Synthesis And Properties Of Novel Cyanostilbene Fluorescent Probes

In recent years,the rapid detection and specific recognition ability of fluorescent probes have attracted the attention of many researchers.Traditional fluorescent molecules are prone to fluorescence quenching in aggregated or solid state,which greatly limits their practical application in aqueous phase.The discovery of aggregation-induced emission（AIE）provides a new idea to solve this problem.Cyanostilbene（CS）is one of the star molecules with AIE effect,it has the characteristics of simple structure,high fluorescence quantum yield and good chemical stability.It has shown broad application prospects in the fields of fluorescent probe materials,cell imaging,organic photoelectric materials,liquid crystal materials and photocatalytic materials.At present,many reports have focused on the synthesis and recognition performance of cyanostilbene fluorescent probes,but most of the recognition is carried out for ions,especially metal cations.There are few reports on the recognition of organic functional molecules with complex structures,such as some harmful pesticide molecules and pharmaceutical molecules with special functions.Based on this,several novel cyanostilbene fluorescent probes designed and developed in this study were applied to the identification of pesticide molecules and pharmaceutical molecules,which made a good expansion in this field.In this paper,the cyanostilbene molecule is used as the basic unit,the solubility was improved by introducing alkyl chain and crown ether chain,and the chiral transfer between AIE molecules was explored by introducing chiral groups,four fluorescent probes were obtained.Fluorescence spectrometer,mass spectrometer,ultraviolet-visible spectrometer,nuclear magnetic resonance spectrometer,infrared spectrometer and other instruments were used to study their chemical structure and photophysical properties.The product molecules can have good specific recognition ability for certain ions and molecules.The contents are as follows:Ⅰ.The aminopyridine structure was introduced into the cyanostilbene unit to synthesize cyanostilbene probe derivatives.Through the study of the sensing ability of various molecules,it was found that it had good specific recognition ability for ursolic acid.The fluorescence intensity increased with the increase of ursolic acid content,and the maximum emission wavelength shifted blue.The prepared TLC plates and seal patterns successfully verified that the probe had good detection ability in practical applications.Ⅱ.The fluorescent probe of alkyl-bridged cyanostilbene derivatives was designed and synthesized.The property study showed that the compound had good AIE characteristics,and it was found that it had good specific recognition ability for indoxacarb.After pesticide identification,the fluorescence was enhanced and red-shifted,with the detection limit of5.71×10^-8mol/L.It shows that the probe has good application prospect in pesticide detection.Ⅲ.A crown ether bridged cyanostilbene derivative fluorescent probe was designed and synthesized.The structure was confirmed by NMR and MS,and the fluorescence test showed that the compound had good AIE characteristics.The fluorescence intensity of different water content increases first and then decreases,which is caused by excited state intramolecular proton transfer.In different ion recognition experiments,it is found that it has good specific recognition function for Al³⁺.With the increase of Al³⁺concentration,the fluorescence color changed obviously.Ⅳ.Alkyl-bridged cyanostilbene chiral fluorescent probes were designed and synthesized.The chiral group was introduced to make the chiral transfer to the AIE backbone,and it was found to have good specific recognition ability for oleanolic acid by testing the recognition properties in different molecules and ions.CPL and CD tests showed that the signal of this molecule is strong and the strongest signal in the solid film,which is expected to solve the problem of weak signal in circularly polarized luminescence of aggregation-induced emission materials.