Study On Synthesis And Properties Of Water-soluble Rhodamine-based Fe³⁺ Fluorescent Probe

In recent years,many fluorescent dyes have been used as fluorescent probe because of their high sensitivity and good selectivity.According to their characteristics,they can be used to detect metal ions,small molecules and even macromolecules in organisms.These detection methods are applicable as analytical tools in biochemical,environmental and medical areas.Rhodamine dyes are often used as fluorescent probe because of their unique photophysical properties,high extinction coefficient and quantum yield,great light stability and long fluorescence emission wavelength.Rhodamine spirolactam derivatives are nonfluorescent,whereas ring-opening of the corresponding spirolactam gives rise to strong fluorescence emission and a pink color.In a similar way,different groups are reacted on the carboxyl group of the rhodamine,an appropriate ligand on a spirolactam ring can induce a color change as well as a fluorescence change upon addition of metal ions.With the development of science,more and more fluorescent probes are used in biological systems.But this process is somewhat dependent on the water-soluble system.In recent years,there have been few reports on the water-soluble probes of rhodamines,and there are almost no rhodamine probes in pure water.Therefore,it has great significance to synthesize water-soluble rhodamine fluorescent probes.In this paper 5(6)-carboxylated rhodamine was synthesized and isolated successfully,a series of fluorescent probes were synthesized,which can identify ferric ions and study their properties.Firstly,we synthesized the 5(6)-carboxyrhodamine ethylenediamine salicylaldehyde successfully.Under the test condition of pure water,the performance of probes were investigated by ultraviolet and fluorescence spectra.The results show that 5-carboxylated rhodamine have gteat selectivity and anti-interference ability to ferric ions.The fluorescent intensity of 6-carboxylated rhodamine showed linear relationship with pH values between 8 and 12,which can be used to indicated the pH values.Secondly we synthesized the 5(6)-carboxyrhodamine diglycolamine successfully.The results of investigation by ultraviolet and fluorescence spectra show that 5-carboxylated rhodamine have great selectivity and anti-interference ability to ferric ions investigated by ultraviolet and fluorescence spectra,under the test condition of pure water.6-carboxylated rhodamine diglycolamine have no selectivity,it is not a probe.Thirdly we designed and synthesized the 5(6)-carboxyrhodamine isopropanolamine which has good solubility in pure water.Experiments have shown that they all have great selectivity and anti-interference ability to ferric ions.They have excellent wide pH stable region,and can be used to indicated ferric ions in live cells.