Zeolite/dye hybrid composites: Organization of photoactive azobenzene molecules inside AlPO4-5

Organic/inorganic hybrid materials - like zeolites +dyes - are currently used in strategic areas, from sustainable energy technologies to biomedical sciences. In these systems, photoactive molecules are organized in one-dimensional nanostructures inside the zeolite channels. In this paper we present the results of a study aimed to the synthesis and the structural and spectroscopic characterization of azobenzene/AlPO4-5 hybrid composites, performed by a multi-technique approach based on material synthesis, thermal gravimetric analysis, synchrotron X-ray powder diffraction, UV-VIS and IR spectroscopies. The results indicate that azobenzene molecules are hosted in the 12-membered ring channel of AFI framework and the maximum loading is 0.9 molecules per unit cell. The combination of spectroscopic and diffractometric methods point out that, being AlPO4-5 starting material affected by Brönsted acidity, a consistent portion of the azobenzene molecules is protonated and interact with the framework oxygen atoms.