Preparation of azobenzene-intercalated kaolinite and monitoring of the photoinduced activity

Systems consisting of layered structures and photoactive molecules have been studied extensively. The structures of resulting complexes may be controlled by UV–Vis radiation, which subsequently affects their materials properties. This study describes a synthesis route for obtaining a photoresponsive kaolinite intercalation compound. The material was prepared by co-intercalating azobenzene and benzylalkylammonium chlorides into a methoxy form of kaolinite. The resultant materials possessed large basal spacing values in the range of 45–55 Å. The UV–Vis and Fourier-transform infrared spectroscopy analyses confirmed the reversible photoisomerization of azobenzene upon exposure to UV and Vis radiation. This phenomenon was significantly influenced by the type and amount of co-intercalated molecules. Upon multiple trans–cis conversions, the azobenzene partially evaporated. For the first time, a kaolinite-based material was prepared that exhibited photochromic behaviour upon UV and Vis irradiation.