A Mechanochemically Triggered “Click” Catalyst

Abstract

"Click" chemistry represents one of the most powerful approaches for linking molecules in chemistry and materials science. Triggering this reaction by mechanical force would enable site- and stress-specific "click" reactions--a hitherto unreported observation. We introduce the design and realization of a homogeneous Cu catalyst able to activate through mechanical force when attached to suitable polymer chains, acting as a lever to transmit the force to the central catalytic system. Activation of the subsequent copper-catalyzed "click" reaction (CuAAC) is achieved either by ultrasonication or mechanical pressing of a polymeric material, using a fluorogenic dye to detect the activation of the catalyst. Based on an N-heterocyclic copper(I) carbene with attached polymeric chains of different flexibility, the force is transmitted to the central catalyst, thereby activating a CuAAC in solution and in the solid state.

Recent advances in mechanoluminescent polymers

“…Cascade mechanoluminescence was also achieved in solid state with bis(NHC)-Cu(I) as the mechanophore [89]. Click reaction of phenylaceylene and benzylazide was conducted accompanied by blue fluorescence emission when Cu(I) center was dissociated as the catalyst site under pressure (Fig.…”

Von der Muschel zum Autolack

“…Kraft aktiviert einen inaktiv vorliegenden Kupfer(I)-Katalysator, der dann durch eine Klickreaktion Fluoreszenz hervorruft und so den Schaden sichtbar macht. 14) einen chemischen Prozess ein, der den Schaden punktgenau repariert (Abbildung 7).…”

“…Der zunächst inaktiv vorliegende Kupfer(I)-basierte Katalysator ist in der Mitte einer Polymerkette lokalisiert, die wie eine Art Gummiband fungiert und in eine semikrstialline Polymermatrix integriert wird (Abbildung 7). 14) Durch Krafteinwirkung reißt das Gummiband an der schwächsten Stelle -in diesem Fall an der Carben-Metallbindung -, was den Katalysator aktiviert. In einer nachfolgenden fluorogenen Klickreaktion reagiert 3-Azido-7-hydroxycumarin mit Phenylacetylen.…”

“…Gleichzeitig startet eine Kupfer(I)-katalysierte Vernetzungsreaktion, sodass der sichtbar gemachte Schaden sich selbst repariert. 14) Da der Katalysator zunächst inaktiv vorliegt, lassen sich die benötigten Selbstheilungsagenzien ohne schützende Verkapselung in das Material einbetten.…”

Ultrasound Promoted Step‐Growth Polymerization and Polymer Crosslinking Via Copper Catalyzed Azide–Alkyne “Click” Reaction

“…We synthesized al inear polyurethane with azide containing pendant groups.T his polymer was then crosslinked with tripropargyl amine via the mechano-click reaction. The approach of using the piezoelectric effect to activate catalysts for CuAAC-mediated reactions in polymeric materials complements others approaches of mechano-click reactions that are mediated by mechanophores [9] (Scheme 1).…”