Octyl methoxycinnamate (2-ethylhexyl 4-methoxycinnamate, OMC) is a commercial sunscreen known as octinoxate with excellent UVB filter properties. However, it is known to undergo a series of photodegradation processes that decrease its effectiveness as a UVB filter. In particular, the trans (E) form—which is considered so far as the most stable isomer—converts to the cis (Z) form under the effect of light. In this work, by using post-Hartree–Fock approaches [CCSD, CCSD(t), and CCSD + T(CCSD)] on ground state OMC geometries optimized at the MP2 level, we show that the cis and trans forms of the gas-phase OMC molecule have comparable stability. Test calculations on the same structures with a series of dispersion-corrected density functional theory-based approaches including the B2PLYP double hybrid predict the trans structures to be energetically favored, missing the subtle stabilization of cis-OMC. Our results suggest that the cis form is stabilized by intra-molecular dispersion interactions, leading to a folded more compact structure than the trans isomer.

A post-HF approach to the sunscreen octyl methoxycinnamate

Fois, Ettore
Primo
;
Oriani, Mario
Secondo
;
Tabacchi, Gloria
Ultimo
2021-01-01

Abstract

Octyl methoxycinnamate (2-ethylhexyl 4-methoxycinnamate, OMC) is a commercial sunscreen known as octinoxate with excellent UVB filter properties. However, it is known to undergo a series of photodegradation processes that decrease its effectiveness as a UVB filter. In particular, the trans (E) form—which is considered so far as the most stable isomer—converts to the cis (Z) form under the effect of light. In this work, by using post-Hartree–Fock approaches [CCSD, CCSD(t), and CCSD + T(CCSD)] on ground state OMC geometries optimized at the MP2 level, we show that the cis and trans forms of the gas-phase OMC molecule have comparable stability. Test calculations on the same structures with a series of dispersion-corrected density functional theory-based approaches including the B2PLYP double hybrid predict the trans structures to be energetically favored, missing the subtle stabilization of cis-OMC. Our results suggest that the cis form is stabilized by intra-molecular dispersion interactions, leading to a folded more compact structure than the trans isomer.
2021
https://doi.org/10.1063/5.0046118
correlated wavefunction methods; post-Hartree-Fock calculations; dispersion interactions; Density Functional Theory; UV filter; octinoxate; double hybrid functional; sunscreen agent
Fois, Ettore; Oriani, Mario; Tabacchi, Gloria
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11383/2111138
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