A DFT Investigation of the Molecular Structure and UV Absorption Spectra of 2-Ethylhexyl 2-Hydroxybenzoate (Octisalate) and <i>Meta</i>-Substituted 2-Ethylhexyl 2-Hydroxybenzoate: Sunscreen Applications

Abstract

2-ethylhexyl 2-hydroxybenzoate (octisalate) is one of organic compounds containing in sunscreen products to absorb ultraviolet radiation. Density Functional Theory (DFT) was used to investigate the molecular structure and the ultraviolet (UV) absorption spectrum of 2-ethylhexyl 2-hydroxybenzoate and meta-substituted 2-ethylhexyl 2-hydroxybenzoate to model the novel sunscreen compounds. The geometry optimizations and frequency calculations were done at B3LYP/6-311++G(d,p) level of theory. The 10 vertical excitation calculations were performed by Time-Dependent Density Functional Theory (TD-DFT) at B3LYP/6-311++G(d,p) level. The solvent effects were taken into account by using the Polarizable Continuum Model (CPCM). It was found that the intramolecular hydrogen bond occurred in the 2-ethylhexyl 2-hydroxybenzoate structure. The UV absorption spectrum in the UVA and UVB regions are π→π* transitions (HOMO→LUMO transitions). The calculated UV absorption spectrum of the 2-ethylhexyl 2-hydroxybenzoate and its derivatives are significantly affected by the substitution groups.