Institution: | 1. School of Chemistry, The University of Melbourne, 3010 Parkville (VIC), Australia
Both authors contributed equally to this work;2. Department für Chemie and Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
Both authors contributed equally to this work;3. School of Chemistry, The University of Melbourne, 3010 Parkville (VIC), Australia;4. School of Chemistry, The University of Melbourne, 3010 Parkville (VIC), Australia
School of Chemistry, Norwich Research Park, University of East Anglia, Norwich, NR4 7TJ United Kingdom;5. Department für Chemie and Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, 81377 Munich, Germany |
Abstract: | Indigoid chromophores have emerged as versatile molecular photoswitches, offering efficient reversible photoisomerization upon exposure to visible light. Here we report synthesis of a new class of permanently charged hemiindigos (HIs) and characterization of photochemical properties in gas phase and solution. Gas-phase studies, which involve exposing mobility-selected ions in a tandem ion mobility mass spectrometer to tunable wavelength laser radiation, demonstrate that the isolated HI ions are photochromic and can be reversibly photoswitched between Z and E isomers. The Z and E isomers have distinct photoisomerization response spectra with maxima separated by 40–80 nm, consistent with theoretical predictions for their absorption spectra. Solvation of the HI molecules in acetonitrile displaces the absorption bands to lower energy. Together, gas-phase action spectroscopy and solution NMR and UV/Vis absorption spectroscopy represent a powerful approach for studying the intrinsic photochemical properties of HI molecular switches. |