Synthesis And Properties Of Rhodamine-based Fluorescent Probesfor Heavy Metal Ions And PH

People's health awareness has been stronger and stronger with the rapid development of society.It is well known that some heavy ions are essential trace elements in living organisms.Although these elements are rare,they are closely related to human health and cell metabolism.Therefore,it is very important to detect these heavy metal ions rapidly.Compare with many analytical methods,the fluorescence method has attracted the attention of many researchers due to its advantages,high selectivity,high sensitivity,easy operability and wide application range.Because rhodamine dyes have good stability,high molar extinction coefficient and the large Stokes shift,the fluorescent probes for Cu²⁺,Fe³⁺and H⁺have been synthesized in this thesis.Chapter 1:Fluorescence generation mechanism,recognition mechanism,and progress of fluorescent probes were mainly summarized.The significance and innovation of this paper was put forward.Chapter 2:A novel rhodamine-based fluorescent probe?RN?was designed and synthesized,which can generate a large fluorescent signal upon the addition of Fe³⁺ions.The structure of RN was confirmed by ¹H NMR?¹³C NMR and HRMS.The results show that the fluorescence intensity of the RN enhanced significantly when the concentration of Fe³⁺irons increased.The color of the system quickly turned to deep pink.The complex ratio between the RN and the iron was determined to be 1:1 by the experiment of the Job'Plot.The concentration of Fe³⁺has a good linear relationship with fluorescence intensity of the RN-Fe³⁺complex in the range of 1-20?mol/L?R²=0.9972?.In summary,a new analytical method of rapid detection of Fe³⁺was established.Chapter 3:The fluorescent probe?RL?was designed and synthesized by the rhodamineB hydrazide and N-aceticacid-3-indole aldehyde.The water solubility of the RL was increased owing to the addition of carboxyl group.The fluorescent probe is high selective and sensitive?6.02×10^-88 mol/L?,and the linear relationship is better within a range?2-10?mol/L?,in the aqueous solution?V?water?:V?acetonitrile?=8:2?.Chapter4:A novel fluorescent sensor molecule?RH?was designed and synthesized.The structure of RH was confirmed by¹H NMR ¹³C NMR and HRMS.The fluorescent probe did not response to common metal ions,but the fluorescence intensity of RH changes significantly upon binding to protons and the color of the solution rapidly changes to deep pink in a 50%ethanol/water solution.The results indicated that the fluorescence probe has high selectivity to H⁺and hardly interfered by other metal ions.The fluorescence intensity of the probe enhanced gradually the concentration of proton increasing.The dissociation constant of the probe was calculated pK_a=4.23.A new analytical method for rapid detection of the pH was established.