With the growing concern regarding commercially available ultraviolet (UV) filters damaging the environment, there is an urgent need to discover new UV filters. A family of molecules called mycosporines and mycosporine-like amino acids (referred to as MAAs collectively) are synthesized by cyanobacteria, fungi and algae and act as the natural UV filters for these organisms. Mycosporines are formed of a cyclohexenone core structure while mycosporine-like amino acids are formed of a cyclohexenimine core structure. To better understand the photoprotection properties of MAAs, we implement a bottom-up approach by first studying a simple analog of an MAA, 3-aminocyclohex-2-en-1-one (ACyO). Previous experimental studies on ACyO using transient electronic absorption spectroscopy (TEAS) suggest that upon photoexcitation, ACyO becomes trapped in the minimum of an S₁ state, which persists for extended time delays (>2.5 ns). However, these studies were unable to establish the extent of electronic ground state recovery of ACyO within 2.5 ns due to experimental constraints. In the present studies, we have implemented transient vibrational absorption spectroscopy (as well as complementary TEAS) with Fourier transform infrared spectroscopy and density functional theory to establish the extent of electronic ground state recovery of ACyO within this time window. We show that by 1.8 ns, there is >75% electronic ground state recovery of ACyO, with the remaining percentage likely persisting in the electronic excited state. Long-term irradiation studies on ACyO have shown that a small percentage degrades after 2 h of irradiation, plausibly due to some of the aforementioned trapped ACyO going on to form a photoproduct. Collectively, these studies imply that a base building block of MAAs already displays characteristics of an effective UV filter.

随着对可破坏环境的市售紫外线（UV）滤光片的日益关注，迫切需要发现新的紫外线滤光片。蓝细菌，真菌和藻类合成了称为霉菌素和类霉菌素氨基酸（统称为MAA）的分子家族，并充当这些生物的天然紫外线过滤剂。霉菌素由环己烯酮核心结构形成，而霉菌素样氨基酸由环己烯胺​​核心结构形成。为了更好地了解MAA的光保护特性，我们通过首先研究MAA的简单类似物3-aminocyclohex-2-en-1-one（y）。以前的实验研究y 使用瞬态电子吸收光谱法（TEAS）表明，在光激发下， y变得陷于S ₁状态的最小值，该状态持续较长的时间延迟（> 2.5 ns）。但是，这些研究无法确定电子基态恢复的程度。y在2.5 ns内由于实验限制。在目前的研究中，我们已经利用傅立叶变换红外光谱和密度泛函理论实现了瞬态振动吸收光谱（以及互补的TEAS），以建立电子基态恢复的程度。y在此时间范围内。我们表明，到1.8 ns时，有> 75％的电子基态恢复y，剩余的百分比可能会持续处于电子激发态。长期照射研究y 已经表明，辐照2小时后有少量降解，这可能是由于上述某些被困 y继续形成照相产品。总的来说，这些研究表明，MAA的基本组成部分已经显示出有效的紫外线滤光片的特性。