Dynamic Heating-Induced Structural Disorder and Its Impact on Magnetism in a Fe-Based Zeolitic Imidazolate Framework

Modulating the degree of structural disorder in metal–organic frameworks (MOFs) offers a promising strategy for tuning their physical and chemical properties. Structural disorder in MOFs can be created by various means, e.g., mechanical treatment or melting. Here, we show that structural disorder can be induced in an iron-based zeolitic imidazolate framework (denoted as Fe-ZIF) upon dynamic heating. The onset temperature of such structural disorder in Fe-ZIF is lower than its melting point. Small- and wide-angle X-ray scattering, together with high-energy synchrotron X-ray diffraction, revealed that structural disorder primarily evolves at the medium- and long-range scales, while the short-range order remains largely preserved. The distortion of medium-range structural domains, particularly the [Fe4Im8] clusters, led to the loss of long-range atomic periodicity in Fe-ZIF. Moreover, magnetic measurements demonstrate that the sample with a higher degree of medium-range structural disorder exhibited a lower spin freezing temperature. Thus, our work established a viable strategy for tailoring structural disorder in MOFs, enabling precise modulation of their magnetic functions.