Dithienothiazine oligomers and polymers display significant red shifted luminescence and low oxidation potentials.

No abstract

Dithienothiazine copolymers are efficiently obtained by Suzuki polymerization or in situ lithiation-Negishi polymerization in good to excellent yields. Gel permeation chromatography was applied to characterize the dispersities and degrees of polymerization of these novel materials. Thermogravimetric analysis shows that the copolymers are stable towards sidechain cleavage up to 200 °C. The materials are deep red to black amorphous solids or resins and their absorption and emission spectra in solution reveal broad absorption bands in the visible and orange to deep red luminescence upon UV excitation. According to the optical band gaps these novel copolymers qualify as a new class of low band gap organic semiconductors.

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.