Heating the ground powder to 200 °C also did not result in any change in the photophysics. Powder X-ray diffraction (PXRD) measurements were performed in order to gain deeper insight into the observed mechanochromic behavior of these compounds (Figure ). The PXRD analysis of tBuTPA-BQ showed resolved peaks, indicating the crystalline nature of the sublimed sample. The diffractograms of the ground powder and as-prepared sample did not show any noticeable reflection peaks indicating that these samples are in an amorphous state. These observations demonstrate a morphological transition between the crystalline (ordered) and amorphous (disordered) phases. None of the pure solid samples of tBuTPA-BQ showed TADF as-prepared, sublimed, or ground (Figure ).