Synthesis Of Sodium Ion Fluorescent Probe Based On Crown Ether And Its Application In Microfluidic Devices

Sodium ion is the main cation in human extracellular fluid.It plays a crucial influence on the body's blood volume,cell osmotic pressure and acid-base balance,and involved in the generation and transmission of electrical excitement in nerve and muscle.The sodium ion absorption source of human body is mainly from food,so the determination of sodium ion content in food is of great significance to human health.This research designed and synthesized a new type of fluorescent probe for the test of sodium ions based on the recognition ability of 1-aza-15-crown ether-5,which provided a new method for the subsequent detection of sodium ions.Crown ether has a strong binding force to metal ions and some other small molecules,therefore crown ether is widely used in the design of fluorescent sensor systems,among which aza crown ether is more widely used.The nitrogen atom not only provides branch points for the introduction of other groups,but also is an effective donor electron group and metal binding site,so that its coordination and selectivity have been greatly improved.As a result,aza crown ether is widely used as various receptors in supramolecular chemistry.The main content of this thesis has been summarized as follows:1.The intermediate M-1 were efficiently prepared by reaction of 1-aza-15-crown-5 and 6-bromo-2-naphthaldehyde which based on the palladium-catalyzed amination and nucleophilic substitution.Then,the M-1 and 1,2,3,3-tetramethyl-3H-indolium iodide were refluxed in ethanol to finally obtained the pure compound named Probe2 with a yield of 53.2%.The structure of Probe2 was characterized by ¹H NMR,¹³C NMR,and MS.The spectrum performance of this probe was investigated and also the complex ratio,selectivity,and anti-interference properties in the presence of sodium ion.The results indicated that Probe2 is more sensitive to the polarity of organic solvents.Its UV-vis absorption peak and fluorescence emission peak were shown as blue shift and red shift respectively when the polarity of the solvent increases.The compound had the strongest absorbance value at pH 6,and its fluorescence intensity gradually increased with the increase of pH,and the position of the fluorescence emission peak gradually moved from 491 nm to 428 nm.The probe had good selectivity and anti-interference to sodium ion,the complex ratio was 1:1,and the binding constant was 2.55×10³ M^-1.2.The fluorescence intensity of Probe2 continuously enhanced with the addition of sodium ion,which showed an excellent linear relationship in the range of 1-10?mol/L,and the equation was y=1.15×10⁵x+1.94×10⁶,R²=0.998.The detection limit was 53.7 nmol/L.Taking the test results of ICP-MS as a reference while using Probe 2 to detect actual samples,it was found that the detection results of the two methods had outstanding correlation,r=0.9994,which proved the reliability of this method.3.In order to expand the application scope of the Probe2,it was applied to a self-made microfluidic paper-based analysis device and made into a portable product to achieve immediately and rapidly detect of sodium ion.The performance of this microfluidic device was investigated,which showed that the hydrophilic region and the hydrophobic region of the paper-based sensor were clearly separated,and no diffusion or leakage occurred during the dye droplet static experiment and wicking process.When the sodium ion concentration was in the range of 2-10 mmol/L,the relationship between the change distance?d,mm?of the fluorescence band and the sodium ion concentration?c?can be expressed as d=3.13c-0.14,R²=0.98.