Design,Synthesis And Application Of Fluorescent Probes Based On The Xanthene

In recent years,fluorescent probe detection technology has developed rapidly in environmental analysis and biological analysis of ion detection due to simple operation,good selectivity,high sensitivity,rapid response and low cost,and has become one of the hot spots in analytical chemistry.Based on different fluorescent probe recognition mechanisms,several fluorescent probes were designed and synthesized with Rhodamine,fluorescein and other fluorescent dyes as raw materials in this paper,and were used to detect several kinds of ions in drinking water and bioactive cells such as Cr³⁺,Al³⁺,F^-,Cu²⁺,H⁺in this paper.The main contents of the study are as follows:?1?A trivalent chromium(Cr³⁺)fluorescence probe?RhC?was designed and synthesized via Schiff base reaction based on rhodamine-crown ether conjugate.This probe displayed a favorable selectivity for Cr³⁺over a range of other common metal ions in DMF/H₂O?3:7,v/v;PBS buffer 50 mmol/L;pH=6.8?solution,leading to prominent fluo-rescence“OFF–ON”switching of the rhodamine fluorophore.The limit of detection was calculated to be 1.5?mol/L?S/N=3?.The binding ratio of RhC-Cr³⁺complex was determined to be 1:2 according to the Job's plot and HR-MS.The probe was successfully applied to examination of Cr³⁺in drinking water spiked samples.The recoveries ranged from 104.9%to 106.9%at spiked concentration level of 10.00?mol/L,and the obtained results were con-sistent with those obtained using atomic absorption spectrometry?AAS?.Moreover,bioimaging experiments showed that RhC can sense the Cr³⁺in living cells with a fluorescence enhancement signal.?2?A novel water-soluble and reversible fluorescent probe?Flu-Py?based on fluorescein,was designed and synthesized for the sequentially“ON–OFF–ON”fluorescent detection of Al³⁺and F^-in concentration range of 0-10?mol/L and 0-30?mol/L,respectively,with high sensitivity and excellent selectivity.The detection limits for Al³⁺and F^-were 0.092?mol/L and 0.112?mol/L,respectively.The binding mode and sensing mechanism of Flu-Py with Al³⁺was verified by density functional theory?DFT?and time dependent density functional theory?TDDFT?calculation.The“ON-OFF–ON”fluorescent property of Flu-Py upon the addition of Al³⁺and F^-was utilized for the imaging of living cells.?3?A novel water-soluble and reversible fluorescent probe?RBA?was designed and synthesized based on a rhodamine B derivative.This probe displayed a favorable selectivity for Cu²⁺over a range of other common metal ions in CH₃CN/H₂O?3:7,v/v;HEPES buffer 50 mmol/L;pH=7.4?solution.The limit of detection was calculated to be 0.085?mol/L?S/N=3?.The binding ratio of RBA-Cu²⁺complex was determined to be 1:1 according to the Job's plot.The binding mode and sensing mechanism of RBA with Cu²⁺was verified by density functional theory?DFT?calculation.The probe was successfully applied to examination of Cu²⁺in drinking water spiked samples.The recoveries ranged from 100.8%to 101.1%at spiked concentration level of 10.00?mol/L,and the obtained results were con-sistent with those obtained using atomic absorption spectrometry?AAS?.Moreover,bioimaging experiments showed that RBA can sense the Cu²⁺in living cells with a fluorescence enhancement signal.?4?Fluorescein-rhodamine 6G?Flu-Rh?was synthesized and used as the fluorescence probe for pH measurement based on fluorescence resonance energy transfer?FRET?.This probe displayed a favorable selectivity for H⁺over a range of other common metal ions in CH₃CN/H₂O?1:1,v/v;Britton–Robinson buffer;pH=2.5-7.5?solution.The sensing mechanism of Flu-Rh with H⁺was verified by density functional theory?DFT?calculation.The probe was successfully applied to examination of H⁺in chemical plant sewage and urine of diabetic patients.