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A Reevaluation of the Photolytic Properties of 2‐Hydroxybenzophenone‐Based UV Sunscreens: Are Chemical Sunscreens Inoffensive?
Author(s) -
Ignasiak Marta T.,
HouéeLevin Chantal,
Kciuk Gabriel,
Marciniak Bronislaw,
Pedzinski Tomasz
Publication year - 2015
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201402703
Subject(s) - photochemistry , chemistry , picosecond , intramolecular force , radical , excited state , reactivity (psychology) , reaction rate constant , organic chemistry , kinetics , laser , physics , alternative medicine , pathology , quantum mechanics , nuclear physics , optics , medicine
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 HO 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.