Nickel-Catalyzed Suzuki Polycondensation for Controlled Synthesis of Ester-Functionalized Conjugated Polymers

Abstract

Controlled synthesis of conjugated polymers with functional side chains is of great importance, affording welldefined optoelectronic materials possessing enhanced stability and tunability as compared to their alkyl-substituted counterparts. Herein, a chain-growth Suzuki polycondensation of an ester-functionalized thiophene is described using commercially available nickel precatalysts. Model compound studies were used to identify suitable catalysts, and these experiments provided guidance for the polymerization of the ester-substituted monomer. This is the first report of nickel-catalyzed Suzuki cross-coupling for catalyst-transfer polycondensation, and to further illustrate the versatility of this method, block and alternating copolymers with 3-hexylthiophene were synthesized. The presented protocol should serve as an entry point into the synthesis of other electron-deficient polymers and donor−acceptor copolymers with controlled molecular weights and low dispersity.

Diversifying Cross‐Coupling Strategies, Catalysts and Monomers for the Controlled Synthesis of Conjugated Polymers

“…Both dppp and dppe based catalysts have been used to polymerize a broad range of monomers (Figures and 4). These include phenylenes, thiophenes, pyrroles, furans, selenophenes, tellurophenes, thiazoles, pyridines, fluorenes, thienopyrazines, dithienosiloles, carbazole and rylene diimides . In each of these cases, dramatic differences arise when exploring these different conjugated building blocks.…”

“…These are used less than bidentate phosphines for Ni‐CTP as they are often less stable in solution. Monodentate phosphines (Figure ) have catalyzed CTP only for thiophenes to date . Kiriy and co‐workers utilized Ni(PPh 3 ) 2 Cl 2 catalysts to explore ring‐walking and chain‐growth for bithiophene and terthiophene monomers .…”

“…Kiriy and co‐workers utilized Ni(PPh 3 ) 2 Cl 2 catalysts to explore ring‐walking and chain‐growth for bithiophene and terthiophene monomers . Noonan and co‐workers explored a Ni(PCy 3 ) 2 (1‐Nap)Br pioneered by Percec's group to polymerize (3‐hexylester)thiophenes using Suzuki–Miyaura coupling . The catalyst performed relatively well, but only at high loadings (5 mol %) .…”

“…Noonan and co‐workers explored a Ni(PCy 3 ) 2 (1‐Nap)Br pioneered by Percec's group to polymerize (3‐hexylester)thiophenes using Suzuki–Miyaura coupling . The catalyst performed relatively well, but only at high loadings (5 mol %) . Polymerizations performed with monodentate nickel phosphine catalysts seem to produce more chain‐transfer and termination.…”

Poly(arylenevinylene)s through Ring‐Opening Metathesis Polymerization of an Unsymmetrical Donor‐Acceptor Cyclophane

“…Advancements in catalyst-transfer polymerization (CTP) have achieved D-A conjugated polymers that propagate through ac hain-growth mechanism, [10] yet some systems cannot attain perfectly alternating polymers,w hile others afford ill-controlled molecular weights and suggest al ack of versatility. [11] Additional CTP approaches have realized D-A systems that exhibit some control over molecular structure.…”