Photoisomerization of an Azobenzene-Containing Surfactant Within a Micelle

Photosensitive azobenzene-containing surfactants have attracted great attention in past years because they offer a means to control soft-matter transformations with light. At concentrations higher than the critical micelle concentration (CMC), the surfactant molecules aggregate and form micelles, which leads to a slowdown of the photoinduced trans -> cis azobenzene isomerization. Here, we combine nonadiabatic dynamics simulations for the surfactant molecules embedded in the micelles with absorption spectroscopy measurements of micellar solutions to uncover the reasons responsible for the reaction slowdown. Our simulations reveal a decrease of isomerization quantum yields for molecules inside the micelles. We also observe a reduction of extinction coefficients upon micellization. These findings explain the deceleration of the trans -> cis switching in micelles of the azobenzene-containing surfactants.

Automated summary

In this study, a combination of simulations and experimental measurements was used to uncover the reasons behind the deceleration of photoinduced trans -> cis switching in micelles of azobenzene-containing surfactants. The decrease in isomerization quantum yields for molecules inside the micelles and the reduction of extinction coefficients upon micellization were identified as the key factors responsible for the reaction slowdown. These findings provide a detailed explanation for the observed phenomenon.