Trapping a diradical transition state by mechanochemical polymer extension

Lenhardt, JM; Ong, MT; Choe, R; Evenhuis, CR; Martinez, TJ; Craig, SL

Trapping a diradical transition state by mechanochemical polymer extension

Lenhardt, JM Ong, MT Choe, R Evenhuis, CR

Martinez, TJ Craig, SL

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Publication Type:: Journal Article
Citation:: Science, 2010, 329 (5995), pp. 1057 - 1060
Issue Date:: 2010-08-27

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Field	Value	Language
dc.contributor.author	Lenhardt, JM	en_US
dc.contributor.author	Ong, MT	en_US
dc.contributor.author	Choe, R	en_US
dc.contributor.author	Evenhuis, CR https://orcid.org/0000-0001-9903-7716	en_US
dc.contributor.author	Martinez, TJ	en_US
dc.contributor.author	Craig, SL	en_US
dc.date.issued	2010-08-27	en_US
dc.identifier.citation	Science, 2010, 329 (5995), pp. 1057 - 1060	en_US
dc.identifier.issn	0036-8075	en_US
dc.identifier.uri	http://hdl.handle.net/10453/28147
dc.description.abstract	Transition state structures are central to the rates and outcomes of chemical reactions, but their fleeting existence often leaves their properties to be inferred rather than observed. By treating polybutadiene with a difluorocarbene source, we embedded gem-difluorocyclopropanes (gDFCs) along the polymer backbone. We report that mechanochemical activation of the polymer under tension opens the gDFCs and traps a 1,3-diradical that is formally a transition state in their stress-free electrocyclic isomerization. The trapped diradical lives long enough that we can observe its noncanonical participation in bimolecular addition reactions. Furthermore, the application of a transient tensile force induces a net isomerization of the trans-gDFC into its less-stable cis isomer, leading to the counterintuitive result that the gDFC contracts in response to a transient force of extension.	en_US
dc.relation.ispartof	Science	en_US
dc.relation.isbasedon	10.1126/science.1193412	en_US
dc.subject.classification	General Science & Technology	en_US
dc.title	Trapping a diradical transition state by mechanochemical polymer extension	en_US
dc.type	Journal Article
utslib.citation.volume	5995	en_US
utslib.citation.volume	329	en_US
utslib.for	0303 Macromolecular and Materials Chemistry	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - ithree - Institute of Infection, Immunity and Innovation
utslib.copyright.status	closed_access
pubs.issue	5995	en_US
pubs.publication-status	Published	en_US
pubs.volume	329	en_US

Abstract:

Transition state structures are central to the rates and outcomes of chemical reactions, but their fleeting existence often leaves their properties to be inferred rather than observed. By treating polybutadiene with a difluorocarbene source, we embedded gem-difluorocyclopropanes (gDFCs) along the polymer backbone. We report that mechanochemical activation of the polymer under tension opens the gDFCs and traps a 1,3-diradical that is formally a transition state in their stress-free electrocyclic isomerization. The trapped diradical lives long enough that we can observe its noncanonical participation in bimolecular addition reactions. Furthermore, the application of a transient tensile force induces a net isomerization of the trans-gDFC into its less-stable cis isomer, leading to the counterintuitive result that the gDFC contracts in response to a transient force of extension.

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http://hdl.handle.net/10453/28147