Design,Synthesis And Application Of Fluorescence Probes For Cascade Detection Of Zn²⁺ And H₂PO₄^-

As the important life activity related ions,Zn2+ and H2PO4-ions play signicicant roles in the metalloproteinase regulation,gene transcription,clinical diagnosis and others.In recent years,numerous fluorescent sensors for the Zn2+ and H2PO4-have been reported.However,novel ratiometric fluorescent sensors for the cascade detection of Zn2+ and H2PO4-is still in highly demand aiming to enhance the utilization of the sensors in environmental detection and biological imaging.This thesis mainly focused on the design,synthesis and biological imaging application of a series novel fluorescent sensors based on the intramolecular charge transfer mechanism(ICT),combing with the theoretical calculation.The research results are summarized below:1.A series of fluorescence recognition group for the cascade detection of Zn2+and H2PO4-had been designed and synthesized through introducing a heterocyclic fragment on carboxamidoquinoline.These new receptors displayed high selectivity,excellent "off-on-off" fluorescence characteristics and good ability for modification.Sensor 2a-5 demonstrated good cell compatibility and have been applied in the living cell image of Zn2+ ions in HeLa successfully.2.We had put forword a new styategy to enhance the detection ability of recognition group(2a-1)through introducing the triazole or alkyne moiety as the electron donor with the help of theoretical calculation.One-pot method had been studied for these fluorescent sensors,and a series of novel sensors for the cascade detection of Zn2+ and H2PO4-had been synthesized under the optimal reaction conditions(3a-1?3a-6,4a-1?4a-7).The results of investigating the propertities of these sensors demonstrated that,compared with 2a-1/Zn2+,the fluorescence emission spectroscopy,fluorescence quantum yield and ratiometric characteristics had been inhanced obviously after modified by triazole or alkyne moiety.Sensor 3a-1 and 4a-1 demonstrated good cell compatibility and had been applied in the living cell image of Zn2+ in A549,HuH7 and HepG2 successfully.3.Based on the research about the methodology and fluorescence performance in previous chapters,several new sensors for the cascade detection of Zn2+ and H2PO4-with targeted cell imaging ability were designed and synthesized through the introduction of two targeting molecules,erlotinib and galactose.The results showed that sensor 5a-1 displayed high selectivity for the EGFR and demonstrated targeted cell image ability for the A549 cells through the introduction of erlotinib moiety with the triazole as the linker,however,the fluorescence signal can not be detected in the HuH7 cells.Then another targeting molecules was introudued onto the sensors which reported in chapter 3 and chapter 4,the water-solubility of the new sensor 5a-2 and 5a-3 were enhanced significantly,and the cascade detection of Zn2+and H2PO4-could be conducted in pure water.5a-2 and 5a-3 displayed good selectivity for the ASGP receptor and showed obvious fluorescence signal in the HepG2 cell,other than the A549 cells.