The role of symmetric functionalisation on photoisomerisation of a UV commercial chemical filter

Abstract

Photoisomerisation has been shown to be an efficient excited-state relaxation mechanism for a variety of nature-based and artificial-based molecular systems.

A systematic approach to methyl cinnamate photodynamics

“…Time-dependent DFT calculations were conducted upon this structure at the PBE0/ aug-pVTZ level of theory to calculate vertical excitation energies for both singlet and triplet excited states and are presented in section S3 of SM. This level of theory has been used successfully in the literature in previous studies on other organic chromophores [51][52][53]. Figure 2 (top) presents TR-Iϒ and TR-PES transients of trans-MC respectively along with the extracted timeconstants.…”

Applications of ultrafast spectroscopy to sunscreen development, from first principles to complex mixtures

“…This study sought to deepen the knowledge of the isomerisation that takes place within cinnamates, the subject of many previous studies [145-147, 197, 210, 215, 216]. Specifically, by adding an additional methyl acrylate moiety on to methyl cinnamate, structure shown in Figure 4, the effect of symmet- Woolley et al [214] conclude from this study that E,E-DPD evolves from the Franck-Condon region of the S 1 state on a comparable timescale (< 1 ps), to EHMC after the initial photoexcitation (τ 1 , Figure 5). However, the length of time to traverse the S 1 potential energy surface through the S 1 /S 0 CI and repopulate the S 0 state, representing the lifetime of isomerisation (to regenerate E,E-DPD or form E,Z-DPD), increased 5-fold in the E,E-DPD species (∼10 ps) [214], compared to ∼2 ps for EHMC [197] (τ 2 , Figure 5).…”

“…Through steady-state irradiation, i.e. exposing the molecules to equivalent solar fluences for a prolonged period (in this case two hours), Woolley et al [214] determined that the absorbance of the E,Z species is spectrally blue-shifted compared to that of the E,E species; this blue shift was also predicted using computational methods [214].…”

“…Molecular structures of the precursor molecule, methyl cinnamate, alongside the three geometric isomers synthesised by Woolley et al[214] with an additional methyl acrylate moiety: E,E-DPD, E,Z-DPD and Z,Z-DPD.rical functionalisation on the isomerisation of cinnamates could be investigated. The motivation for additional moieties is largely driven by alleviating safety concerns associated with trans-cis isomerisation, and the potential avoidance of known endocrine disruption characteristics and coral bleaching effects[96,217].…”

“…One immediate benefit of E,E-DPD was that its absorption peak was red-shifted into the UVA region, where new options for inclusion in sunscreens are needed[69]. A range of solvents of different polarity and protic characteristics were chosen for the study by Woolley et al[214]: acetonitrile, ethanol and cyclohexane, with the pump wavelength set to the UV-visible absorption maximum for E,E-DPD in the respective solvent.…”