title: Mechanical gating of a mechanochemical reaction cascade.
abstract: Covalent polymer mechanochemistry offers promising opportunities for the control and engineering of reactivity. To date, covalent mechanochemistry has largely been limited to individual reactions, but it also presents potential for intricate reaction systems and feedback loops. Here we report a molecular architecture, in which a cyclobutane mechanophore functions as a gate to regulate the activation of a second mechanophore, dichlorocyclopropane, resulting in a mechanochemical cascade reaction. Single-molecule force spectroscopy, pulsed ultrasonication experiments and DFT-level calculations support gating and indicate that extra force of >0.5 nN needs to be applied to a polymer of gated gDCC than of free gDCC for the mechanochemical isomerization gDCC to proceed at equal rate. The gating concept provides a mechanism by which to regulate stress-responsive behaviours, such as load-strengthening and mechanochromism, in future materials designs.
authors.affiliation: Department of Chemistry, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Junpeng
authors.identifier: 0000-0002-4503-5026
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Tatiana B
authors.initials: TB
authors.lastname: Kouznetsova
authors.affiliation: Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
authors.forename: Roman
authors.initials: R
authors.lastname: Boulatov
authors.affiliation: Department of Chemistry, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Stephen L
authors.identifier: 0000-0002-8810-0369
authors.initials: SL
authors.lastname: Craig