Multiple responses of 1,6-diphenyl-1,3,5-hexatriene to mechanical stimulation: emission enhancement, piezochromism and negative linear compressibility.

The properties of mechanoresponsive materials are mainly affected by intermolecular interaction, in which anisotropic grinding and hydrostatic high-pressure compression are the powerful tools used for modulation. Upon applying high pressure to 1,6-diphenyl-1,3,5-hexatriene (DPH), the reduced molecular symmetry results in the originally forbidden S → S transition to become allowed that then leads to a 13-times emission enhancement, and π-π interactions result in piezochromism (red-shifted up to 100 nm). With increasing pressure, high-pressure-stiffened H⋯C/C⋯H and H⋯H interactions enable the DPH molecules to generate a NLC mechanical response (9-15 GPa) with = -5.