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 Fe2+-based MOF glass, gFe-tBubipy, with the composition Fe2(im)3.12(bim)0.88(tBubipy)0.11·Fe(Cp)20.09 (im− = imidazolate, bim− = benzimidazolate, tBubipy = 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 Fe2+ nodes and exhibits an exceptionally low glass transition temperature (Tg = 87 °C). Despite its amorphous nature and complex composition, gFe-tBubipy exhibits a high degree of local structural order that enables strong antiferromagnetic exchange interactions between Fe2+ 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.
DAS et al. (Wed,) studied this question.