Synthesis And Properties Of Fluorescence Probe Molecules Of Dibenzoylhydrazone Coumarin

Biogenic amines（BA）are generally produced from the degradation of amino acids in biometabolism,which can be used as an important biomarker for food spoilage and various diseases.The developing of rapid,simple and accurate methods for detecting biogenic amines is significant and imperative due to the growing food safety problems and health concerns.Although a variety of detection methods for amine vapors have been reported,such as gas/liquid chromatography,electrochemical systems and colorimetric arrays,most of them have a series of limitations,including complex components,large stationary instruments and time-consuming analysis process.Accordingly,it is hugely desirable to develop the simple fluorescent sensors for amine vapors detection with the excellent accuracy,short analysis time,easy visualization and simple operation.In this paper,we first synthesized a series of bisbenzoylhydrazone coumarin（BDCH）fluorescent compounds.After separation and purification,the series of compounds were characterized by ¹H NMR,¹³C NMR and EI-MS and the structure of the compounds were confirmed to be correct.Secondly,we studied the selective recognition of metal ions by the compound BDCH₂.By testing the UV absorption and fluorescence emission spectra of BDCH₂with different metal ions in the DMF/H₂O mixed system,we found that the compound BDCH₂ has a specific recognition effect on Cu²⁺,and proposed the mechanism of BDCH₂ with metal ions.Then,we studied the aggregation-induced fluorescence emission shift（AIES）properties of BDCH compounds.By testing the fluorescence emission spectra of BDCH compounds in different concentrations of THF solutions,we found that with the concentration（1μM-1 m M）of BDCH compounds increased,the fluorescence emission peak was red-shifted.In addition,with the length of the alkyl chain increased,similar enhanced emission was also observed.This appearance showed that the fluorescence emission peak shift of BDCH compounds was not only related to the concentration of the solution,but also affected by the length of the alkyl chain.This may be caused by the enhancement ofπ-πinteraction and hydrogen bond interaction with the concentration increased.Finally,we studied the color change behavior of BDCH compounds in response to stimuli.After HCl fumigation,the fluorescence emission peak of BDCH compounds red shifted,and after NH₃ fumigation,the fluorescence emission was significantly blue-shift.In order to further explore the reversibility of the protonation and deprotonation process,we tested the X-ray diffraction（PXRD）and ¹H NMR of the three samples,and found that the hydrogen protons interact with the nitrogen atoms on the diethylamino group.And the transition between the protonation and deprotonation process was completely reversible and scatheless in actually.We believed that the red shift of the fluorescence emission peak situation was due to the enhanced electron withdrawing ability of the protonated diethylamino group and the delocalization of electrons causes a reduction in the energy band gap.Based on the good reversible stimulus response of the compound BDCH₂,we used the compound BDCH₂as a smart label for real-time monitoring of the freshness of aquatic products.The results showed that it could quick,real-time and visually monitor the freshness of aquatic products,so BDCH₂ had potential application value as an ammonia sensor.