Elucidating nuclear motions in a plant sunscreen during photoisomerization through solvent viscosity effects.

We explore the effects of solvent viscosity on the trans-cis photoisomerization of sinapoyl malate, which is utilized as a sunscreen molecule in plants. Our results demonstrate that viscosity has a significant effect on the timescale for isomerization, providing insight into the nuclear motions involved. The ramifications of these findings are discussed with reference to sinapoyl malate's in vivo photoprotection properties.