Li Yi-Dan, Ma Lu-Fang, Yang Guo-Ping, Wang Yao-Yu
Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, Xi'an Key Laboratory of Functional Supramolecular Structure and Materials, College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, P. R. China.
College of Chemistry and Chemical Engineering, Henan Key Laboratory of Function-Oriented Porous Materials, Luoyang Normal University, Luoyang, 471934, P. R. China.
Angew Chem Int Ed Engl. 2025 Mar 10;64(11):e202421744. doi: 10.1002/anie.202421744. Epub 2025 Feb 3.
The encapsulation of viologen derivatives in metal-organic frameworks (MOFs) to construct host-guest materials has been widely discussed owing to their distinctive spatial arrangement and physical/chemical properties. Herein, three new photochromic MOFs (NWM-1-3) have been successfully synthesized by 1,1,2,2-Tetra(4-carboxylphenyl)ethylene (HTCPE) ligand as well as three different viologen derivatives based on host-guest strategy. Remarkably, NWM-1-3 exhibit a notable reversible photochromism change from yellow to green under 365 nm UV irradiation. The distance between the electron-deficient N atom in the viologens and the electron-rich carboxylate oxygens satisfies the electron transfer (ET) pathway, and thus ET occurs upon irradiation, producing intermolecular viologen radicals. NWM-1 is able to produce colored responses to different volatile amines by ET and can be recognizable to the naked eye. Differential pulse voltammetry (DPV) analysis and comparative experiments have demonstrated that the host-guest strategy significantly enhances the electron-accepting ability of viologens, thereby achieving superior amine sensing performance. NWM-2 and 3 have been realized in various applications, such as security code, fingerprint, and QR codes for anticounterfeiting. This work provides new host-guest strategy for designing highly sensitive photochromic materials and color-tunable luminescent materials, advancing the development of assembled photochromic materials closer to commercialization.
由于其独特的空间排列和物理/化学性质，将紫精衍生物封装在金属有机框架（MOF）中以构建主客体材料已得到广泛讨论。在此，通过1,1,2,2-四（4-羧基苯基）乙烯（HTCPE）配体以及基于主客体策略的三种不同紫精衍生物，成功合成了三种新型光致变色MOF（NWM-1-3）。值得注意的是，NWM-1-3在365 nm紫外光照射下表现出从黄色到绿色的显著可逆光致变色变化。紫精中缺电子的N原子与富电子的羧酸根氧之间的距离满足电子转移（ET）途径，因此在光照下会发生ET，产生分子间紫精自由基。NWM-1能够通过ET对不同的挥发性胺产生颜色响应，并且肉眼可识别。差分脉冲伏安法（DPV）分析和对比实验表明，主客体策略显著增强了紫精的电子接受能力，从而实现了优异的胺传感性能。NWM-2和3已在各种应用中得以实现，如用于防伪的安全码、指纹和二维码。这项工作为设计高灵敏度光致变色材料和颜色可调发光材料提供了新的主客体策略，推动了组装光致变色材料的发展更接近商业化。
