Living Suzuki-Miyaura Catalyst-Transfer Polymerization for Precision Synthesis of Length-Controlled Armchair Graphene Nanoribbons and Their Block Copolymers
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Date
2023-07-19Type
- Journal Article
Abstract
The bottom-up synthesis of graphene nanoribbons (GNRs) offers a promising approach for designing atomically precise GNRs with tuneable photophysical properties, but controlling their length remains a challenge. Herein, we report an efficient synthetic protocol for producing length-controlled armchair GNRs (AGNRs) through living Suzuki–Miyaura catalyst-transfer polymerization (SCTP) using RuPhos–Pd catalyst and mild graphitization methods. Initially, SCTP of a dialkynylphenylene monomer was optimized by modifying boronates and halide moieties on the monomers, affording poly(2,5-dialkynyl-p-phenylene) (PDAPP) with controlled molecular weight (Mₙ up to 29.8k) and narrow dispersity (Đ = 1.14–1.39) in excellent yield (>85%). Subsequently, we successfully obtained N = 5 AGNRs by employing a mild alkyne benzannulation reaction on the PDAPP precursor and confirmed their length retention by size-exclusion chromatography. In addition, photophysical characterization revealed that a molar absorptivity was directly proportional to the length of the AGNR, while its highest occupied molecular orbital (HOMO) energy level remained constant within the given AGNR length. Furthermore, we prepared, for the very first time, N = 5 AGNR block copolymers with widely used donor or acceptor-conjugated polymers by taking advantage of the living SCTP. Finally, we achieved the lateral extension of AGNRs from N = 5 to 11 by oxidative cyclodehydrogenation in solution and confirmed their chemical structure and low band gap by various spectroscopic analyses. Show more
Publication status
publishedExternal links
Journal / series
Journal of the American Chemical SocietyVolume
Pages / Article No.
Publisher
American Chemical SocietySubject
Chemical structure; Conjugated polymers; Monomers; PalladiumOrganisational unit
09767 - Choi, Tae-Lim / Choi, Tae-Lim
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