The Design,synthesis And Application Of Novel Water-soluble Fluorescent Probes

With the continuous development of the social economy and the people’s growing needs for a better life,the negative problems are becoming more and more serious.Among them,the impact of heavy metal ions,toxic anions and biomolecules on people’s life can not be underestimated.They will harm people’s health and lead to soil pollution and water pollution.In recent years,the toxic effects of metal ions,toxic anions and biomolecules on the physiological and pathological processes of living systems have aroused extensive research interest,and it is also one of the frontier research fields of chemistry,biology and medicine.Therefore,it is of great significance and potential application value to develop an efficient and reliable analytical detection method to monitor the changes of ion and molecular concentration in the system in real time for environmental monitoring,food safety and early diagnosis of diseases.Fluorescence spectroscopy has been widely used because of its advantages of high sensitivity,good selectivity,short response time,simple equipment,and real-time detection in cells and in vivo.In this paper,carbazole,oligothiophene and phenothiazine were selected as three types of fluorophore groups,and the target fluorescent molecular probe was synthesized by using ninhydrin and salicylate hydrazine as recognition units.Then with the help of ultraviolet absorption spectra and fluorescence emission spectrum,research on metal ions(Al³⁺,Hg²⁺,Cu²⁺),toxic anion（Cl O^–）and the identification of bioactive molecules（N₂H₄）sensor performance,and the sensing mechanism were studied,finally further explore them in real water samples,food samples,the efficient real-time detection in the biological sample and the application in biological imaging visualization in living cells.The specific work is as follows:（1）A novel carbazole-indenedione red luminescence fluorescence sensor CBI was developed.This sensor has typical and interesting aggregation-induced emission（AIE）characteristics in a mixed water medium,and has a large Stokes shift.As a colorimetric and fluorescent sensor for detecting hydrazine in pure water,CBI has ultra-sensitive,high selectivity and high sensitivity,with a detection limit of 37 n M.The high sensitivity mechanism of CBI to hydrazine was confirmed by fluorescence spectrum,FTIR,¹H NMR and HRMS spectrum.What’s interesting is that CBI can not only sensitively detect N₂H₄in water,human urine and living cells,but also visually recognize gas N₂H₄based on filter paper strips by visually changing the color of the naked eye.In addition,due to its strong fluorescence under UV light,CBI has been widely used as a writable fluorescent display material as well as fluorescent ink for writing and drawing.（2）Based on carbaldehyde and 2-hydroxybenzohydrazide units,a simple new carbazole Schiff base（CBS）with typical aggregation-induced emission enhancement（AIEE）characteristics was designed and synthesized.Based on the chelation mechanism between the probe CBS and metal ions,the probe CBS showed highly selective colorimetric and fluorescent double response to Hg²⁺and Al³⁺,and showed fluorescence“off”and“on”response to Hg²⁺and Al³⁺in nearly perfect aqueous medium,respectively.The low detection limits of CBS for Hg²⁺and Al³⁺are determined to be 14.7 n M and 47.2 n M,respectively,which are far lower than the WHO drinking water standard,and it indicates that the probe can be used for nano-scale measurement in real samples.Compared with other related chemosensors,the sensor CBS shows many outstanding advantages in Hg²⁺/Al³⁺detection:high selectivity,high sensitivity,good reversibility,fast response,strong anti-interference ability and low cytotoxicity and so on.Using Job’s plot analysis and fluorescence titration curve,the complex stoichiometric ratio between CBS and Hg²⁺/Al³⁺was determined to be 1:1,which was further confirmed by FTIR and¹H NMR analysis.Due to its good colorimetric/fluorescence characteristics,a simple,cost-effective and portable real-time test strip has been developed,which can detect Hg²⁺/Al³⁺intuitively,quickly,reliably and conveniently in environmental analysis.In addition,the CBS has been successfully applied to the construction of molecular logic gates.The results show that the probe CBS can not only achieve high sensitivity on-site detection in the environment and food system,but also can carry out fluorescence imaging visualization application detection of biological processes at the molecular or cellular level,which has important reference value for promoting the application of high-performance new fluorescence probe biological imaging in biological analysis.（3）A novel bifunctional fluorescent probe TSC based on thiophene was designed and synthesized,and it can quickly detect aluminum ions(Al³⁺)and copper ions(Cu²⁺)in pure water.Through the study of its properties,we found that the probe has the advantages of high selectivity,strong anti-interference ability,wide p H response range,high sensitivity(detection limit for Al³⁺:9.98 n M;Cu²⁺:14.3 n M),the stability of the high(association constants for Al³⁺:1.07×10⁴M^-1;Cu²⁺:1.79×10⁴M^-1)and good reversible response in spectral recognition and biosensor performance.Meanwhile,the sensing mechanism of TSC was studied by infrared FTIR and NMR,and the results showed that the stoichiometric ratios of TSC-Al³⁺and TSC-Cu²⁺were 1:1.Based on the good sensing performance of the probe,the colorimetric and fluorescence responses of the probe loaded on the filter-paper,silica gel powder and TLC plate were tested.The excellent performance of the probe can be observed more intuitionistic.In addition,TSC can be used to detect aluminum(Al³⁺)and copper(Cu²⁺)ions in water and food samples by means of probe detection in various environmental aqueous solutions.Finally,based on the excellent reversibility of the probe,a molecular logic circuit was constructed,which proved its wide practicability.（4）A novel red fluorescent ratio probe PD based on phenothiazine was designed and synthesized.The probe can realize the efficient and rapid detection of Cl O^–in（DMSO/H₂O=1:3,v/v）medium.By means of ultraviolet spectrum and fluorescence spectrum,it is found that the probe PD has good sensing properties for Cl O^–,such as high selectivity,excellent anti-interference ability,high sensitivity（47.4 n M）,wide p H range（4-12）,instantaneous response,etc.In addition,based on the excellent colorimetric and fluorescence response of the probe,the real-time and visual applications of the probe itself and Cl O^–detection were realized by using filter-paper and TLC plate as the load.What’s more,probe PD has been successfully used in the detection of Cl O^–in real water samples,which further reflects its application potential.