Recent Advances in Spiropyran‐Based Solid‐State Photochromic Materials: From Molecular Design to Functional Applications

Abstract Photochromic compound spiropyran stands out due to its exceptional optical properties and thermal stability, playing a pivotal role in photochromic research. Although extensive studies focus on its photochromic behavior in solution, the solid‐state photochromism of spiropyran remains underexplored, despite its critical importance for practical applications such as optical data storage, anti‐counterfeiting, and bioimaging. These advantages make spiropyran‐based materials highly attractive; they are particularly well‐suited for use in anti‐counterfeiting inks and super‐resolution imaging agents. This review systematically examines recent advances in molecular engineering strategies to overcome the inherent limitations of spiropyran‐based solid‐state systems, particularly addressing challenges in molecular packing constraints, photoisomerization efficiency, and environmental stability. Three pivotal dimensions are highlighted: 1) mechanistic insights into intermolecular interactions on photochromic behaviors, 2) innovative structural design approaches including bulky substitution, host‐guest complexation, and polymer matrix integration, and 3) special emphasis is placed on the mesoporous framework materials encapsulating spiropyran, which enable unprecedented spatiotemporal control in solid‐state environments. Here, the persistent challenges limiting the development of solid‐state photochromic materials based on spiropyran photo‐switches are addressed and innovative design principles for high‐efficiency photochromic systems are presented. This review establishes a systematic framework for enhancing the solid‐state photochromism of spiropyran derivatives and facilitating their practical applications.