Design,Synthesis,Characterization And Properties Of Three Fluorescent Molecular Probes

Molecular probe is a tool that can transfer the molecular recognitionevents into the optical signals.Because of its high sensitivity,specific selectivity,simple operation,low cost,free from outside influence of electromagnetic fields,distant luminous and other advantages,fluorescent probe is widely used in pharmaceutical,chemical,biological sciences and other fields.In this thesis,fluorescent probes for 2,4,6-trinitrofenol（TNP）,hydrogen sulfide were synthesized respectively.As follows:（1）Two kinds of fluorescent probe molecules for the detection of 2,4,6-trinitrophenol（TNP）were designed and synthesized.Diethyl benzo[c]cinoline-3,8-dicarboxylate（P1）and benzo[c]cinoline-3,8-dicarboxylic acid（P2）were synthesized via the simple,new and environmentally friendly method,4,4’-biphenyldicarboxylic acid was used as the raw material.The structure of P1 and P2were characterized by mass spectrometry（MS）,¹H NMR,¹³C NMR,elemental analysis and X-ray single crystal diffractometer.The optimum reaction conditions were screened out by a series of comparative experiments.Furthemore,the possible reaction mechanism is deduced from the relationship between the reaction conditions and the yield,as well as the single crystal structure of the intermediate D.Fluorescence spectra showed that probes P1 and P2 have a identification effect on TNP in V_H2O:V_CH3CN=9:1 and V_H2O:V_DMSO=9:1 systems and have high selectivity and sensitivity,the detection limit of the probes P1 and P2 are calculated to be 0.95μM for TNP,1.65μM for TNP.Probe P1 has a better efficiency towards TNP than probe P2.In order to investigate the mechanism of the fluorescence quenching of TNP to probe P1,the possible mechanism of photoinduced electron transfer（PET）was deduced based on the calculated results.The results show that probes P1 and P2 have practical significance in the practical application of TNP in water samples by testing different water samples and light stability.（2）Design and synthesize a fluorescent probe molecule for the detection of H₂S in water.Probe（P3）was synthesized by using 4,4’-biphenyldicarboxylic acid as the starting material,and the structure of the probe was characterized by ¹H NMR,¹³C NMR,MS and elemental analysis.The carbethoxy and azide groups of the probe molecule are electron-withdrawing groups,and the electronic effect of push-pull is weak,so the fluorescence intensity is weak.When the probe（P3）interacts with hydrogen sulfide（H₂S）,the azido is reduced to amino,and the amino is strong electron-donating group,therefore,intramolecular chargetransfer（ICT）and the fluorescence intensity are enhanced.Fluorescence spectra showed that the probe P3 has a ratio-type response to H₂S and P3 has high selectivity and sensitivity to H₂S,it also had strong anti-interference ability and a good fluorescence response in a wide p H range,the detection limit of H₂S was estimated to be1.07×10^-6 mol·L^-1.Through the test of three different water samples,it is indicated that the probe P3 in the detection of H₂S in water has application significance.