A red-emission diketopyrrolopyrrole-based fluoride ion chemosensor with high contrast ratio working in a dual mode: Solvent-dependent ratiometric and “turn on” pathways

A new diketopyrrolopyrrole derivative (DPP-4) with two triphenylamine groups was developed as red emission fluorescent sensor for fluoride ion. The fluorescent changes of DPP-4 interact with fluoride ion exhibiting obvious solvent-dependent properties. In acetone, ratiometric channel was activated upon addition of n-Bu4NF, and more than 50 nm red shift from 590 nm to 641 nm was obtained and accompanied with emission color from orange to purple red. In acetonitrile, addition of fluoride caused 50-fold enhancement at 631 nm in emission spectra which be defined as a “turn on” mode. Interestingly, using fluoride and HSO4− anions as two chemical inputs and absorption or fluorescence as output, compound DPP-4 is demonstrated to be a parallel double-INH logic gate in acetonitrile solutions.