Design And Synthesis Of Reactive Hypochlorite Fluorescent Probes Based On Naphthalimide And Research On Their Application

Hypochlorous acid is widely used as a strong oxidant.It is often used as a bleaching agent,disinfectant,and deodorant in life.The chlorination method used in the disinfection of living tap water also depends on the hypochlorous acid generated by the dissolution of chlorine gas in water.The oxidation and deactivation of odorous inorganic substances and natural substances can achieve sterilization effect.However,excessive hypochlorous acid will corrode the pipeline and produce impurities,which poses potential threats to human's health.Hypochlorous acid also plays an important role in the human body.As a kind of active oxygen,hypochlorous acid participates in many physiological processes and plays an important role in the cellular immune process and cellular redox balance.However,studies have shown that abnormal changes in the content of hypochlorous acid in the human body are closely related to various diseases of the body,and the detection of hypochlorous acid content in the body can be used to help monitor the condition of the disease.Therefore,it is of great significance to study real-time,efficient,sensitive and low-cost hypochlorous acid detection methods.In this paper,the fluorescent analysis method widely used in recent years due to its versatility and easy operation is used to study and detect hypochlorous acid in the environment and biological cells.According to the molecular recognition and molecular fluorescence response mechanism,three fluorescent probes for recognition of hypochlorous acid were designed and synthesized with naphthalimide fluorophore as the host.The main research contents are as follows:1.Based on the intramolecular charge transfer mechanism,the electron-donating structure 4-amino-2,2,6,6,-tetramethylpiperidine-1-hydroxy was introduced into the naphthalimide to form D-?-A structure,then the probes NAP-1 and NAP-2 were designed and synthesized.Both the two probe molecules emit fluorescence due to the ICT effect.After the reaction with hypochlorous acid,the fluorescence of the two probes were quenched.The minimum detection limits for hypochlorous acid were 10.03 nM and 2.03 nM respectively,and the response was rapid(completed within 30s),and the hydroxyl group of the recognition group was oxidized to oxygenamine cation.Mass spectrometry analysis confirmed the presence of the product.Using Gaussian to theoretically calculate the products,their front-line molecular orbital distribution indicates that the PET formation process leads to the quenching of the fluorophore's fluorescence,and then the product can be reduced by ascorbic acid to hydroxylamine to restore the probe fluorescence,forming on-off-on reversible fluorescent probes.After 4 cycles,the fluorescence can still maintain more than 80% of the original fluorescence intensity.Fluorescence confocal experiments were carried out on the probe NAP-1.The results showed that the probe NAP-1 can sensitively detect endogenous and exogenous hypochlorous acid in biological cells,and has excellent cell compatibility and low cytotoxicity.2.Based on the photo-induced electron transfer mechanism,maleimide group was introduced into the 4 position of naphthalimide to design and synthesize the off-on hypochlorous acid fluorescent probe NAP-6.The strong electron-withdrawing ability of the maleimide group and the fluorophore constitute the A-?-A system,so the probe NAP-6 has no fluorescence.By oxidizing the double bond on maleimide with hypochlorous acid,the five-membered ring structure of maleimide is opened,the PET process is blocked,and the fluorescence of naphthalimide is restored.The probe has good sensitivity and selectivity to hypochlorous acid,the minimum detection limit is 67.3nM,and the change from colorless to yellow can be observed with the naked eye.There are 64 figures,7 tables,and 107 references in this paper.