Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, 1-1, Minami-osawa, Hachioji, Tokyo 192-0397, Japan.
Phys Chem Chem Phys. 2019 Oct 9;21(39):21738-21745. doi: 10.1039/c9cp03835c.
A photo-responsive nanoscroll composed of niobate nanosheets and a polyfluoroalkyl azobenzene derivative (C3F-Azo-C6H) is one of the most interesting layered materials because the reversible winding and unwinding motion could be efficiently induced by photo-irradiations. Previously, we have studied a double-walled nanoscroll (DWNS) of niobate that could be synthesized by the intercalation of a cationic polyfluorinated surfactant only into the interlayer I of the layered niobate among the two interlayers, I and II. In this study, we have successfully synthesized another novel photo-responsive single-walled nanoscroll (SWNS) of niobate by a stepwise guest-guest ion-exchange method. All niobate nanosheets that were exfoliated at both interlayers I and II were efficiently converted to nanoscrolls by the intercalation of C3F-Azo-C6H. The synthetic yield has been quantitatively estimated. Though the photo-isomerization reaction of C3F-Azo-C6H was induced in the SWNS, its photo-reactivity was the lowest when compared with those of the nanosheet-stacked film and the DWNS. The photo-reactivity of C3F-Azo-C6H decreased in the order of DWNS > nanosheet-stacked film > SWNS. The different flexibility of the layered miroenvironment might influence the photo-reactivity of C3F-Azo-C6H in the niobate hybrid. The SWNS exhibited a reversible expansion and shrinkage of its interlayer spaces upon photo-irradiation, while the winding and unwinding motion was not observed, contrary to the DWNS. The direction of the expansion and shrinkage of the interlayer of the SWNS was opposite to those of the nanosheet-stacked film and the DWNS. Based on the experimental results, the tilt angle of C3F-Azo-C6H against the nanosheet surface and the matching structures of the top and bottom surfaces of the nanosheet could be the probable key factors that control the photo-reactivity of C3F-Azo-C6H in the layered microenvironment; the morphological changes of the nano hybrids was also discussed.
由铌酸盐纳米片和全氟烷基偶氮苯衍生物（C3F-Azo-C6H）组成的光响应纳米卷是最有趣的层状材料之一，因为其可逆的缠绕和展开运动可以通过光辐照有效地诱导。以前，我们已经研究了一种由阳离子全氟表面活性剂仅插层到层状铌酸盐的两个层之间的层 I 中合成的双壁纳米卷（DWNS）。在这项研究中，我们通过分步客体-客体离子交换方法成功地合成了另一种新型光响应的单壁纳米卷（SWNS）。通过插层 C3F-Azo-C6H，将在两个层 I 和 II 中都剥离的所有铌酸盐纳米片有效地转化为纳米卷。已经定量估计了合成产率。尽管 C3F-Azo-C6H 的光异构化反应在 SWNS 中被诱导，但与纳米片堆积膜和 DWNS 相比，其光反应性最低。C3F-Azo-C6H 的光反应性顺序为 DWNS > 纳米片堆积膜 > SWNS。层状微环境的不同柔韧性可能会影响 C3F-Azo-C6H 在铌酸盐杂化中的光反应性。SWNS 在光照射下表现出层间空间的可逆膨胀和收缩，而没有观察到缠绕和展开运动，与 DWNS 相反。SWNS 的层间空间的膨胀和收缩方向与纳米片堆积膜和 DWNS 的方向相反。根据实验结果，C3F-Azo-C6H 对纳米片表面的倾斜角度以及纳米片上下表面的匹配结构可能是控制 C3F-Azo-C6H 在层状微环境中的光反应性的关键因素；还讨论了纳米杂化物的形态变化。
