A post-HF approach to the sunscreen octyl methoxycinnamate

Abstract

Octyl methoxycinnamate (OMC) is a commercial sunscreen with excellent UVB filter properties. However, it is known to undergo a series of photodegradation processes that decrease its effectiveness as UVB filter. In particular, the trans (E) form -which is considered so far 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 form of the gas-phase OMC molecule have comparable stability. 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. File list (3) download file view on ChemRxiv Octinoxate_Preprint_Second_Version.pdf (860.69 KiB) download file view on ChemRxiv Optimized_Geometries.zip (4.47 KiB)

Unraveling the Molecular Structure of Zeolite–Octyl Methoxycinnamate Hybrid UV Filters: A Combined Spectroscopic and Computational Approach

“…An initial comparison of the DFT total energies of trans - and cis -OMC showed that the rev-vdW-DF2 functional predicts trans -OMC to be favored over the cis form by about 19 kJ mol –1 . This result is in line with a previous computational study, where similar energy differences were reported for a variety of dispersion-corrected DFT approaches . Therefore, the total energy of trans -OMC was used as the reference value in all adsorption energy calculations.…”

“…For charge balance, 96 Na cations were distributed over four experimentally observed sites (Na2/Na2′, Na3, Na6) 28 in a way that experimental occupancies were matched as closely as possible while at the same time avoiding close cation−cation contacts (see the Supporting Information, section S1 for more details). To study the adsorption of OMC, models of the cis-and trans-forms of OMC were taken from a previous computational study by Fois et al 29 After optimization of the structures of NaX and cis-/ trans-OMC using DFT (see the following subsection), adsorption configurations of both isomers in the pores of NaX were generated using preliminary force field simulations. Loadings of 1 and 4 OMC p.u.c.…”

“…This result is in line with a previous computational study, where similar energy differences were reported for a variety of dispersion-corrected DFT approaches. 29 Therefore, the total energy of trans-OMC was used as the reference value in all adsorption energy calculations. Table 1 reports the DFT adsorption energies obtained for the different NaX/OMC adsorption configurations, ordered according to the adsorption energy.…”

Photochemical Degradation of the UV Filter Octyl Methoxy Cinnamate Probed via Laser Interfaced Mass Spectrometry

“…photodynamics, [6,[10][11][12] and reactive oxygen sensitization, with quantum chemical studies also exploring details of the excited state characteristics. [13][14][15] Intriguingly, a wide variance in the reduction of OMC absorptivity has been reported in the various experimental studies, with absorbance being observed to vary greatly under different experimental conditions. While some studies have reported that OMC degrades irreversibly in solution, losing up to 90% of its absorbance, [16] others have found that it forms a photostationary state between the trans and cis isomers with only 30-50% loss of absorption.…”

Theoretical Studies on the Excited-State Decay Mechanism of Homomenthyl Salicylate in a Gas Phase and an Acetonitrile Solution

“…For human beings, an important UV-induced process is the production of vitamin D, which is beneficial to human health. However, the overexposure to UV radiation is frequently related to sunburn, photoaging, skin cancers, etc. − Sunscreens can provide effective photoprotection for human skin, in which sunscreen filters work through facilitating the safe dissipation of excess UV radiation as heat to environments. − Given recent concerns on the efficiency and safety of current sunscreen filters, unraveling photoprotection mechanisms of nature and artificial sunscreen filters has attracted a lot of experimental and theoretical interests. − …”