Synthesis of Diketopyrrolopyrrole Based Photoactive Materials via Photoredox C−H Activation

Abstract

The synthesis of diketopyrrolopyrrole (DPP) derivatives followed the well-known conventional cross-coupling methods such as Suzuki, Stille, Sonogashira, and Negishi cross-coupling reactions. However, these methods required unfavorable reaction conditions, organometallic precursors, and high temperatures. In addition, the synthesis of conventional cross-coupling partners including organoboranes, stannane, and acetylenes required drastic reaction conditions and strong bases. In this work, a wide variety of thiophene-diketopyrrolopyrrole (TDPP)-based semiconducting materials (36 compounds) were synthesized via Pd-catalysed photoredox methodology by using N-hydroxyphthalimide (NHP) based coupling partners, which can be readily prepared from N-hydroxyphthalimide and carboxylic acid or aldehyde derivatives via single step C−O bond formation reactions with good yield (80–90 %). This methodology minimizes additional synthetic steps, harsh reaction conditions, and high temperature (100–150 °C). Optoelectronic studies suggest that the synthesized materials have suitable band gap, HOMO and LUMO levels for variety of optoelectronic applications. To the best of our knowledge, this is the first report on the synthesis of TDPP-based π-conjugated materials via the photoredox method.