A light-induced photochromic nanoswitch capable of non-destructive readout via fluorescence Emission: Cluster vs. single-molecule excitation of dihydroindolizines

We have synthesized a prototype of a photochromic styrylquinolyl- dihydroindolizine (DHI), which forms a highly coloured and fluorescent betaine upon irradiation with λ < 400 nm. Embedding this photochromic DHI in a thin polymethyl methacrylate (PMMA) film permits the non-destructive readout via fluorescence at low temperature (77 K). Thus, either a non-destructive photoswitch or an information recording system becomes available. Both possibilities have been explored: image recording and read-out, as well as information storage (at 77 K) have been demonstrated. Cluster- and single molecule-fluorescence upon laser excitation (λ = 355 nm) of the styrylquinolyl-dihydroindolizine in a PMMA matrix, and the effect of fluorescence blinking has been observed.