Photophysical behavior of sunscreen active ingredients: A combined computational and spectroscopic study

CHED 1429

Brandi Michelle Baughman, bbaughman@wooster.edu and Dr. Sarah Schmidtke. Department of Chemistry, The College of Wooster, Wooster, OH 44691
Oxybenzone and dioxybenzone are organic UV absorbers found in sunscreens, lotions, lip balms, and cosmetics. Studies of solvent effects on spectroscopic properties of these two molecules has been limited to mostly protic polar and aprotic nonpolar solvents to mimic water and oils due to their application in commercial products. Furthermore, theoretical chemistry has played a minimal role in the evaluation of this pair of molecules. This research focuses on theoretical and experimental analysis of the photophysical behavior of oxybenzone and dioxybenzone in a wide range of solvents with varying polarity and hydrogen bonding ability. The molecules were optimized using hybrid density functional theory. ZINDO calculations were used to calculate the vertical excitation energies, as well as properties of electronic states involved in the spectral transitions of the molecules and incorporate solvent effects. The calculated vertical excitations were compared to experimentally found absorbance and fluorescence spectra.