Mechanofluorochromic (MFC) materials display fluorescence color and/or intensity changes in response to mechanical forces, such as grinding, pressing, and shearing. Potential applications of MFC materials include sensors, displays, security printing, and data-storage devices. While many dichromatic MFC systems have been developed, multicolor counterparts that allow multicolor fluorescence drawings are rare. Previous strategies toward multicolor fluorescence drawings adopted two chromophores or components of different responses to temperature and mechanical forces and performed the drawing with careful control of temperatures, mechanical forces, and supramolecular structures. In this presentation, a new strategy for multicolor fluorescence drawing with a single chromophore on thin solid films with mechanical forces will be demonstrated.<br/>The key components to our success of the new strategy are several. For materials design, the rigid bulky H-shaped pentiptycene scaffold is essential. The nonplanar pentiptycene groups could minimize aggregation-induced fluorescence quenching, create cavities for guest diffusion, and facilitate force-induced phase transition. For fluorescence color tuning, vapofluorochromism is operated, in which the solid-vapor host-guest interactions led to fluorescent exciplexes with the color depending on the electron-donating ability of the aniline guests. For multicolor drawing, the force-induced fluorescence-color memory is the key. The decreased fluorescence responsibility of ground vs unground samples to new guest molecules allows one to perform multicolor fluorescence drawings. A particular example of “an apple, an orange, and a banana” has been performed with the pentiptycene-derived 9,10-bis(phenylethynyl)anthracene (9,10-Pp). The relative performance of its position isomers, including 1,4-, 1,5-, 1,8-, and 2,6-Pp provides insights into the structure-property relationship.

Materials for multicolor fluorescence drawings

251st National Meeting (2016)

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