Multi-stimuli responsive behavior by a simple donor-acceptor type acylhydrazone based crystal

In this manuscript, we report a novel diphenylamine-acylhydrazone based compound namely (E)-N ' -(4- (diphenylamino)benzylidene)-4-hydroxybenzohydrazide ( DPAhydrzOH ) which showed multi -stimuli responsive behavior by displaying pronounced mechanochromic luminescence (MCL), thermochromic luminescence and photomechanical effect in solid state. Single crystal structure of the compound revealed that the molecule is tied with different types of H -bonding interactions. Detailed mechanistic study suggests that the MCL switching in solid crystal is rooted to the shear pressure induced structural rearrangement. The captivating photomechanical effect in the crystal was expressed in the form of cracking, small movement under 365 nm light due to photoinduced trans to cis isomerization in solid state.