Construction Of A Column[5] Aromatic Hydrocarbon Fluorescence Sensor And Its Analytical Application

Pillararene are cyclic oligomers of hydroquinone ether or hydroquinone connected by methylene bridge in the benzene,which have highly symmetrical columnar structure and electron-rich cavities.Pillararene are more chemically modified and have better rigid cavities.In this paper,supramolecular fluorescent probes of methyl pillar[5]arene,pyridine pillar[5]arene/naphthol and pyridine pillar[5]arene/acridine derivatives were constructed based on the aggregation induced emission(AIE)effect of pillar[5]arene and host-guest recognition properties of pillar[5]arene.The host-guest interaction and recognition performance of methyl pillar[5]arene on amino acids,pyridine pillar[5]arene/naphthol series supramolecular fluorescent probes on metal ions,anions and pyridine pillar[5]arene/acridine derivatives series supramolecular fluorescent probes on pesticides have been studied,and the detection of non-fluorescent molecules and ions has been realized.The main research contents and results are as follows:(1)The aggregation fluorescence induced by methyl pillar[5]arene in different solvents was studied by its own aggregation fluorescence induced effect.In the mixed solution of Et OH/CH₂Cl₂(98/2,v/v),it was used as a fluorescence sensor for selective recognition of L-Trp.The results showed that the fluorescence intensity of Me P5 decreased significantly after adding L-Trp,but it had no significant change in the 19 natural amino acids.The results of ¹H NMR titration,Mass Spectrometry,Fluorescence Spectra and Theoretical Analysis show that L-Trp enters the cavity of Me P5 and forms an inclusion complex with 1:1 action.(2)The interaction between 1-naphthol and the host and guest of Py P5 was studied by UV-vis absorption spectrophotometry,fluorescence spectra and ¹H NMR titration.The results showed that 1-naphthol entered the cavity of Py P5 and formed a1:1 host-guest inclusion complex(Py P5@1-naphthol).A supramolecular fluorescent probe of Py P5@1-naphthol was constructed in aqueous solution.The results showed that the fluorescent probe specifically responded to Fe³⁺and Ag⁺cation,but did not respond to any other metal cation.Then,the sensitivity of Py P5@1-naphthol probe to different metal ions was investigated by fluorescence spectroscopy and ¹H NMR titration,and the interaction pattern between Py P5@1-naphthol host and guest metal ions was explored.(3)The host-guest interaction between Py P5 and 2-naphthol was studied by UV-vis absorption spectrophotometry,fluorescence spectra and ¹H NMR titration,indicating that the water-soluble pillar[5]arene(Py P5)and 2-naphthol formed a 1:1host-guest inclusion complex.A supramolecular fluorescent probe of Py P5@2-naphthol was constructed in aqueous solution,and different anions were detected by the fluorescent probe constructed.When different anion solutions were added to the fluorescent probe solution,only CO₃^2-would lead to the change of fluorescence emission spectral intensity of the fluorescent probe.The results showed that the Py P5@2-naphthol fluorescent probe had a special recognition effect on CO₃^2-in all anions.The mechanism of Py P5@2-naphthol probe interacting with CO₃^2-was studied by ¹H NMR spectroscopy.(4)A water-soluble acridine derivative(AC)was synthesized and the host-guest interaction between pyridine pillar[5]arene(Py P5)and water-soluble acridine derivative(AC)was studied by UV-vis absorption spectrophotometry,fluorescence spectra and ¹H NMR titration.The results showed that the inclusion complex of 1:1host-guest inclusion complex(Py P5@AC)was formed when AC entered the cavity of Py P5.A supramolecular fluorescent probe(Py P5@AC)was constructed for selective recognition of pesticide molecules.The experimental results show that the probe has the ability to recognize hymexazol and ethiofencarb.The mechanism of recognition of hymexazol and ethiofencarb by the probe Py P5@AC was investigated by fluorescence spectrum and ¹H NMR titration,and the possible mode of action was speculated.