AbstractLight-driven atropisomeric polymers containing azo and binaphthyl units with a conjugated structure were designed and synthesized. The polymers exhibit a glass transition temperature higher than 75 °C with thermal stability above 280 °C and form uniform and smooth thin films without grain boundaries. The trans-cis isomerization is efficiently reversible upon alternating photoirradiation with UV and visible light or with heat. The photoisomerization of the chiral polymer results in photomodulation of the ellipticity and optical rotation ($$[\alpha ]_{\mathrm{D}}^{25}$$[α]D25), owing to a chiroptical switching behavior. The maximum changes in the dihedral angle and $$[\alpha ]_{\mathrm{D}}^{25}$$[α]D25 are 21% and 700°, respectively, from the initial state owing to a photoinduced molecular twisting motion of the binaphthyl moiety. The polymer also displays photoswitchable fluorescence with a maximum at 409 nm. A photoinduced change in the refractive index of the formed film is also observed after irradiation with linearly polarized light at 532 nm according to the anisotropic molecular orientation. These results suggest that atropisomeric polymers are potential candidates for light-driven chiroptical switches.Photoinduced molecular switches were achieved by atropisomeric polymers containing conjugated structures of azo and binaphthyl units. trans-cis Photoisomerization of the azo unit led to molecular twisting motion of the binaphthyl unit, yielding chiroptical switching in a neat film. The atropisomeric polymers also displayed photoswitchable fluorescence by repeated irradiation of UV and visible light. Irradiation of the neat film with linearly polarized light caused selective excitation of the atropisomeric polymer, leading to anisotropic molecular orientation.

中文翻译：

---

侧链中含有偶氮联萘基的阻转异构聚合物的光驱动分子转换

摘要 设计并合成了具有共轭结构的偶氮和联萘单元的光驱动阻转异构聚合物。该聚合物的玻璃化转变温度高于 75°C，热稳定性高于 280°C，并形成均匀光滑的无晶界薄膜。在用紫外线和可见光或用热交替光照射后，反式-顺式异构化是有效可逆的。由于手性转换行为，手性聚合物的光异构化导致椭圆率和旋光度（$$[\alpha]_{\mathrm{D}}^{25}$$[α]D25）的光调制。由于光诱导分子的作用，二面角和 $$[\alpha ]_{\mathrm{D}}^{25}$$[α]D25 的最大变化分别为 21% 和 700°。联萘部分的扭转运动。该聚合物还显示出最大波长为 409 nm 的光可切换荧光。根据各向异性分子取向，在用 532 nm 的线偏振光照射后，还观察到形成的薄膜的折射率发生光致变化。这些结果表明阻转异构聚合物是光驱动手性光学开关的潜在候选者。光致分子开关是通过含有偶氮和联萘单元共轭结构的阻转异构聚合物实现的。偶氮单元的反式-顺式光异构化导致联萘单元的分子扭曲运动，从而在纯薄膜中产生手性转换。阻转异构聚合物还通过紫外线和可见光的重复照射显示出可光控荧光。