Syntheses And Characterizations Of Salamo-Type Fluorescent Chemosensors And Complexes And Their Applications In Environmental Detection And Anticancer Activity

Due to human's unreasonable exploitation of natural resources and arbitrary discharge of toxic substances,a large number of pollutants have appeared in the environment.These pollutants can easily diffuse into water,soil or air,and remain for a long time,which is"pseudo-persistent".What's more serious is that these pollutants can enter the organism through the food chain.These pollutants pose a threat to human health even at relatively low concentrations due totheir cumulative and magnifying effects in organisms.Studies have confirmed that some important diseases,such as tumors and the nervous system,are associated with pollutants in the environment.Therefore,the development of advanced detection methods to detect and monitor environmental pollutants is a prerequisite for clarifying pollution sources,studying the mechanism of pollutants,predicting the pollution process,solving environmental problems,improving environmental conditions,and protecting human health.Compared with other analytical methods,fluorescence analysis has become the most effective and commonly used method to analyze and track target pollutants dueto its high sensitivity,rapid detection,high accuracy and strong anti-interference ability.Salamo-like compounds have shown potential applications in the field of catalysis and sensing due to their good stability,easy optimization of structure,controllable preparation process and strong coordination ability with metal ions.Based on this,in this thesis,two semi-Salamo-like monooxime ligands were preparedby derivatizing the molecular structure of salamo-like compounds.Subsequently,the corresponding complex and coordination polymer were synthesized by the coordination of the two ligands with copper?II?ions,respectively.Meanwhile,the application of these complexes in cancer treatment was investigated.In addition,six types of Salamo-like fluorescent chemical sensors with specific structures were prepared,and their applications in environmental pollutant analysis detection and environmental remediation were studied.The research content of this thesis is divided into the following six parts:?1?The single crystal structure of the copper?II?complex[Cu₂?L¹?₂??-OAc?₂]of a semi-Salamo-like ligand HL¹was first reported.Research on crystal structurefound that the copper?II?complex was self-assembled through intermolecular hydrogen bond interactions to form a three-dimensional supramolecular configuration extending infinitely inward.Experiments to simulate cellular microenvironment have proved that the copper?II?complex can reduce GSH levels,improve tumor microenvironment,and has synergistic enhanced chemodynamic therapy?CDT?effect.Cytotoxicity studies showed that the copper?II?complex could achieve effective killing of hela cells at very low concentrations.?2?A new ligand HL³,which was formed through Cu?II?catalytic breaking of O-N bond of a ligand HL² as the precursor,reacted with copper?II?acetate to obtain a copper?II?coordination polymer_?[Cu?L³?].The vitro experiments showed that the copper?II?coordination polymer could be decomposed and reduced by GSH in the tumor microenvironment to obtain Cu?I?.The Cu?I?reacted with overexpressed H₂O₂in tumor cells to generate a hydroxyl radical,thereby increasing intracellular ROS levels and achieving a highly efficient CDT.This study provides a new strategy for the development of Salamo-like coordination polymer as a potential anticancer drug to enhance CDT.?3?For the first time,an asymmetric single-Salamo-like fluorescent probe G1was synthesized and used for highly selective detection of borate and formaldehyde.The detection mechanism is that the coordination reaction between G1and borate closes the excited intramolecular proton transfer?ESIPT?process of G1,thereby achieving the ratio detection of borate.In addition,G1 can be used to detect and determine the content of borate in polluted water bodies and soils,so it has a good application prospect in industrial wastewater monitoring.Interestingly,the complex G2 formed by G1 and borate can be used for fast,highly selective and sensitive detection of HCHO contaminants.The detection mechanism is to induce the removal of boronic acid groups of sensor G2 through the Cannizzaro disproportionation reaction,triggering the"activation"of the Salamo-like sensor fluoropHore.Sensor G2is stable in air and water,while detecting formaldehyde,the toxic formaldehyde is further converted into low toxic compounds.Experiment results show that sensor G2can be used to analyze formaldehyde pollutants in frozen food and water.The research work in this part also proves that our designed asymmetric single-Salamo-like fluorescent chemical sensor can convert pollutants to eliminate pollution,which has a great application prospect in environmental remediation.?4?For the first time,the semi-Salamo-like sensor G3withsingle-excitation and dual-emission was used for highly sensitive detection of H⁺in the range of pH=2?11.The detection mechanism of sensor G3 is based on the fact that its molecule exhibits different tautomeric configurations at different pH environments,thereby OFF or ON the ESIPT process,and enabling ratio sensing in pHysiological pH environments.In addition,the luminescent salamo-like napHthalene-based sensors G3 contains a N₂O₂coordination cavity that can coordinate with Cu²⁺ions,which can achieve high selectivity and high sensitivity to identify Cu²⁺ions,with detection limit 2.4×10^-12mol/L.At the same time,sensor G3 can detect Cu²⁺ions in actual water samples including tap water and yellow river water.To improve the application convenience of the sensor,the test strip of the load sensor G3 was prepared,which could be applied to the convenient,fast and accurate detection of Cu²⁺ions in actual water samples.In addition,the recognition process of Cu²⁺by sensor G3 can be applied in the field of anti-counterfeiting,which will greatly expand the application potential of sensor G3.?5?A semi-Salamo-like fluorescence sensor G4 was firstdeveloped to specifically recognize arginine?ARG?and glutathione?GSH?,in which Arg enhances the fluorescence of the sensor,and GSH quenches the fluorescence of the sensor.Sensor G4 is also the first Salamo-like fluorescent small molecule sensor that can detect Arg in an aqueous system.The study found that different substituents in sensor G4 played an important role in molecular recognition.Experimental and quantum chemical theoretical calculations have confirmed that sensor G4 and Arg formed a 1:1 complex,which can be used for the determination of Arg in food and medicine.Sensor G4 has two potential active sites in the structure,which can distinguish GSH from Cys/Hcy,thus establishing a new strategy for identificationofbiothiol.The interference to GSH in the presence of Cys and Hcywas eliminated by using the subtle differences in the structure of three thiols and the two specific binding active sites in G4,which provided the possibility for the fluorescent discrimination and recognition of three thiols.Meanwhile,such method is fast,simple,and economical,and sensor G4is less toxic,which can be further extended to the p Hysiological environment detection.This part of the research work also proves that the designed semi-salamo-like fluorescent sensor G4 has obvious advantages in sensitivity and selectivity,and is expected to be used in early diagnosis of diseases.?6?A Salamo-like fluorescence sensor G5 was synthesized,and its high sensitivity and rapid recognition of ClO^-and SCN^-were achieved through the cleavage and generation of Schiff base?imine?bonds in its molecular structure.Based on the intramolecular charge transfer?ICT?as the signal mechanism,the sensor achieves the ratio fluorescence response to ClO^-and SCN^-by changing the push-pull ability of electrons,respectively.The experimental results show that the sensor can achieve ratio detection of the ClO^-and SCN^-in real water samples?tap water and Yellow River water?,respectively.Based on the redox reaction between ClO^-and SCN^-,while detecting the polluted ions in the environmental system,the sensor can also degrade the pollutants in water through chemical reactions without affecting the environment.Compared with other types of sensors,the single Salamo-like fluorescence sensor G5 has the advantages of simple synthesis,good selectivity,high sensitivity,easy operation,fast response time and reusability.