A temperature-dependent tricoloured mechanochromic fluorescence material with polymorphic structures

Abstract

High-contrast mechanochromic fluorescence materials are highly appealing due to their potential applications in security, anti-counterfeiting and memory. Considering that polymorphic molecules usually exhibit reversible mechanochromism, we adopted polymorph prediction to predict the potential polymorphs of two D–π–A molecules with the same electron donor but different electron acceptors. The calculation results indicate that the molecule with dicyanomethylene as an acceptor might crystallize in diverse polymorphs with no or intense intermolecular π–π interactions. The obtained three single crystal structures of the compound are well in accordance with the predicted results. The transition between monomers and π-clusters of the molecule could be realized by external stimuli, imparting its high-contrast tricolored mechanochromic property. In addition, its mechanochromic property is temperature-dependent, showing programmed emission change under the united forces. This work provides an effective strategy for the development of high-contrast mechanochromic molecules.