Pyrylenes: A New Class of Tunable, Redox-Switchable, Photoexcitable Pyrylium–Carbene Hybrids with Three Stable Redox-States
datasetposted on 2018-10-10, 00:00 authored by Patrick W. Antoni, Max M. Hansmann
A new synthetic and modular access to a large family of redox-switchable molecules based upon the combination of pyrylium salts and carbenes is presented. The redox-properties of this new molecule class correlate very well with the π-accepting properties of the corresponding carbenes. While the pyrylium moiety acts as a chromophore, the carbene moiety can tune the redox-properties and stabilize the corresponding radicals. This leads to the isolation of the first monomeric pyranyl-radical in the solid-state. The three stable oxidation states could be cleanly accessed by chemical oxidation, characterized by NMR, EPR, UV–vis, and X-ray diffraction and supported by (TD)-DFT-calculations. The new hybrid class can be utilized as an electrochemically triggered switch and as a powerful photoexcited reductant. Importantly, the pyrylenes can be used as novel photocatalysts for the reductive activation of aryl halides and sulfonamides by consecutive visible light induced electron transfer processes.
chemical oxidationmolecule classStable Redox-StatesX-ray diffractionredox-switchable moleculesoxidation statesredox-propertiearyl halidesTDpyrylium moiety actselectron transfer processesNew Classpyrylium saltsnovel photocatalystsreductive activationmonomeric pyranyl-radicalEPRNMRUVcarbene moietyphotoexcited reductant