Illuminating Sunscreens: New approaches to a molecular understanding of photoprotection

To develop the next generation of sunscreens, it is essential that we gain a broader understanding of the fundamental mechanisms by which a sunscreen molecule functions. In this project, we will conduct novel experiments exploring the basic photochemical properties of key active sunscreen components. Experiments will be performed on isolated gas-phase molecules, free from the influences of the other components in the complex sunscreen mixture. In particular, we propose to investigate the key question of how the properties of a UV organic sunscreen (e.g. oxybenzone) is affected if the molecule is protonated or deprotonated. This critical issue has been almost entirely ignored to date, despite the fact that commercial sunscreen mixtures include large quantities of polar solvents capable of donating to or accepting protons from components in the mixture. The recently developed laser-interfaced electrospray mass spectrometer (CED group) is an ideal tool for producing the sunscreen molecules in their protonated/deprotonated forms in the gas phase. The mass selectivity allows potentially for laser bandwidth limited UV spectra to be recorded not only of the protonate/deprotated molecule but also any photoproducts. Data obtained for the charged sunscreens will then be directly compared to the analogous neutral molecule spectrum obtained using two-colour photoionization spectroscopy (MCRC group). Further experiments will be conducted on aggregates of the organic sunscreen (both neutral and ionic) with inorganic sunscreens (ZnO/TiO2) to perform the first molecular-level investigations of how combining organic and inorganic sunscreens modifies the intrinsic organic sunscreen spectrum and photoproducts. The availability of experimental systems for obtaining the gas-phase UV laser spectra of both neutral and charged sunscreen species within a single department is unique to York, and therefore offers a prime opportunity to perform internationally-leading measurements in this emerging field.

The project will provide broad training opportunities in a range of highly-transferrable skills including mass spectrometry, photochemistry, and laser spectroscopy (use of class 4 laser systems). Training will also be offered in computational chemistry techniques (ab initio and DFT) to support the interpretation of experimental results. The Dessent/Cockett research groups foster a lively scientific environment for students, with regular group meetings, directed literature reading, close links to the other internal and external research groups, rapid publication of post-graduate results and attendance at external UK and international scientific meetings.

Shortlisting will take place as soon as possible after the closing date and successful applicants will be notified promptly. Shortlisted applicants will be invited for an interview to take place at the University of York on Friday 12 May. Candidates will be asked to give a short presentation prior to their interview by an academic panel. All research students follow our innovative Doctoral Training in Chemistry (iDTC): cohort-based training to support the development of scientific, transferable and employability skills

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