The Novel Copper (?) Fluorescent Probes Based On The Rhodamine 6G And Rhodamine B

With the rapid development of supramolecular chemistry,molecular recognition has become a research hotspot in the field of biology,chemistry and material science.According to the varieties of signals,such as optical,magnetic,electrical,etc,caused by the interaction between the subject and the object,can be used for qualitative or quantitative detection of the object,also can be a powerful tool to study the mechanism of the interaction.Among of them,the detection method based on optical signals,like ultraviolet and fluorescence spectrum,has the important applications in the test of metal ions,biological molecules due to the superiority of simple and sensitive.As the trace elements in organisms,copper has a vital role in the metabolism of the organism.On the other hand,as an environmental pollutant,the copper ion has an adverse effect on water and soil.Therefore,to recognize the copper ion simply,rapidly and sensitively has a potential value and important significance.In this paper,four novel copper???fluorescent probes,probe 1,2,3 and 4,were synthesized by introducing the 2-hydrazinylethanol and 2-hydrazinylpyridine groups into rhodamine 6G and rhodamine B respectively and exhibited fluorescent signal enhancement induced by copper ion.In spectrum experiments,all of them showed the high selectivity for copper ion in acetonitrile/water solvent and accompanied the obvious color change.The “turn-on” constants and detection limits were measured by fluorescent titration experiment.The detection limits of four probes were lowered to 10^-8 M-10^-10 M,respectively,which suggested all of them had the high sensitivity for copper ion.The recognition mechanism of four probes was based on Cu²⁺-promoted hydrolysis reaction which was confirmed by HRMS.In the competition experiments,four probes showed good resistance capability to other ions.The fluorescent experiment in different pH indicated the range of neutral,weak acid and base was the optimum condition for recognition events.The probe 1 and probe 3 can be applied to detection of Cu2+ in living cells.The excellent properties mentioned above established a foundation for using four probes in real samples.