Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK.
Department of Chemistry, University of Pennsylvania, Philadelphia, USA.
Chem Soc Rev. 2017 Jun 19;46(12):3770-3791. doi: 10.1039/c7cs00102a.
Evolution has ensured that plants and animals have developed effective protection mechanisms against the potentially harmful effects of incident ultraviolet radiation (UVR). Tanning is one such mechanism in humans, but tanning only occurs post-exposure to UVR. Hence, there is ever growing use of commercial sunscreens to pre-empt overexposure to UVR. Key requirements for any chemical filter molecule used in such a photoprotective capacity include a large absorption cross-section in the UV-A and UV-B spectral regions and the availability of one or more mechanisms whereby the absorbed photon energy can be dissipated without loss of the molecular integrity of the chemical filter. Here we summarise recent experimental (mostly ultrafast pump-probe spectroscopy studies) and computational progress towards unravelling various excited state decay mechanisms that afford the necessary photostability in chemical filters found in nature and those used in commercial sunscreens. We also outline ways in which a better understanding of the photophysics and photochemistry of sunscreen molecules selected by nature could aid the design of new and improved commercial sunscreen formulations.
进化确保了植物和动物发展出了有效的保护机制，以抵御紫外线辐射（UVR）的潜在有害影响。晒黑是人类的一种保护机制，但只有在暴露于 UVR 后才会发生晒黑。因此，人们越来越多地使用商业防晒霜来预防 UVR 过度暴露。任何用于这种光保护能力的化学过滤分子的关键要求包括在 UV-A 和 UV-B 光谱区域具有较大的吸收截面，以及存在一种或多种机制，通过这些机制可以耗散吸收的光子能量，而不会损失化学过滤器的分子完整性。在这里，我们总结了最近在实验（主要是超快泵浦探测光谱学研究）和计算方面的进展，这些进展揭示了在自然界中发现的以及商业防晒霜中使用的化学过滤器中提供必要光稳定性的各种激发态衰减机制。我们还概述了更好地了解自然界选择的防晒霜分子的光物理和光化学特性如何有助于设计新的和改进的商业防晒霜配方。
