³, Gemma F Turner⁴, Jace Cruddas⁵, Carol Hua⁶, Jason R Price⁷, Jack K Clegg³, Francisco Javier Valverde-Muñoz⁸, Jose A Real⁸, Guillaume Chastanet⁹, Stephen A Moggach⁴, Cameron J Kepert², Benjamin J Powell⁵, Suzanne M Neville¹

Affiliations

¹ The School of Chemistry, UNSW Sydney, Sydney 2052, New South Wales, Australia.
² The School of Chemistry, The University of Sydney, Sydney 2006, New South Wales, Australia.
³ School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia 4072, Queensland, Australia.
⁴ School of Molecular Sciences, The University of Western Australia, Perth 6009, Western Australia, Australia.
⁵ School of Mathematics and Physics, The University of Queensland, St Lucia 4072, Queensland, Australia.
⁶ School of Chemistry, The University of Melbourne, Parkville 3010, Victoria, Australia.
⁷ The Australian Synchrotron, 800 Blackburn Road, Clayton 3168, Victoria, Australia.
⁸ Insitut de Ciencia Molecular, Department de Quimica Inorganica, Universitat de Valéncia, Patterna 46980, Valéncia, Spain.
⁹ University of Bordeaux, CNRS, Bordeaux-INP, ICMCB, UMR 5026, Pessac F-33600, France.

PMID: 35442030
DOI: 10.1021/acs.inorgchem.2c00530

Abstract

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 two-dimensional Hofmann framework material [Fe(cintrz)₂Pd(CN)₄]·guest (cintrz = N-cinnamalidene 4-amino-1,2,4-triazole; A·guest; guest = 3H₂O, 2H₂O, and Ø). This framework exhibits a delicate balance between ferro- and antiferro-elastic interaction characters; we show that manipulation of the pore contents across guests = 3H₂O, 2H₂O, and Ø can be exploited to regulate this balance. In A·3H₂O, the 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 (Ø) guest removal, (2) irradiation via the reverse light-induced excited spin-state trapping (LIESST) effect (λ = 830 nm), 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.