Synthesis And Properties Of Fluorescent Probes For Cyanide Detection Based On Barbituric Acid

With the development of industry,human and society,environmental pollution is increasing,a large number of heavy metal ions and toxic anions are discharged into the atmosphere,soil and water body,causing disease,irreversible damage and even death to human body.Due to the advantages of simple recognition and good reactivity,fluorescence analysis has been widely used in the detection of heavy metal ions and toxic anions in recent years.The contents are as follows:A new carbazole-based naked-eye colorimetric and fluorescent sensor CPPB with aggregation induced emission?AIE?effect was successfully synthesized.The solid powder of CPPB emitted intense yellow fluorescence,and its emission wavelength and fluorescence intensity in DMSO/H₂O solution varied with the percentage of water?f_w?.Nano-aggregates of CPPB molecules were prepared by increasing fw of DMSO/H₂O solution,and the optimal aggregation state of CPPB was reached in 99%aqueous DMSO solution with the maximum fluorescence intensity.Moreover,CPPB displayed high selectivity and sensitivity toward cyanide anions?CN^-?in 99%aqueous DMSO solution even in the presence of other competitive anions.The sensing mechanism for CN^-was confirmed by optical spectral studies,¹H NMR titration,HRMS spectra,Job's plot analyses and DFT calculations.Sensor CPPB for CN^-detection revealed extremely low detection limit?67.4 n M?,high anti–interference ability,wide p H response range?3.0–10.0?as well as the immediate response?15 s?.Furthermore,the CPPB-based test strips were applied to detect CN^-qualitatively and quantitatively in 100%aqueous solution.A new dibenzothiophene-based barbituric acid derivative?DTB?with an aggregation induced emission?AIE?effect was synthesized as a naked-eye colorimetric and fluorescent probe for CN^-.The UV-vis spectra and fluorescence spectra of DTB in a DMSO/H₂O mixture changed with different water fractions?f_w?.Nanoaggregates of DTB were formed with the strongest fluorescence emission when fw reached 99%.Furthermore,DTB expressed good selectivity and high sensitivity for CN^-in 99%aqueous DMSO solution.The sensing mechanism of DTB for CN^-was confirmed by ¹H NMR titration,HRMS spectra,Job's plot and DFT calculations.Furthermore,DTB detected CN^-with a low detection limit?21.6 n M?,wide p H range?4–10?,high anti-interference ability and fast response time?10 s?.Moreover,DTB-based test strips were prepared for CN^-detection,and DTB could detect CN^-in real water samples.Based on dibenzothiophene fluorophore,a new colorimetric and fluorescent sensor DTI was developed that was a favorable turn-off fluorescent sensor of monitoring CN^–ion at extremely low detection limit?0.14?M?in 99%aq.DMSO solution.The response mechanism of DTI towards CN^–could put down to nucleophilic attack of cyanide toward the?–conjugated position of the meldrum's acid portion of the sensor breaking intramolecular charge transfer?ICT?process,which was proposed by ¹H NMR,Job's titration and DFT calculation,leading to a significant fluorescence enhancement and a visual color change.The absorption and emission experiments demonstrated that it showed highly sensitive and selective and good stability for CN^–sensing in DMSO/H₂O?1:99,v/v?.Moreover,sensor DTI displayed high effectiveness in monitoring the CN^–in test strips achieved to conveniently determinate CN^–by naked-eye without any instruments.