Preparation And Properties Of Fluorescent Probes Based On Rhodamine Derivatives

In recent years,the field of fluorescent probes has developed rapidly.It is an indispensable analytical method for scientific research to design suitable fluorescent probes to detect the target substance or target environment.Compared with traditional detection methods,fluorescence analysis has become a better choice for the detection of analytes due to its high selectivity,high sensitivity and easy operation.Based on the harm of heavy metal ions pollution,especially mercury ions pollution to human health,a series of mercury ion fluorescent probes have been successfully prepared to identify mercury ions in complex systems Ion probes still can not meet the needs of detection,so it is necessary to further improve the selectivity,sensitivity and adaptability to complex environment of fluorescent probes.With the increasing complexity of detection requirements,it is crucial to design suitable mercury ion probe according to the specific identification environment.Based on the luminescent principle of fluorescent substances,the recognition mechanism of fluorescent probes and the related exploration of scientific researchers,five fluorescent probes based on oxaanthracene structure were designed for mercury ion:FLHC,R6GHC,RhoBdoHC,Rho BHC and Rho16HC.For each of the five fluorescent probes synthesized,the structures were characterized and analyzed by ¹H NMR,¹³C NMR and HRMS to confirm the unambiguously synthesized product structures.The maximum fluorescence emission wavelengths of the five fluorescent probes are 530 n M,555 n M,558 n M,595 n M and 640 n M respectively.Different fluorescence emission wavelengths can accommodate different detection requirements.This series of probes are spiro hydrazide derivatives,which have special conjugated structure and strong fluorescence performance.The electron distribution and space of the recognition site are very suitable for interaction with mercury ions.Through a series of tests on the optical properties of the probes before and after the recognition of mercury ions,it can be found that the ring opening of fluorescein spiro ring can occur quickly after the addition of mercury ions,and the fluorescence can be detected in sunlight and in the air Under the irradiation of UV lamp,the color changes can be seen by naked eyes,and its UV-Vis absorption spectrum has a strong absorption peak,and its fluorescence spectrum also has a significant emission peak.In this paper,the selectivity,anti-interference ability,detection limit,complexation constant,p H interference,binding mechanism and visualization application of the probes were also studied,which can prove that the four probes are effective in identifying mercury ions Excellent performance in ability.These probes can interact with Hg²⁺at the ratio of 1:1,and the conjugated system can be recovered by opening the spiro ring of spiro hydrazide,thus realizing the change of fluorescence from"off"to"on".The selective experiment and anti-interference experiment can prove that the specific recognition ability of the five probes to Hg²⁺is also excellent,which can realize the selective recognition of Hg²⁺in complex environment.The detection limits of the five probes are 10.4 nm,12.5 nm,16.2 nm,8.01nm and 15.4 nm,respectively.The results are satisfactory.The responses of the five probes to mercury ions can be identified by naked eyes.Based on the configuration of solution,there are still some tedious steps to simplify the operation.Immerse the filter paper in the solution of fluorescent probe,fully immerse and dry in air to obtain mercury ion test paper.The experimental results show that the test paper is colorless in sunlight and blue in ultraviolet light when it is not exposed to mercury ion solution;when it is exposed to mercury ion solution,the test paper can have significant color change both in sunlight and ultraviolet light.Thus,it can realize more convenient detection of mercury ion.Based on the longer fluorescence emission wavelength after the recognition of mercury ions by fluorescent probe Rho16HC,and its fluorescence energy is lower and less susceptible to background interference,the application of fluorescent probe Rho16HC in RAW 264.7 cells was further investigated.RAW 264.7 cells with absorbed fluorescent probe Rho16HC showed strong red fluorescence after being incubated with mercury ion solution,thereby it could be illustrated that the fluorescent probe Rho16HC could be successfully applied to the detection of exogenous mercury ions in living cells,which indicated that the probe also had a certain potential on bioapplications.