Unconventional Modulation of Diarylethene Photoswitches

Licentiate thesis, 2022

Light can be manipulated and modulated to fit a particular need or application, such as overcoming a spectral mismatch when facilitating a high energy photochemical reaction. This can be of use in various applications, including solar energy conversion and biological contexts. Photochromic molecules, or molecular photoswitches, undergo photoisomerization reactions when subjected to light of different wavelengths, which can be tracked in situ by spectroscopic techniques such as UV-vis absorption and fluorescence. In this thesis, the photoisomerization and fluorescence of diarylethene photoswitches are modulated by three unconventional methods. The methods are unconventional in the sense that the photochemical processes are not induced by direct excitation. Instead, the photochemistry in the three included papers is respectively facilitated by rapid modulation of light that is not absorbed by the fluorescent isomer, triplet sensitization using hybrids of nanocrystals and organic mediators, or triplet-triplet annihilation photon upconversion. While further improvements are needed for these methods to reach their full potential, the findings in this thesis brings us closer to visible-light control of high energy photochemical transformations.