Constructing Regioregular Star Poly(3-hexylthiophene) via Externally Initiated Kumada Catalyst-Transfer Polycondensation

A synthetic route was developed for the preparation of di- and trifunctional Ni complex-based initiators. Each initiator affords well-defined 2-arm (V-shaped) and 3-arm (Y-shaped) regioregular poly(3-hexylthiophene) (rr-P3HT) with controlled molecular weight and narrow polydispersities by the externally initiated Kumada catalyst-transfer polycondensation. The core spacer length and end o-tolylhalide group of the functional initiators exhibited differences in reactivity and show that the biphenyl spacers are effective for the synthesis of V-shaped and Y-shaped rr-P3HTs.