Synthesis And Properties Of Fluorescent Probes Using Rhodamine As Fluorophore

Metal ions widely exist in our lives and play a very important role,not only in chemical reactions,but also in the human body.The imbalance of metal ions in the body can cause very serious consequences.Therefore,it is particularly urgent to find a suitable method to detect metal ions in the body.Compared with the traditional method,the fluorescence detection method emerging in recent years has good selectivity,high sensitivity,real-time detection,easy portability and low price.It has attracted extensive attention of researchers and has been applied to many fields,such as:chemical field,environmental monitoring and biomedicine,etc.The fluorescent probe expresses an easily identifiable fluorescent signal through the binding or chemical reaction between the main body and the substance to be identified,so that people can clearly see the state of the substance to be detected,and then perform quantitative monitoring in real time.Based on the above reasons,in this paper,three new fluorescent probes were designed and synthesized using rhodamine as the fluorophore,which achieved the purpose of strong visualization,high sensitivity,and high selectivity in identifying Fe³⁺and Al³⁺among many metal ions.（1）A novel rhodamine fluorescent probe PZ1 was synthesized using rhodamine B,2-Hydroxy-5-methylisophthalaldehyde,and 2-hydrazinopyridine as raw materials,which showed excellent performance in acetonitrile After combining with Fe³⁺and Al³⁺,the two metal ions combine with the recognition group of the probe to induce rhodamine ring opening,restore its large conjugated structure,and emit a color change visible to the naked eye.Its structure was characterized by ~1H NMR,¹³C NMR,ESI-HR-MS spectroscopy.The probe has good selectivity to Fe³⁺and Al³⁺measured by UV-vis and fluorescence spectrophotometer,and shows good anti-interference ability in other metal ions,and the probe can quantitatively detect metal ions well,According to the Job curve,the binding ratio of probe to Al³⁺is 1:2.（2）PZ2 was synthesized from rhodamine B,2-Hydroxy-5-methylisophthalaldehyde,and hydrazino-benzothiazole.The probe was tested in acetonitrile.When the probe was combined with Al³⁺,it showed a color change visible to the naked eye,and the solution changed from light yellow to pink,realizing naked eye observation.During the test,it was found that when the probe was combined with Fe³⁺,it also showed fluorescence increased at 580 nm,while the fluorescence hardly changed after other metal ions were combined with the probe.In addition,the test results of the probe by UV-vis and fluorescence spectrophotometer show that the metal ion has a good linear relationship with the probe,indicating that the probe can quantitatively detect metal ions,and the probe has a low detection limit,which is suitable for Fe³⁺and Al³⁺.The limits of detection（LOD）for both Al³⁺and Fe³⁺were 0.13μM and 0.12μM,respectively.Moreover,the probe has good selectivity and anti-interference ability,According to the Job curve,it is inferred that the binding ratio of the probe to Fe³⁺and Al³⁺is 1:2.（3）A novel ratiometric fluorescent probe PZ3 was constructed by using piperazine-rhodamine as the parent and modifying it to obtain rhodamine derivatives.Its structure was characterized by ~1H NMR,its recognition mechanism was analyzed,and its properties were explored by UV-vis and fluorescence spectrophotometry.