Work

Emergent Spin‐Glass Behavior in an Iron(II)‐Based Metal–Organic Framework Glass

Year: 2025

Type: article

Abstract: Metal–organic framework (MOF) glasses combine the structural tunability of crystalline MOFs with the processability of amorphous materials, offering exciting opportunities for functional hybrid materials. Here, a one‐pot, solvent‐free synthesis is reported of an Fe 2+ ‐based MOF glass, g Fe‐ t Bubipy , with the composition [Fe 2 (im) 3.12 (bim) 0.88 ( t Bubipy) 0.11 ]·[Fe(Cp) 2 ] 0.09 (im − = imidazolate, bim − = benzimidazolate, t Bubipy = 4,4′‐di‐ tert ‐butyl‐2,2′‐bipyridine, Cp − = cyclopentadienyl anion). This material forms a continuous random network structure of four‐connected tetrahedral and octahedral Fe 2+ nodes and exhibits an exceptionally low glass transition temperature ( T g = 87 °C). Despite its amorphous nature and complex composition, g Fe‐ t Bubipy exhibits a high degree of local structural order that enables strong antiferromagnetic exchange interactions between Fe 2+ centers. Remarkably, it exhibits clear signatures of spin‐glass behavior, with a well‐defined magnetic freezing transition ≈14 K. This combination of a MOF glass exhibiting a distinct glass transition with spin‐glass magnetism arising from topological disorder and frustrated, short‐range magnetic interactions represent a significant advance. This discovery underscores the transformative potential of MOF glasses as a versatile platform for exploring the interplay between structural disorder and cooperative magnetic phenomena in hybrid materials.

Source: Advanced Functional Materials

DOI: 10.1002/adfm.202517854