Mechanochemical Release of 9,10-Diphenylanthracene via Flex-Activation of Its 1,4-Diels-Alder Adduct

Flex-activated mechanophores capable of releasing small molecules utilize bond bending to facilitate their mechanochemical activation without compromising the overall macromolecular architecture, which have great potential in various applications. However, the development of such mechanophores remains underexplored. Here we report a novel flex-activated mechanophore based on the 1,4-Diels-Alder (DA) adduct of 9,10-diphenylanthracene (DPA) with acetylenedicarboxylate (ADC). Compression of the mechanophore-crosslinked polymer networks mechanochemically activates the weakly fluorescent DPA-ADC mechanophores to undergo a retro-DA reaction in accompany with the release of highly fluorescent DPA molecules (quantum yield close to unity), as confirmed by fluorescence spectroscopy and gas chromatography-mass spectrometry (GC-MS) analysis. As a new member of the small family of flex-activated mechanophores, this fluorogenic DPA-ADC mechanophore possesses promising applications in stress sensing and damage detection.