Synthesis of a 12-Dithienylethene-Containing Donor-Acceptor Polymer via Palladium-Catalyzed Direct Arylation Polymerization (DArP)

摘要

This paper reports the synthesis of D-A polymers containing 1,2-dithienylethene (DTE) units via palladium-catalyzed direct arylation polymerization (DArP). The reaction of dibromoisoindigo (>1->Br) and DTE (>2->H), in the presence of Pd2(dba)3·CHCl3 (0.5 mol%), P(2-MeOC6H4)3 (>L1) (2 mol%), pivalic acid (1 equiv) as catalyst precursors, and Cs2CO3 (3 equiv) as a base affords poly(>1-alt->2) with a high molecular weight (Mn up to 44,900). Although, it has been known that monomers, with plural C–H bonds, tend to form insoluble materials via direct arylation at undesirable C–H positions; the reaction of >1->Br and >2->H cleanly proceeds without insolubilization. The resulting polymer has a well-controlled structure and exhibits good charge transfer characteristics in an organic field-effect transistor (OFET), compared to the polymer produced by Migita–Kosugi–Stille cross-coupling polymerization. The DArP product displays an ideal linear relationship in the current–voltage curve, whereas the Migita–Kosugi–Stille product shows a VG-dependent change in the charge mobility.