Design,Synthesis And Application Of Purine Schiff Base Fluorescent Probe

Due to the advantages of simple synthesis,high sensitivity,good selectivity and rapid detection,fluorescent probe method has gradually replaced the traditional detection technology,and has been widely used in various fields such as scientific research and environmental monitoring.Currently,fluorescent probes based on a variety of matrices have been reported,but many fluorescent probes have the disadvantages of high synthesis cost,high biological toxicity,and high detection limit,and there is an urgent need to develop new fluorescent probe matrices.The purine ring is composed of two parts:a pyrimidine ring and an imidazole ring,so it is rich in heterocyclic（N）atoms for metal coordination.More importantly,the biological toxicity of purine and purine derivatives is very low,and it is a new type The fluorophore with great application prospects.Fluorescent probes with Schiff base structure have recently become a research hotspot in this field.The reason is that the structure has outstanding advantages such as simple synthesis and good metal coordination ability,and it has a very wide range of applications in the preparation of fluorescent probes.In this thesis,using the purine ring as the parent,three fluorescent probes with Schiff base structure are designed,and the optical properties and application range of these three probes are studied.The purine ring consists of two parts:the pyrimidine ring and the imidazole ring,so it is rich in heterocyclic（N）atoms that can coordination to metals.At the same time,purine and purine derivatives have little biological toxicity and low price,so they are a new kind of fluorophore with great application prospect.However,at present,there are few studies on the fluorescence probe designed with purine as fluorophore.In this thesis,three kinds of Schiff base fluorescent probes were designed based on purine derivatives and their optical properties and applications were studied.A novel purine Schiff base fluorescent probe WYW was designed and prepared for the detection of Al³⁺.The probe can be rapidly coordinated with Al³⁺in HEPES buffer solution to produce obvious color change,and its selectivity is higher than that of other metal ions.It was found that the WYW-Al³⁺coordination exhibited fluorescence quenching response to F^-by substitution method.Adding Al³⁺to the probe solution has a fast response（within 30s）,and the detection limit is as low as 82 n M.At the same time,the Job’s Plot experiment shows that WYW and Al³⁺are coordinated in a stoichiometric ratio of 1:1,and the coordination method is further confirmed by NMR titration and DFT calculation.In addition,the biocompatibility of WYW and its application in vivo were further confirmed by cytotoxicity and fluorescence imaging experiments.A novel Schiff base fluorescent probe,NPQ,based on purine-quinoline,was designed and synthesized.The probe showed superior selectivity to Cd²⁺and showed obvious color change in Et OH/H2O.Meanwhile,NPQ-Cd²⁺coordinate showed fluorescence quenching response to HPO4^2-by substitution method.Job’s plot,1H NMR and density functional theory（DFT）fully proved the binding mode of NPQ and Cd²⁺.The addition of Cd²⁺to the probe solution showed a rapid response（within 30s）,and the detection limit was as low as41 n M.Most importantly,NPQ has been shown to recognize Cd²⁺in environmental and biological systems through practical applications such as dipsheets and cell imaging.A Schiff base fluorescent probe（PHM）based on purine-vanillaldehyde was designed and synthesized.The probe PHM can quickly identify Pd²⁺and Cu²⁺in DMSO/H2O buffer solution,and then fluorescence quenching occurs.The probe has excellent anti-interference performance and is unaffected by other metal ions in the process of recognizing Pd²⁺and Cu²⁺.The limits of detection of Pd²⁺and Cu²⁺by PHM were 250 n M and 209 n M,respectively.At the same time,the coordination ratios of Pd²⁺and Cu²⁺of probe PHM were determined to be 1:2 and 1:1,respectively,by Job’s plot.Most importantly,the probe PHM can detect Pd²⁺and Cu²⁺in the environment in a solid state form.