Unraveling the Molecular Structure of Zeolite–Octyl Methoxycinnamate Hybrid UV Filters: A Combined Spectroscopic and Computational Approach

In this contribution, we tried to shed light on the molecular structure of octyl methoxycinnamate (octinoxate, OMC) adsorbed in NaX zeolite, which represents a promising hybrid UV filter system. The combination of infrared spectroscopy and density functional theory modeling was crucial to identify all the complex host-guest interactions and to unveil that, although slightly thermodynamically unfavored, OMC is dominantly present in the trans-form inside the NaX framework. We also showed that the interaction between the zeolite Na cations and the OMC molecule is the key feature that determines the stability and efficacy of these hybrid UV filters. These findings confirm that cationic zeolites are promising materials for the encapsulation of UV filters to decrease their negative impact on the environment and their photochemical instability.