Investigations of the photophysical properties of sunscreen active ingredients

CHED 997

Rachel E. Lipner,, Brandi Michelle Baughman,, and Sarah J. Schmidtke, Department of Chemistry, The College of Wooster, 943 College Mall, Wooster, OH 44691
This research investigates the photophysical properties of two UV absorbers found in sunscreens, oxybenzone and dioxybenzone through experimental and computational analysis. This project examines how these two compounds are affected by different solvent environments and how these changes influence their spectral properties, in terms of stability and photodegradation after UV radiation, intramolecular and intermolecular bonding, and potential proton transfer. Research indicates dioxybenzone is affected by changes in solvent more so than oxybenzone. Monitoring the spectral transitions after periods of exposure to UV radiation by means of natural sunlight and a UV lamp show that photodegradation occurs within five hours. A dramatic decrease in absorbance is observed after the first 15 minutes of natural sunlight exposure for both compounds. Computational studies reveal that the B3PW91 and B3LYP levels of theory when paired with the Midi! basis set result in similar bond lengths, dihedral angles, bond angles, energies, and excitation energies.