Regiocontrolled synthesis of ester-functionalized polythiophenes via direct arylation polycondensation

A series of ester-functionalized polythiophenes (P3OETs) with precisely controlled head-to-tail (HT) ratios was synthesized via palladium-catalyzed direct arylation polycondensation (DArP). The ionization potentials and optical bandgaps of P3OETs decreased as their HT ratios increased because of the increased backbone coplanarity and extensive π-electron delocalization. The method of precisely controlling the regioregularity and HT ratio can contribute to the design of new polythiophene derivatives with enhanced electronic functionality.