Pyrene boronic acid cyclic ester: a new fast self-recovering mechanoluminescent material at room temperature.

Two pyrene boronic acid cyclic esters, PPB and NPB, were prepared and their solid state fluorescence properties were investigated. Interestingly, the results showed that PPB with a 5-membered ring possessed reversible mechanoluminescence and vapochromic behaviour with a fast self-recovering ability at room temperature, whereas NPB with a 6-membered ring did not. It was demonstrated that the mechanically responsive fluorescence properties of PPB and NPB were highly related to the molecular packing mode and the solid state plasticity.