Design, Synthesis, Detection And Application Of The Rhodamine 6G-based Fluorescent Probes For Metal Ions

Using fluorescent probes to detect metal ions in environment and organism have always been the hot spot of the chemical research,because of the advantages of high sensitivity,good selectivity and visibility.Fluorescent dye of Rhodamine 6g is broadly utilized in the detection of heavy metal ions and transition metal ions for their superior photophysical properties and photostability,and available mechanism of“on-off”.In this thesis,three kinds of new fluorescent probes based on Rhodamine 6g derivative were synthesized and investigated for their applications in the detection of metal ions.The details were as follows:1?The probes 4a-4f of chain double 1,2,3-triazole Rhodamine 6g were designed and synthesized by using the Click reaction.The colorimetry and fluorescence alteration determined that probe 4d was the best one to specifically recognize the Fe³⁺.The probe 4d bond Fe³⁺by 1:1stoichiometry with an association constant of 2.25×10⁵M^-11 and a detection limit of 7.7×10^-6M in CH₃CN/H₂O=1/1?V/V,10mMPBS,pH=6.5?solution.Besides,the recognition reaction was reversible.2?A novel fluorescent probe basing on Rhodamine 6g-Schiff was designed and synthesized,and recognized Fe³⁺in aqueous solution which according to fluorescence mechanism of“off-on”.It was studied that probe 4a was the best one to recognize Fe³⁺with great selectivity in CH₃CN/H₂O=1/1?V/V,10mMPBS,pH=6.5?solution.Meanwhile,the recognition reaction was reversible without interference of other coexisting metal ions.3?Since quinoline derivatives could be exploited as fluorescent probe,Rhodamine 6g-based probes containing hydrazide was also synthesized.Rhodamine 6g probe containing biquinoline acid ligand exhibited the best recognition effect for Cu²⁺,compared with probes containing other acid ligands,The result suggested that2,2'-biquinoline-4,4'-dicarboxylic acid ligand induce the opening of lactam-ring of Rhodamine 6g and the forming of coordination bond with Cu²⁺,and the forming of fluorescence sequentially.Certainly,the whole reaction was also reversible.