Stimuli-responsive materials are of interest for sensors, memory storage, light-emitting diodes and other optical devices. One example of photofunctional systems are mechanochromic luminescent (ML) materials that respond to external forces (i.e. grinding, shearing or smearing) with a change in their fluorescence. Liquid crystals, polymers, inorganic complexes and organic compounds are reported to exhibit this behavior. The emissive properties of ML materials strongly depend on their intermolecular packing; therefore, applying external forces can affect the switching of solid-state assemblies from one form to another without altering individual molecular structure. One explanation for the ML phenomenon is the formation of J- and H-aggregates, where shifts in absorption and emission spectra are caused by mere variation in the slippage angle of the stacked molecules. However, for many ML materials, the structure–property relationships remain unclear. Difluoroboron β‑diketonate complexes (BF<sub>2</sub>bdks) exhibit reversible mechanochromic luminescence (ML). In addition to the mechanism, the effects of arene size, halide substitution, and alkyl chain length have been studied previously. Here, heteroaromatic systems based on thiophene and furan are prepared. Solid-state properties including fluorescence, mechanochromic luminescence and structural data (XRD) will be presented for pristine powders, crystals, and spin cast films.

Mechanochromic luminescent heteroaromatic difluoroboron β-diketonate complexes

249th National Meeting (2015)

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