Substituent effects in a six-state molecular switch†

This paper describes a series of four indolinooxazolidine molecular switches capable of accessing multiple distinct states by separately addressing photo- and stereo-isomerism. Photoswitches serve as valuable components in molecular devices owing to their ability to isomerize between distinct states using light as a non-invasive input. While most photoswitches are binary, converting between two states, multistate switches offer expanded operational capabilities and show promise for multi-bit architectures. We synthesized a series of four indolinooxazolidines with varied electronic structure and examined their switching behavior in different solvents. While electron-withdrawing substituents inhibit the photoisomerization pathway, the incorporation of an oligoethylene glycol chain enables both reversible photoisomerisation and acidochromic switching between six combinations of photo- and stereo-isomers.