Multi-stimuli responsive fluorescence switching: the reversible piezochromism and protonation effect of a divinylanthracene derivative

A novel divinylanthracene derivative 9,10-bis((E)-2-(pyridin-4-yl)vinyl)anthracene (BP4VA) was synthesized and its two polymorphs with different crystal structures were obtained. The introduction of pyridine in BP4VA leads to multi-stimuli responsive fluorescence. An investigation of the photophysical and stimuli responsive luminescent properties of BP4VA, including the piezochromism and protonation effect, demonstrates that the piezochromic luminescence originates from changes in the molecular aggregation state. Additionally, protonation–deprotonation of the pyridine moieties in BP4VA has a significant effect on the frontier molecular orbitals, resulting in distinct green and red emissions under acid and base stimuli. This study on BP4VA provides a comprehensive insight into the mechanisms within this type of stimuli-responsive luminescent material, and suggests that BP4VA may be a potential candidate for applications in sensing, detection and display devices with remarkable color-changing properties.