Investigation Of Fluorescent Chemosensors For HClO And Cu²⁺

Hypochlorite and copper ions are important chemical substances,which have significant effects on physiology and environment.The imbalance of hypochlorite and copper ions in vivo will lead to various diseases and affect people's health.Therefore,the design and development of new fluorescent probes with high sensitivity and selectivity is of great significance for the detection of hypochlorite and copper ions in physiological and environmental systems.Based on different mechanisms,three fluorescent probes were designed to detect hypochlorite and copper ions,respectively Based on the above content,this paper is mainly divided into four chapters,the content is as follows:The first chapter is an introduction,which mainly introduces the related concepts and design principles of optical molecular sensors,the mechanism of fluorescent chemical sensors,the research status of hypochlorite and copper ion fluorescent sensors,and puts forward the ideas and objectives of this paper.In the second chapter,based on the condensation reaction of Dansyl hydrazide with ferrocene formaldehyde,a Schiff base Dansyl fluorescent probe was designed and synthesized.Fe2+ in ferrocene group was oxidized to Fe3+after the interaction of probe molecule with HClO,which inhibited the PET process from ferrocene to Dansyl fluorophore,resulting in the enhancement of fluorescence at 497 nm.The detection limit is as low as 7.9×10-9 mol/L,and the method also showed high selectivity.The "OFF-ON" fluorescence response with high sensitivity to hypochlorite in a wide pH range can be realized.In the third chapter,a FRET fluorescent probe was synthesized based on the condensation reaction of spiro rhodamine B hydrazide and fluorescein isothiocyanate.The fluorescence ratio of hypochlorite can be determined by the fluorescence ratio at 593 and 525 nm.The interaction with HClO causes the ring opening of spiro rhodamine B hydrazide,which realizes the fluorescence resonance energy transfer from fluorescein to rhodamine.At the same time,the color of the solution changes from yellow to pink.In addition,the probe molecule responds quickly,and can produce color changes in about 3 minutes.It has good selectivity for HClO,and realize naked-eye and ratiometric fluorescence recognition of HCIO under physiological pH conditions.In chapter 4,based on heptamethylene cyanine dyes,a visible-NIR(near infrared)ratiometric fluorescent probe for high sensitivity detection of copper ions was synthesized.The fluorescence ratio(F552nm/F790nm)of the probe increased significantly after interaction with copper ions,which was about 150 times larger than that of the blank probe solution,and copper ions could be specifically identified in the solution under physiological pH conditions.Meanwhile,the color of the solution changed significantly before and after the interaction of the probe with Cu2+,therefore,the naked-eye recognition and sensing of Cu2+ can also be realized.