Perfluorophenyl-Bifuran: A Stable and Fluorescent Material Exhibiting Mechanofluorochromic Behavior

π-Conjugated oligomers and polymers consisting of bifuran units are applied in optoelectronic devices, because bifuran units endow such devices with superior properties compared with their thiophene analogs. However, as is true for most furan oligomers, bifuran oligomers suffer from low photostability, which restricts their application. In this work, we present the synthesis and the photophysical and structural characterization of perfluorinated phenyl bifuran (PFB-2F), which displays high photostability, while maintaining strong fluorescence quantum efficiency in both solution and the solid state. X-Ray crystallography reveals that, unlike its thiophene analog, PFB-2F has a completely planar backbone, with slip-stacked packing and short interplanar distances. PFB-2F crystals display mechanofluorochromic behavior, which renders perfluorophenyl-substituted oligofurans potential candidates for both stable optoelectronic devices and responsive optical materials.