Takeda Minakata and co-workers reported tricolor mechanochromic luminescence of phenothiazine-dibenzo[a,j]phenazine-phenothiazine (PDPP) molecules at aggregated states (Figure ). The as-synthesized crystals were yellow-emissive (λmax = 568 nm). Upon grinding, the emission peak of the amorphous powder was red-shifted to 673 nm. After recrystallization from hexane/CHCl3 (3:1) or CH2Cl2, the amorphous powder could resume the original crystals. Moreover, different treatments on the amorphous PDPP powder could result in other polymorphs. Heating could lead to a red-emissive crystalline powder (λmax = 646 nm) while fuming with the CH2Cl2 vapor would produce an orangeemissive crystalline powder with a peak at 596 nm. Single-crystal X-ray diffraction analysis and theoretical calculations revealed that the conformational flexibility of the two phenothiazine moieties should account for the multi-color emissive transformations.