Issue 48, 2021

Precision synthesis of a fluorene-thiophene alternating copolymer by means of the Suzuki–Miyaura catalyst-transfer condensation polymerization: the importance of the position of an alkyl substituent on thiophene of the biaryl monomer to suppress disproportionation

Abstract

The Suzuki–Miyaura catalyst-transfer condensation polymerization (CTCP) of fluorene-thiophene biaryl monomers was investigated for the synthesis of well-defined poly(fluorene-alt-thiophene). Model reactions of α,ω-dibromo(fluorene-thiophene) with arylboronic acid esters showed that t-Bu3PPd and di-tert-butyl(4-dimethylaminophenyl)phosphine (AmPhos) Pd catalysts undergo intramolecular catalyst transfer from fluorene to thiophene, irrespective of the use of phenyl- or thiopheneboronate. Based on the results of the model reactions, PinB-fluorene-thiophene-Br (PinB = pinacol boronate) monomers were synthesized. The polymerization of the monomer containing the 3-octyl-5-bromothiophene-2-yl unit was accompanied by disproportionation, whereas the polymerization of the monomer containing the 4-octyl-5-bromothiophene-2-yl unit with an AmPhos Pd initiator proceeded according to the CTCP mechanism: the Mn values of the obtained polymers increased in proportion to monomer conversion and to the feed ratio of the monomer to initiator. Moreover, successive CTCP using the fluorene-thiophene monomer, dioctylfluorene monomer, and 3-hexylthiophene monomer with the AmPhos Pd initiator yielded a variety of all-conjugated di- and triblock copolymers.

Graphical abstract: Precision synthesis of a fluorene-thiophene alternating copolymer by means of the Suzuki–Miyaura catalyst-transfer condensation polymerization: the importance of the position of an alkyl substituent on thiophene of the biaryl monomer to suppress disproportionation

Supplementary files

Article information

Article type
Paper
Submitted
01 Ndz 2021
Accepted
03 Huk 2021
First published
19 Huk 2021

Polym. Chem., 2021,12, 7065-7072

Precision synthesis of a fluorene-thiophene alternating copolymer by means of the Suzuki–Miyaura catalyst-transfer condensation polymerization: the importance of the position of an alkyl substituent on thiophene of the biaryl monomer to suppress disproportionation

Y. Tokita, M. Katoh, K. Kosaka, Y. Ohta and T. Yokozawa, Polym. Chem., 2021, 12, 7065 DOI: 10.1039/D1PY01184G

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