Abstract
Transient absorption spectroscopy reveals the excited state dynamics of meta- and para-methyl anthranilate in solution. Implicit solvent computational methods insufficiently model these systems's behaviour, implying the need for explicit solvent models.
Highlights
While human skin is naturally equipped with its own forms of photoprotection, in the form of melanin, a pigment which absorbs harmful radiation before it reaches vulnerable skin cells, this protection is a delayed response that is often insufficient against overexposure to solar radiation.[8,9] In order to complement the skin’s natural forms of photoprotection, the use of sunscreens – commercial formulations containing chemical UV filters, physical UV blockers or, often, both – is common practice
The observed Stokes shifts, i.e. the energy difference between peak absorption and peak emission, increase significantly with increasing solvent polarity, taking values of 37 nm (3317 cmÀ1) in CHX, 77 nm (5960 cmÀ1) in ACN and 102 nm (7431 cmÀ1) in EtOH. This behaviour is characteristic of p-conjugated intramolecular donor–acceptor systems, in which excited states with charge-transfer (CT) character are sensitive to the solvent environment.[30,31,32,33]
A full investigation of the energy surface of the Section 1 (S1) state of m-MA may well require an explicit representation of the solvent, but the computational effort required to locate this minimum is beyond the scope of this study
Summary
While human skin is naturally equipped with its own forms of photoprotection, in the form of melanin, a pigment which absorbs harmful radiation before it reaches vulnerable skin cells, this protection is a delayed response that is often insufficient against overexposure to solar radiation.[8,9] In order to complement the skin’s natural forms of photoprotection, the use of sunscreens – commercial formulations containing chemical UV filters, physical UV blockers or, often, both – is common practice. The chemical UV filters contained in commercial sunscreen formulations are required to be nontoxic to humans and the environment while allowing for the production of a pleasant formulation.
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