Soft porous crystals: flexible MOFs as a new class of adaptive materials

Soft porous crystals (SPCs), particularly soft metal–organic frameworks (MOFs), represent a promising class of crystalline porous materials distinguished by their structural flexibility, dynamic behavior, and strong responsiveness to external stimuli. These features set them apart from conventional rigid materials and make them highly attractive for advanced technological applications. Despite extensive research on MOFs overall, soft MOFs remain relatively underexplored, and further investigation into their potential is essential for advancing materials science and enabling next-generation technologies. Although both SPCs and their rigid counterparts face common challenges in long-term operational stability (thermodynamic, chemical resistance, and mechanical durability) and large-scale high-quality production, the adaptive properties of SPCs—such as energy efficiency, high selectivity, and high capture efficiency—open up new frontiers for industrial production and real-world applications. In this perspective, to gain a comprehensive understanding of their promising applications, the research landscape is divided based on dosage usage regarding scaling softness, covering both (ⅰ) moderate and high-dose applications (storage and separation, catalysis, and energy storage) and (ⅱ) trace or low-dose applications (electronic devices, biomedicine, and nuclear industry), and summarize the key technological fields within each category. It should be noted that high-quality SPCs can typically be obtained at low doses. However, at high doses, the increased presence of defects or disorder may lead to non-uniform structural transformations that propagate through the material. This behavior must be carefully considered in practical applications. Ultimately, an insightful outlook on the promising prospects of SPCs is provided.