Temperature-driven molecular dynamics initiate thermochromism and luminescence modulation in an anthracene-based organic semiconductor crystal

We introduce the thermochromic ability of 9,10-bis((E)-2-(pyridin-4-yl)vinyl)anthracene (BP4VA), an organic semiconductor (OSC) employed in optoelectronics. Specifically, crystals of BP4VA undergo a change in color and fluorescence intensity upon the addition of heat. Rationale is provided by variable temperature single-crystal X-ray diffraction (VT-SCXRD) experiments using synchrotron radiation, which revealed detailed molecular and supramolecular rearrangements in the crystal. Increasing temperature results in variations of distance and twist angle between aromatic rings and intramolecular pedal motion, in combination with changes in intermolecular geometries of anthracene cores. Analysis of surface topographies of crystals before and after stimulus is provided by scanning electron microscopy and cross-polarized electron microscopy. Our work shows the potential of temperature-induced property modulation in OSC materials.