Fluorescence Sensor For Continuous Detection Of Metal Ions And Anions

Since mankind entered the industrial revolution,the pollution of heavy metal ions emitted by industry to the water and soil resources in the environment is a serious threat to human health and survival of other life on the plante.In addition,anions are also closely related to human production and life.Anions participate in and act on many important human activities.Therefore,it is particularly urgent to develop a simple and rapid method with a single selective identification of a specific ion.In recent years,fluorescent chemical sensors have broad application prospects in metal ions and anions in qualitative and quantitative detection environments due to their advantages of simple and convenient operation,good selectivity,high sensitivity and low cost.Fluorescence chemical sensors detect and identify anions in addition to the sensor directly and anion selective recognition,we can also use some good metal cation sensors to indirectly detect and identify anions using"displacement strategy".Since the anion can form a stable complex with the metal cations,and the association constant of some anions and cations is much larger than the association constant of the cation and the sensor,the anion can take metal ions from the composite formed by the sensor and the metal ions,so that the optical signal of the sensor is changed to achieve the purpose of detecting anions,and this type of anion sensor have high sensitivity and selectivity even in real samples and biological cells.This paper designed and synthesized a series of new fluorescent chemical sensors that could recognized metal ions and recognized the anions based on the recognition of metal ions.Their structures were confirmed by ¹H NMR,¹³C NMR,HRMS and IR spectroscopy.According to fluorescence spectroscopy,ultraviolet absorption spectroscopy,nuclear magnetic titration,mass spectrometry titration and density functional theory calculation,the sensor and some metal(Na⁺,Li⁺,K⁺,Zn²⁺,Ca²⁺,Mn²⁺,Ni²⁺,Ba²⁺,Pb²⁺,Hg²⁺,Fe²⁺,Cd²⁺,Al³⁺,Ag⁺,Cr³⁺,Mg²⁺,Cu²⁺,Fe³⁺and Co²⁺)ion selective recognition,complexation mode and sensing mechanism were explored.And continued to explore the sensor-metal complexes for some common anions(F^-,Cl^-,Br^-,I^-,SO₄^2-,SO₃^2-,SH^-,S^2-,NO₃^-,CO₃^2-,CH₃COO^-,HCO₃^-,HSO₃^-,SCN^-,HPO₄^2-)selection and the ability of the sensor to recognize in biological cells.The specific content of this paper is as follows:?1?A brief and concise introduction to the development of supramolecular chemistry and the principles and implications of molecular recognition and its associated fluorescent chemical sensors.The recent studies on the selective recognition of anion fluorescence by metal ions and metal ion-based sensors are summarized.The design concept of this thesis is put forward.?2?The fluorescence sensor L-1 was designed and synthesized.The fluorescence single-selective identification of common metal ions by sensor L-1 was investigated by fluorescence spectroscopy,ultraviolet spectroscopy,nuclear magnetic titration and HRMS mass spectrometry.Sensor L-1 has excellent fluorescence single responsed recognition for Zn²⁺in aqueous solution,and further selectively recognized tartaric acid anions based on its complex with Zn²⁺.According to common spectroscopy studies and ¹H NMR titration methods,the possible complexation modes and sensing mechanisms between sensor L-1 and Zn²⁺and tartaric acid anions were proposed.?3?The L-2 was designed and synthesized based on coumarin,the structure was characterized by ¹H NMR,¹³C NMR and high resolution mass spectrometry.A single selective response to common metal ions in DMF/HEPES buffer?1:1 v/v,10 mM,pH=7.2?solution was investigated by fluorescence spectroscopy and ultraviolet absorption spectroscopy.And based on its complexation with metal ions,the fluorescence selective identification of its complexes to common anions was further explored.Sensor L-2 has excellent fluorescence enhancement recognition for Ca²⁺in DMF/HEPES buffer solution,and its complex L-2-Ca²⁺can further selectively recognized F^-.The possible complexation modes and sensing mechanisms between sensor L-2 and Ca²⁺and F^-were proposed by HRMS mass spectrometry,¹H NMR titration and DFT.?4?Two chemical sensors L-3 and L-4 based on coumarin as fluorophores were synthesized.They were explored by fluorescence,ultraviolet absorption and infrared spectroscopy that the sensors L-3 and L-4 have good fluorescence selectivity to Zn²⁺in aqueous solution.And their complexes L-3-Zn²⁺and L-4-Zn²⁺with Zn²⁺could further selectively recognize HPO₄^2-.The sensing mechanism and complexation mode between L-3 and L-4 and Zn²⁺and HPO₄^2-were proposed by ¹H NMR titration,HRMS mass spectrometry and density functional theory calculation.