Synthesis and Electronic Properties of Conjugated syn,syn‐Dithienothiazine Donor‐Acceptor‐Donor Dumbbells

Abstract

A series of conjugated syn,syn‐dithienothiazine donor‐acceptor‐donor dumbbells is readily synthesized by Suzuki coupling or a one‐pot α‐lithiation‐zincation‐Negishi coupling sequence in moderate to good yield. The title compounds are all electron‐rich reversible oxidizable redox systems with a relatively narrow range of oxidation potentials according to cyclic voltammetry. UV/Vis and fluorescence spectroscopy however show a significant effect of the electronic nature of the conjugated bridging system on absorption and emission characteristics. Furthermore, a highly polar excited state can be corroborated by Lippert‐Mataga analysis of the emission solvatochromicity as well as by TD‐DFT calculation of absorption and emission maxima, which classify these dumbbell systems as redox active, luminescent low band gap chromophores with experimentally determined optical band gaps between 2.20 and 2.50 eV.

Bis[1]benzothieno[1,4]thiaborins as a Platform for BODIPY Singlet Oxygen Photosensitizers

“…As the device performance ultimately originates from the molecular properties, the incorporation of electron-rich atoms such N, P or S emerged as an attractive method to modulate the electronic structure of the material. [12][13][14][15][16][17] For instance, electron-rich heterocycles such as phenothiazines [6,18,19] and their dithienyl congeners, namely dithieno [1,4]thiazines, [20][21][22][23] have attracted a of lot interest due to their low oxidation potentials and reversibility of the redox processes, as well as NIR luminescence. [24] Furthermore, the expansion of the dithieno [1,4]thiazines to the pentacyclic bis [1](benzothienylo) [1,4]thiazine (BBTT, Scheme 1) strongly favors luminescent behavior.…”