A Reevaluation of the Photolytic Properties of 2‐Hydroxybenzophenone‐Based UV Sunscreens: Are Chemical Sunscreens Inoffensive?

MT Ignasiak, C Houée‐Levin, G Kciuk… - …, 2015 - Wiley Online Library
MT Ignasiak, C Houée‐Levin, G Kciuk, B Marciniak, T Pedzinski
ChemPhysChem, 2015Wiley Online Library
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× 1012 s− 1. The ESIPT yields a keto conformer that
undergoes a fast, picosecond internal conversion decay. However, a photodegradative …
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=2×1012 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.
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