Issue 27, 2020

Insights into the photoprotection mechanism of the UV filter homosalate

Abstract

Homosalate (HMS) is a salicylate molecule that is commonly included within commercial sunscreen formulations to provide protection from the adverse effects of ultraviolet (UV) radiation exposure. In the present work, the mechanisms by which HMS provides UV photoprotection are unravelled, using a multi-pronged approach involving a combination of time-resolved ultrafast laser spectroscopy in the gas-phase and in solution, laser-induced fluorescence, steady-state absorption spectroscopy, and computational methods. The unique combination of these techniques allow us to show that the enol tautomer of HMS undergoes ultrafast excited state intramolecular proton transfer (ESIPT) upon photoexcitation in the UVB (290–320 nm) region; once in the keto tautomer, the excess energy is predominantly dissipated non-radiatively. Sharp transitions are observed in the LIF spectrum at close-to-origin excitation energies, which points towards the potential presence of a second conformer that does not undergo ESIPT. These studies demonstrate that, overall, HMS exhibits mostly favourable photophysical characteristics of a UV filter for inclusion in sunscreen formulations.

Graphical abstract: Insights into the photoprotection mechanism of the UV filter homosalate

Supplementary files

Article information

Article type
Paper
Submitted
13 May 2020
Accepted
08 Jun 2020
First published
30 Jun 2020
This article is Open Access
Creative Commons BY-NC license

Phys. Chem. Chem. Phys., 2020,22, 15509-15519

Insights into the photoprotection mechanism of the UV filter homosalate

E. L. Holt, K. M. Krokidi, M. A. P. Turner, P. Mishra, T. S. Zwier, N. d. N. Rodrigues and V. G. Stavros, Phys. Chem. Chem. Phys., 2020, 22, 15509 DOI: 10.1039/D0CP02610G

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