A diketopyrrolopyrrole-based fluorescent probe DPP-HBT bearing a benzothiazole hydrazone motif exhibited an obvious fluorescent turn-on response toward Pb2+ ions with a low detection limit of 2.3 × 10−10 M in aqueous solution. Furthermore, the imaging experiments indicated that this probe was cell-permeable and could be used to detect Pb2+ ions within living cells.

The isobaric vapor–liquid equilibrium (VLE) data of methyl ethyl ketone (MEK) + sec-butyl acetate (SBAC), 2-methoxyethanol + SBAC, and 1, 2-dimethoxyethane (DME) + SBAC were determined at 101.3 kPa by using an Ellis vapor–liquid equilibrium still. The experimental data passed the thermodynamic consistency test by Herington method and Wisniak test. The VLE values were correlated by the nonrandom two-liquid (NRTL), universal quasichemical activity coefficience (UNIQUAC), and Wilson activity-coefficient models. The results indicated that the three models had good agreement with the experimental data. The 2-methoxyethanol + SBAC system forms a minimum temperature binary azeotrope at 101.3 kPa. The azeotropic temperature is 383.86 K, and the composition of SBAC is 85.1 mol %.

A new colorimetric and on–off fluorescence sensor based on diketopyrrolopyrrole (DPP) was synthesized for detection of fluoride anion. The sensor displayed a rapid responsivity and high selectivity and sensitivity towards F− over other anions, and it also exhibited a very low detection limit of 4.07 × 10−8 M. The signaling process was confirmed by UV-vis, fluorescence measurements as well as 1H and 19F NMR spectroscopy. The experimental results revealed that the formation of anionic species from deprotonation of the hydrazone N–H moiety by fluoride ion was responsible for the spectral changes. Density function theory calculations were conducted to rationalize the optical response of the sensor.

A series of diketopyrrolopyrrole (DPP) derivatives DPPPHs based on phenylhydrazone group were designed and synthesized. The presence of nitro moiety at ortho-position of phenylhydrazone in o-NO2-DPPPH and o,p-di-NO2-DPPPH significantly altered the electronic properties through intramolecular hydrogen bonding. Among these receptors, p-NO2-DPPPH showed excellent selectivity toward fluoride anions in both UV–vis and fluorescence channels in DMSO solution. Experimental results, 1H NMR and 19F NMR revealed that the formation of anionic species from deprotonation of the hydrazone N–H moiety by fluoride ion was responsible for the spectral changes. Density function theory calculations were conducted to rationalize the optical response of sensors. Especially, the spectral responses of sensors could be switched back and forth alternatively by adding F− and HSO4− anions in DMSO solution.