A Defect-Free Naphthalene Diimide Bithiazole Copolymer via Regioselective Direct Arylation Polycondensation

摘要

An optimized direct arylation polycondensation (DAP) protocol for the synthesis of a novel naphthalene diimide (NDI) 2,2′-bithiazole (2-BTz) copolymer (PNDI-2-BTz) is presented. The regioselective C-H activation of 2-BTz at the 5-positions allows for the synthesis of fully regioregular and homocoupling- free PNDI-2-BTz of high molecular weight in less than 1 h in quantitative yield. Complete end group assignment shows functionalities according to monomer structures or to nucleophilic substitution, and allows for the reliable determination of absolute molecular weight. Compared to the wellknown bithiophene analog PNDIT2, an exceptionally high thermal stability, a hypsochromically shifted charge transfer absorption band and a lower-lying LUMO energy level is found, making PNDI-2-BTz an interesting candidate for applications in organic electronic devices. In contrast to the selective and high yielding C-H activation of 2-BTz at the 5-position, the regioisomer 5,5′-bithiazole is inactive under a variety of conditions.