Ultrafast photoreaction dynamics of oxindole-based molecular switches

We use femtosecond UV-Vis absorption spectroscopy to investigate the photoreaction mechanism of a recently synthesized oxindole-based molecular switch showing a large C=C double bond photoisiomerization quantum yield (50%), and promising applications e.g. in photopharmacology. Due to an electron-donating phenol moeity, the molecular switch exhibits a push-pull electronic effect which affects its photophysical properties. In solvents of various polarities and hydrogen bonding capabilities, we observe a faster (sub-ps) photoisomerization dynamics of the deprotonated phenolate form of the compound, where the push-pull effect is enhanced. This work aims at unraveling the synthetic design strategies towards optimizing the photoreaction dynamics and quantum yiled of such molecular switches.