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Between Aromatic and Quinoid Structure: A Symmetrical UV to Vis/NIR Benzothiadiazole Redox Switch |
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| Authors: | Philipp Rietsch Dr Sebastian Sobottka Dr Katrin Hoffmann Dr Alexey A Popov Pascal Hildebrandt Prof Dr Biprajit Sarkar Dr Ute Resch-Genger Prof Dr Siegfried Eigler |
| Institution: | 1. Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
These authors contributed equally to this work.;2. Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstraße 34–36, 14195 Berlin, Germany These authors contributed equally to this work.;3. Department 1, Division Biophotonics, Bundesanstalt für Materialforschung und -prüfung (BAM), Richard Willstätter Straße 11, 12489 Berlin, Germany;4. Leibniz Institute for Solid State and Materials Research, Helmholtzstraße 20, 01069 Dresden, Germany;5. Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany;6. Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstraße 34–36, 14195 Berlin, Germany Chair of Inorganic Coordination Chemistry, Institute of Inorganic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany |
| Abstract: | Reversibly switching the light absorption of organic molecules by redox processes is of interest for applications in sensors, light harvesting, smart materials, and medical diagnostics. This work presents a symmetrical benzothiadiazole (BTD) derivative with a high fluorescence quantum yield in solution and in the crystalline state and shows by spectroelectrochemical analysis that reversible switching of UV absorption in the neutral state, to broadband Vis/NIR absorption in the 1st oxidized state, to sharp band Vis absorption in the 2nd oxidized state, is possible. For the one-electron oxidized species, formation of a delocalized radical is confirmed by electron paramagnetic resonance spectroelectrochemistry. Furthermore, our results reveal an increasing quinoidal distortion upon the 1st and 2nd oxidation, which can be used as the leitmotif for the development of BTD based redox switches. |
| Keywords: | benzothiadiazoles fluorescence molecular switches quinones spectroelectrochemistry |