Proton-Triggered Hypsochromic Luminescence in 1,1′-(2,5-Distyryl-1,4-phenylene) Dipiperidine

A proton-triggered
hypsochromic luminescent chromophore 1,1′-(2,5-distyryl-1,4-phenylene)
dipiperidine (DPD) was designed and synthesized. Upon treatment by
hydrochloric acid (HCl), the emission of DPD showed a large hypsochromic
shift in both THF solution and microcrystals. Theoretical calculations
and powder X-ray diffraction experiments reveal that the switchable
emission of DPD originated from the change of the distribution and
the spatial arrangement of the frontier molecular orbitals, and the
different stacking modes of DPD in microcrystals also contribute to
the switchable emission of DPD in aggregates.