A Mechanochemically Gated Fluorescent Probe

Mechanochemical gating of chemical reactions has promising potential for applications ranging from controlled polymer degradation to triggered drug release, but it remains underexplored. A mechanochemically gated molecular probe can be developed by masking either its receptor or reporter with a mechanophore, extending the concept of mechanochemical gating to chemical sensing. Here we demonstrate this concept by reporting a latent fluorescent probe with an anthracene–maleimide Diels–Alder adduct mechanophore as the masked fluorophore and an aza-crown ether as the receptor. Upon mechanochemical activation, the mechanophore undergoes a retro-Diels–Alder reaction, exposing the fluorophore and thus activating the probe for cations (potassium ions in particular) based on N-(9-anthracenylmethyl)aza-18-crown-6. We believe that this work establishes a general design principle for mechanochemically gated probes, advancing the development of smart stress and chemical sensing systems.