Light‐Driven Crystal Actuation of Fluorinated Acylhydrazones Enabled by [2+2] Photocycloaddition

作者：Jinbo Ouyang, Longping Jiang, Jiayao Li, Feiqiang He, Zhi Gao, Mengmeng Wang, Limin Zhou, Zongbo Xie, Zhiqiang Zhu, Yifu Chen · 发表于：Chemistry - A European Journal · 年份：2025 · DOI：10.1002/chem.202501777 · 被引用次数：1 · 研究领域：Photochromic and Fluorescence Chemistry、Luminescence and Fluorescent Materials、Click Chemistry and Applications

Abstract Crystalline materials with photomechanical responsiveness have garnered significant attention in flexible actuators and micro/nano‐electromechanical systems due to their unique capability to directly convert light into mechanical energy. In this work, four novel fluorinated acylhydrazone compounds were successfully synthesized through direct condensation reactions between 4,4′‐difluorobenzophenone (DFBP) and acylhydrazine compounds, including benzoylhydrazine (BHD), 3‐fluorobenzoylhydrazine (3‐FBHD), isoniazid (IND), and acetylhydrazine (AED). Systematic investigation of their photomechanical responses revealed distinct molecular mechanisms. Experimental results demonstrate that isomeric fluorinated acylhydrazone derivatives (DFBP‐BHD, DFBP‐3‐FBHD, DFBP‐IND) exhibit dynamic photo‐responsive behavior ranging from crack initiation to crystal fragmentation under 365 nm UV irradiation, whereas the hydrazone derivative DFBP‐AED remains inert. This confirms the essential role of [2 + 2] photocycloaddition‐dependent C = N double bonds in photomechanical activity. Comprehensive characterization through DSC, TG, XRD, ¹H/¹ 3 C NMR, and MS elucidated the formation pathways and structural characteristics of photocycloaddition products. Density functional theory calculations revealed that energy disparities between (0 0 1) and (1 0 0) crystallographic planes govern longitudinal fragmentation patterns. This study establishes a “molecular structure‐crystal arrangement‐macroscopic r...