Design, Synthesis and Properties of High-contrast Cationic Mechanofluorochromic Materials

High-contrast organic mechanofluorochromic materials have potential applications in security ink and memory devices, but the mechanochromic materials with luminescence change over 100 nm are still limited. In this work, we designed a D-pi-A organic molecule with large dipole moment N,N-diphenyl-4-[2-(quinolin-2- yl)]aniliue hydrochloride(QV-TPA-HCl), and performed Polymorph for the design molecule. Polymorph indicated that it had the potential to form both monomer and pi-pi stacked cluster. Single crystal structure proved the formation of pi cluster. Upon alternative grinding at 30 degree celsius and 100 degree celsius, Near-infrared fluorescence(673 nm) and green lumines cence(490 nm) could be obtained with luminescence difference 183 nm, due to the reversible conversion between the pi cluster and monomer. Our investigation presents a rational strategy for designing high-contrast mechanochromic materials with significant luminescence change.