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Living β-selective cyclopolymerization using Ru dithiolate catalysts

Jung, Kijung and Ahmed, Tonia S. and Lee, Jaeho and Sung, Jong-Chan and Keum, Hyeyun and Grubbs, Robert H. and Choi, Tae-Lim (2019) Living β-selective cyclopolymerization using Ru dithiolate catalysts. Chemical Science, 10 (39). pp. 8955-8963. ISSN 2041-6520. PMCID PMC6855257. https://resolver.caltech.edu/CaltechAUTHORS:20190814-085859237

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Abstract

Cyclopolymerization (CP) of 1,6-heptadiyne derivatives is a powerful method for synthesizing conjugated polyenes containing five- or six-membered rings via α- or β-addition, respectively. Fifteen years of studies on CP have revealed that user-friendly Ru-based catalysts promoted only α-addition; however, we recently achieved β-selective regiocontrol to produce polyenes containing six-membered-rings, using a dithiolate-chelated Ru-based catalyst. Unfortunately, slow initiation and relatively low catalyst stability inevitably led to uncontrolled polymerization. Nevertheless, this investigation gave us some clues to how successful living polymerization could be achieved. Herein, we report living β-selective CP by rational engineering of the steric factor on monomer or catalyst structures. As a result, the molecular weight of the conjugated polymers from various monomers could be controlled with narrow dispersities, according to the catalyst loading. A mechanistic investigation by in situ kinetic studies using ^1H NMR spectroscopy revealed that with appropriate pyridine additives, imposing a steric demand on either the monomer or the catalyst significantly improved the stability of the propagating carbene as well as the relative rates of initiation over propagation, thereby achieving living polymerization. Furthermore, we successfully prepared diblock and even triblock copolymers with a broad monomer scope.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1039/c9sc01326aDOIArticle
http://www.rsc.org/suppdata/c9/sc/c9sc01326a/c9sc01326a1.pdfPublisherSupplementary Information
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6855257PubMed CentralArticle
ORCID:
AuthorORCID
Lee, Jaeho0000-0001-7584-920X
Grubbs, Robert H.0000-0002-0057-7817
Choi, Tae-Lim0000-0001-9521-6450
Additional Information:© 2019 The Royal Society of Chemistry. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. The article was received on 18 Mar 2019, accepted on 22 Jul 2019 and first published on 22 Jul 2019. The financial support from Creative Research Initiative Program and the Nano-Material Technology Development Program through NRF is acknowledged. We thank NCIRF at SNU for in situ kinetic experiments using ^1H NMR. There are no conflicts to declare.
Funders:
Funding AgencyGrant Number
National Research Foundation of KoreaUNSPECIFIED
Issue or Number:39
PubMed Central ID:PMC6855257
Record Number:CaltechAUTHORS:20190814-085859237
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190814-085859237
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97878
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:14 Aug 2019 16:07
Last Modified:25 Nov 2019 16:02

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