Construction And Application Of Terpyridine-based Fluorescent Molecular Probes

With the development of high-tech science and technology in modern society,human beings have more and more demands and influences on the natural world.The ensuing environmental pollution problems have also brought great harm to the natural world and human health.Therefore,various technologies for detecting environmental pollutants and harmful substances in organisms have emerged one after another.Among various detection technologies,fluorescence detection technology is widely used in the detection environment because of its advantages such as high sensitivity,good selectivity,good stability,and simple operation.It can achieve real-time and in-situ detection of analytes.Therefore,it is usually widely used to detect abnormal levels of various molecules and ions in the environment and in vivo.Among various fluorescence detection technologies,fluorescent probes have become a hot research topic in recent years due to their advantages such as high efficiency,convenience,and high reproducibility of detection results.Taking advantage of the strong coordination ability,structural modifiability and stability of terpyridine fluorescent molecular compounds,two different types of terpyridine compounds were designed and synthesized as fluorescent probes for the detection of Cu²⁺,biothiols and HClO respectively,the performance of the two probes was studied.The research work mainly includes:1.A long fluorescence lifetime and multifunctional probe Tpy3 for detecting Cu²⁺and biothiols.Probe Tpy3 based on the mechanism of ligand-to-metal based charge transfer（LMCT）was designed by using the long-lived carbazole benzonitrile derivative D-A type fluorophore as a signal group and using the coordination ability of terpyridine as a recognition group.Probe Tpy3 can specifically recognize Cu²⁺and exhibit quenching of fluorescence and shortening of fluorescence lifetime.Through the indicator replacement method,the complex Tpy3-Cu²⁺generated in situ as a"off-on"type fluorescent probe selectively recognizes biothiols,so that the fluorescent intensity and lifetime of the probe Tpy3 are restored.The process achieves dual detection of Cu²⁺and biothiols.Finally,Tpy3-Cu²⁺was successfully applied to the detection of biothiols in cells.2.A water-soluble probe TpyZnS for detecting HClO.Using the thioether group as the reaction site,the introduction of Zn²⁺increases the water solubility of the probe and adjusts the fluorescence properties of the terpyridine ligand.Based on the intramolecular charge transfer mechanism,the probe TpyZnS can specifically undergo a redox reaction with HClO to oxidize the thioether group to a sulfoxide group,which quenched the fluorescence of the probe TpyZnS.We performed a series of nuclear magnetic characterizations on the probe TpyZnS,including¹H NMR,¹³C NMR and HRMS to confirm the structural correctness.Subsequently,a series of spectral experiments,pH response experiments,time response experiments and density functional theory（DFT）calculations were carried out.Finally,the probe TpyZnS was successfully applied to detect HClO in real water samples and cells.