LAUSR

Abstract Two novel electron accepting bis-isatins, having fused bis-lactam rings have been synthesized from corresponding pyrroloindoles 7 and 14 by one-pot direct oxidation approach involving oxidant NBS with or without co-oxidant TBHP in DMF/CHCl3. Synthesized fused bis-isatins 8 and 15 are extensively studied for thermal, photophysical, electrochemical and thin-film morphological properties and are found to have characteristic properties like solid-solid transitions, visible light absorption, lowered FMO energy levels (LUMOs below −4.1 eV and HOMOs below −5.9 eV) as well as oriented packing of molecules in the film state. The famous indophenine reaction is re-visited with fused bis-isatins to form conjugated polymers P-1 and P-2, having quinoidal pyrroloindole dione units. The polymers are studied for thermal, photophysical, electrochemical and thin-film morphological properties indicating sufficiently high thermal stability (up to 200 °C), extended absorptions up to near IR region, lowered FMO energy levels (LUMOs below −4.3 eV and HOMOs below −5.8 eV) and amorphous nature of polymer films.