Borchers Tristan H, Topić Filip, Arhangelskis Mihails, Vainauskas Jogirdas, Titi Hatem M, Bushuyev Oleksandr S, Barrett Christopher J, Friščić Tomislav
Department of Chemistry, McGill University, Montreal H3A 0B8, Canada.
School of Chemistry, University of Birmingham, Birmingham B15 2TT, United Kingdom.
J Am Chem Soc. 2023 Nov 4;145(45):24636-47. doi: 10.1021/jacs.3c07060.
Cocrystallization of a -azobenzene dye with volatile molecules, such as pyrazine and dioxane, leads to materials that exhibit at least three different light-intensity-dependent responses upon irradiation with low-power visible light. The halogen-bond-driven assembly of the dye -(-iodoperfluorophenyl)azobenzene with volatile halogen bond acceptors produces cocrystals whose light-induced behavior varies significantly depending on the intensity of the light applied. Low-intensity (<1 mW·cm) light irradiation leads to a color change associated with low levels of → isomerization. Irradiation at higher intensities (150 mW·mm) produces photomechanical bending, caused by more extensive isomerization of the dye. At still higher irradiation intensities (2.25 W·mm) the cocrystals undergo cold photocarving; i.e., they can be cut and written on with micrometer precision using laser light without a major thermal effect. Real-time Raman spectroscopy shows that this novel photochemical behavior differs from what would be expected from thermal energy input alone. Overall, this work introduces a rational blueprint, based on supramolecular chemistry in the solid state, for new types of crystalline light-responsive materials, which not only respond to being exposed to light but also change their response based on the light intensity.
α-偶氮苯染料与挥发性分子（如吡嗪和二氧六环）的共结晶会产生一些材料，这些材料在低功率可见光照射下表现出至少三种不同的光强度依赖性响应。染料-（-碘全氟苯基）偶氮苯与挥发性卤素键受体通过卤素键驱动组装生成共晶体，其光诱导行为会根据所施加光的强度而显著变化。低强度（<1 mW·cm）光照射会导致与低水平的→异构化相关的颜色变化。较高强度（150 mW·mm）照射会产生光机械弯曲，这是由染料更广泛的异构化引起的。在更高的照射强度（2.25 W·mm）下，共晶体会发生冷光雕刻；也就是说，可以使用激光以微米精度对其进行切割和书写，而不会产生重大热效应。实时拉曼光谱表明，这种新型光化学行为不同于仅由热能输入所预期的行为。总体而言，这项工作基于固态超分子化学引入了一种合理的蓝图，用于新型结晶光响应材料，这些材料不仅对光照有响应，还会根据光强度改变其响应。
