Pressure-induced fluorescence enhancement and highly sensitive color change of anthracene-introduced phenacene derivatives in solid state

Exploring functionalities under high-pressure conditions represents a promising frontier in materials discovery. Because molecules in organic crystals form packing structures through weak intermolecular forces such as van der Waals interactions, their intermolecular distances can readily adjust in response to compression. In most luminescent π-conjugated molecules, this compression typically enhances nonradiative decay pathways, resulting in reduced emission intensity. Here, however, we report that applying pressure to single crystals of a phenanthrene-based derivative introduced with anthracene units yields an unusual pressure-induced emission enhancement up to about 1.5 GPa. Furthermore, as pressure increases to 3.5 GPa, the emission peak exhibits a large red shift, by 131 nm, corresponding to an exceptionally high-pressure sensitivity of 37.4 nm/GPa. This sensitivity is the largest value among molecular materials to date.