A Study of the Photochemical Properties of Some Cinnamate Sunscreens by Steady State and Laser Flash Photolysis

Abstract

The E⇄ Z photoisomerization of 4′‐methoxycinnamates, used as sunscreens in cosmetics, has been studied by steady state and laser flash photolysis, in aqueous and organic solutions. Photoisomerization quantum yields are found to be fairly high (˜0.5‐1), although no intermediate is detected upon laser flash photolysis. Cinnamates are not photodynamic sensitizers but are able to quench the 8‐methoxy‐psoralen and 5‐methoxypsoralen triplets which produces E → Z isomerization.

2‐Acetylindan‐1,3‐dione and its Cu2+ and Zn2+ complexes as promising sunscreen agents

“…5). This result is in agreement with available data in the literature [25–27]. According to [25], after irradiation, OMC shows moderate degradation (18.7%) in non‐polar solvents (mineral oil and iso propyl miristate), whereas in polar hydroalcoholic solvent (ethanol/water), 39% degradation of the molecule is observed.…”

Photostability assessment of sunscreens. Benzylidene camphor and dibenzoylmethane derivatives

“…Detailed study of the E % Z isomerization of some benzylidene camphor derivatives has been published by the authors (1,2); the same type of study with a cinnamic acid derivative has been reported (3). Similarly, several works have been devoted to the study of p-aminobenzoic acid photodecomposition (4) and one of its N,N-disubstituted esters (5,6).…”

Photolysis of the organic UV filter, avobenzone, combined with octyl methoxycinnamate by nano-TiO2 composites

“…However, transfer from one excited triplet state to another is possible, provided the energy levels are suitable (the triplet state energies of avobenzone and OMC are 250 kJ/mol and 239 kJ/mol, respectively [6]). Indeed, in a number of studies, OMC has been regarded as a relatively photostable compound [7][8][9]. It has been reported that triplet-triplet energy transfer is not only the mechanism for the photostabilization of avobenzone by octocrylene, but also the mechanism for the photodegradation of avobenzone by OMC.…”