Guest‐Switchable Multi‐Step Spin Transitions in an Amine‐Functionalized Metal–Organic Framework

Abstract

Abstract Materials with hysteretic multi‐step spin‐crossover (SCO) have potential application in high‐order data storage. Here, an unprecedented hysteretic four‐step SCO behavior with the sequence of LS↔HS 0.25 LS 0.75 ↔HS 0.5 LS 0.5 ↔ HS 0.75 LS 0.25 ↔HS is found in a three‐dimensional (3D) Hofmann‐type metal–organic framework (MOF), which is evidenced by magnetic, differential scanning calorimetry, and crystal data. Further experiments involving guest exchange leads to the first reversible modulation of four‐, two‐, and one‐stepped SCO behaviors, which provides a new strategy for developing multi‐step SCO materials.