Fan Jiayun, Lemmens Alexander K, Sanders Hans, Hilbers Michiel, Roeterdink Wim, Jan Buma Wybren
Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands.
Phys Chem Chem Phys. 2024 Nov 7;26(43):27270-27280. doi: 10.1039/d4cp02087a.
Urocanic acid is a naturally occurring UV-A and UV-B absorbing compound found in the skin. Its use in artificial sunscreens has been abandoned because of health risks associated with the isomer. Here we report laser spectroscopic studies on urocanic acid and various substituted derivatives under supersonically cooled conditions. We find that the spectroscopy and excited-state dynamics of urocanic acid are dominantly determined by the nearly degenerate nπ* and ππ* electronically excited states. These properties are only affected to a minor extent by esterification of the carboxylic acid group or NH alkylation of the NH tautomer. Tautomerization, on the other hand, has a much more profound influence and leads-from a photoprotective point of view-to more favorable excited-state dynamics. The approach presented here paves the way to tailoring the photoactive properties of urocanic acid for specific applications amongst which their use as safe UV filters.
尿刊酸是一种在皮肤中天然存在的能吸收紫外线A和紫外线B的化合物。由于与该异构体相关的健康风险，其在人造防晒剂中的应用已被摒弃。在此，我们报告了在超声冷却条件下对尿刊酸及其各种取代衍生物的激光光谱研究。我们发现，尿刊酸的光谱和激发态动力学主要由近乎简并的nπ和ππ电子激发态决定。这些性质仅在较小程度上受到羧酸基团酯化或NH互变异构体的NH烷基化的影响。另一方面，互变异构化具有更为深远的影响，并且从光保护的角度来看，会导致更有利的激发态动力学。本文提出的方法为针对特定应用定制尿刊酸的光活性性质铺平了道路，其中包括将其用作安全的紫外线滤光剂。
