title: A reevaluation of the photolytic properties of 2-hydroxybenzophenone-based UV sunscreens: are chemical sunscreens inoffensive?
abstract: The excited states of a set of popular sunscreen agents (2-hydroxybenzophenone, oxybenzone, and sulisobenzone) are studied by using femto- and nanosecond time-resolved spectroscopy. Upon excitation, the compounds undergo an ultrafast excited-state intramolecular proton transfer (ESIPT) reaction as the major energy-wasting process and the rate constant of this reaction is k=2×10(12) s(-1) . The ESIPT yields a keto conformer that undergoes a fast, picosecond internal conversion decay. However, a photodegradative pathway is a monophotonic HO bond breakage that subsequently leads to trace yields of phenoxyl radicals. Because potentially harmful phenoxyl radicals are formed upon irradiation of sunscreen agents, care should be taken about their reactivity towards biologically relevant compounds.
authors.affiliation: Faculty of Chemistry, Adam Mickiewicz University, 89b Umultowska Str., 61-614 Poznan (Poland); Laboratoire de Chimie-Physique, Université Paris-Sud, CNRS UMR 8000, 91405 Orsay Cedex, (France).
authors.forename: Marta T
authors.initials: MT
authors.lastname: Ignasiak
authors.forename: Chantal
authors.initials: C
authors.lastname: Houée-Levin
authors.forename: Gabriel
authors.initials: G
authors.lastname: Kciuk
authors.forename: Bronislaw
authors.initials: B
authors.lastname: Marciniak
authors.forename: Tomasz
authors.initials: T
authors.lastname: Pedzinski
mesh_terms: D001577:Benzophenones / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry; D010782:Photolysis; D013050:Spectrometry, Fluorescence; D013473:Sunscreening Agents / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D001577:Benzophenones; D010636:Phenols; D013473:Sunscreening Agents; C042329:phenoxy radical; C562127:ortho-hydroxybenzophenone
keywords: benzophenones; excited-state intramolecular proton transfer (ESIPT); photochemistry; radicals; sunscreens