3 - Clean synthetic approaches toward small-molecule organic electronics

Abstract

Organic π-conjugated small molecules have become a promising semiconductor materials to fabricate a variety of organic electronic devices, such as organic field-effect transistors, organic light-emitting diodes, organic solar cells, and sensors, due to their light weight, large synthetic diversity of finely tunable structures, and good reproducibility of batch preparation compared to polymers. The construction of π-conjugated system generally involves traditional Stille and Suzuki coupling reactions requiring organometallic intermediates, which bring environmental risks. Thus a number of clean synthetic methodologies for organic semiconductors have been developed to appeal sustainable economic and social development. In this chapter, the related advances in green synthetic strategies for organic π-conjugated small molecules will be in-depth described from the following three aspects: (1) the definition of green synthesis and green metrics; (2) C–C coupling reactions including traditional cross-coupling reactions, C–X/C–X homo-coupling reactions, metal-free nucleophilic reagents, C–H activation, and C–S activation; and (3) one-pot synthesis. The analyses and comparison of various green synthetic protocols may provide a constructive guidance for the further development of highly efficient and eco-friendly synthesis of small molecules in organic electronics.