Light-Induced Self-Healing Behaviour in Photosalient MOF

Achieving self-healing in the photosalient crystals without compromising structural integrity remains a fundamental challenge. So far, self-healing has relied predominantly on a single mechanistic pathway, and systems that integrate multiple cooperative chemical processes are exceedingly rare. Here, we introduce a molecular design strategy that couples the photosalient property with an autogenous self-healing by embedding dynamic covalent disulfide (S–S) linkages into a photoreactive MOF. Using 2-mercaptobenzoic acid, which undergoes in situ oxidation to form S–S bonds during crystallisation, we obtained the 2D MOF. The crystal undergoes cracking followed by a pronounced photosalient motion under UV irradiation. Continued irradiation induces nearly 90% self-healing, acting as a self-healing optical window by restoring optical transparency and single-crystal integrity, as verified by multimodal microscopic techniques and AFM. Comprehensive analysis using single-crystal X-ray diffraction (SXRD), and spectroscopy collectively elucidate the dual mechanisms, such as solid-state [2 + 2] cycloaddition and dynamic covalent chemistry (DCC) (S–S), respectively responsible for the photosalient effect and subsequent autogenous self-healing. This work establishes the first autogenous self-healing in a photosalient MOF with dual chemical phenomenon and demonstrates a rare 2D to 3D transformation operating through an “ SC-crack-heal-SC ” mechanism. This approach opens new avenues for soft robotics, adaptive optics, energy harvesting devices, and resilient next-generation functional materials.