Pressure-Dependent Structural and Luminescence Properties of 1-(Pyren-1-yl)but-2-yn-1-one

The crystal structure of 1-(pyren-1-yl)but-2-yn-1-one ([Formula: see text] , a polynuclear aromatic hydrocarbon displaying enhanced luminescence in the solid state, has been re-determined at several pressures ranging from atmospheric up to 3 GPa using a Diamond Anvil Cell (DAC). These experiments were augmented by periodic DFT calculations at pressures up to 4.4 GPa. UV-Vis fluorescence of [Formula: see text] at non-ambient pressures has also been investigated. The crystal structure consists of infinite [Formula: see text]-stacks of anti-parallel [Formula: see text] molecules with discernible dimers, which may exemplify aggregates formed by pyrene derivatives in solution and thin films, and is predominantly stabilized by dispersion. The average inter-planar distance between individual molecules within [Formula: see text]-stacks decreases with pressure in the investigated range. This results in piezochromic properties of [Formula: see text]: a red-shift of sample color, as well as a bathochromic shift of fluorescence with pressure (by ca. 100 nm at 3.5 GPa). Two-component fluorescence spectra support the hypothesis that at least two types of excimers are involved in the electronic excitation processes in crystalline [Formula: see text].