Optical properties and mechanofluorochromism of new BODIPY dyes based on the pyridine–pyrimidine hybrid structure

, 0.11-0.26). X-ray structure analysis demonstrates that H-aggregation should be responsible for the red-shifted and quenched emission in the solid state. Moreover, PPB1-4 show high contrast and reversible mechanochromic fluorescence based on the proposed mechanism of mechanical stimuli triggered dimer dissolution and formation. In addition, rewritable mechanochromic fluorescence recording media fabricated with PPB4 have been successfully achieved.