Acid-induced Multicolor Fluorescence of Pyridazine Derivative.

Smart luminescent materials that are responsive to external stimuli have received considerable attention. Here we report a new D-A type 1,2-pyridiazine derivative (TPP) exhibiting turn-on fluorescence upon acid both in solution and in solid state. The protonation of the 1,2-pyridiazine ring caused a variation in the emission colors of the acidification species from blue (406 nm) to orange-red (630 nm) with a huge Δλem (224 nm). As a result, a synthetic rainbow of emission in solution could be achieved from one single molecule, and white photoluminescence was readily tuned by controlled protonation. A TFA-sensor film made from TTP was demonstrated as a TFA-sensitive surface with high sensitivity and reversibility. On the basis of these findings, we constructed a solid state TTP film with a photoacid generator and demonstrate data encryption and decryption via cascade protonation reaction well controlled by UV light.