Photo-Activated Motion of Layered Hybrids Induced by the High-Order Architecture of Azobenzene Assembly on Niobate Nanosheets and the Microenvironment

A layered nanosheet hybrid composed of niobate nanosheet and polyfluoroalkyl azobenzene derivative (C3F-Azo-C6H) can undergo three-dimensional morphology change upon photo-irradiations. The unique photo-activated motion is based on the interlayer distance change and nanosheet sliding induced by the photo-isomerization of C3F-Azo-C6H which is presumably caused by the subsequent changes of the nanostructure in the hybrid. However, the mechanism of the morphological change at a molecular level has not yet been fully understood. The nanostructure and its delicate change in the layered hybrid should be closely related to the mechanism. Here, the nanostructure has been investigated in detail by X-ray diffraction, thermogravimetric/differential thermal analysis, and UV–vis and IR spectroscopy to get deeper insights into the mechanism of the photo-activated motion. Based on the intercalation amount, the molecular size, the clearance space, and the tilting angles, C3F-Azo-C6Hs are considered to align on the nanosheet and form an interdigitated bilayer structure in their terminal alkyl chains. The intercalated C3F-Azo-C6Hs also form a two-dimensional network having intermolecular hydrogen bonding among their amide groups and π–π interaction of azobenzene. Furthermore, it was revealed that the terminal alkyl chains located in the center of the bilayer are swung by the swayback motion of the isomerized azobenzene to induce the morphology change. The high-order architecture formed on the nanosheets should be a key factor in inducing the cooperative reaction and conformational change of C3F-Azo-C6H on the niobate nanosheet microenvironment.