Design And Preparation Of Novel Metal Ion Fluorescent Probes And Its Application In Environmental Water Samples And Organisms

Metal ions play an indispensable role in the physiological system of living organisms.With the increasingly serious problem of metal ion pollution,once the metal ions in the human body are unbalanced under the action of the food chain,human health will be greatly affected,leading to physiological dysfunction,and may even inducing life-threatening disease.Due to the excellent detection performance of fluorescent probes in the detection and analysis of metal ions,the development and application of fluorescent probes has become a research focus of the research community.In this paper,we have prepared a series of novel relay-recognition fluorescent probes for detection and identification of various ions and solves the limitation of single recognition response of fluorescent probes.?1?A coumarin-based,water-soluble,relay-recognition fluorescent probe was designed and synthesized by using 2-pyridylmethylamine containing a strong affinity nitrogen atom as a selective recognition group.The fluorescent response of probe L1to a series of common metal ions was investigated and it was found that only Fe³⁺quenched the blue fluorescence.Further investigation of the fluorescence detection performance of probe L1 for Fe³⁺by the fluorescence emission spectrum shows that it has the advantages of single selectivity,high anti-interference,reversibility,detection limit as low as 3.2×10^-77 M for Fe³⁺detection.In addition,the subsequent study found that L1-Fe³⁺complex can be highly selective in the original test environment to identify PO₄^3-accompanied with strong blue fluorescence signal recovery.Based on the combination of the experimental test's Job's curve and theoretical calculations,the binding ratio and combination of the probe L1 and Fe³⁺were discussed.The fluorescent probe L1 has excellent water solubility,and its low cytotoxicity can realize relay identification of Fe³⁺and PO₄^3-in biological cells.This work provides new ideas for the design and development of new fluorescent probes for chemical analysis and detection of cations and anions in the biological field.?2?A novel coumarin-based small-molecule probe L2 was designed and synthesized based on the principle of C=N isomerization by grafting of benzoyl hydrazide on coumarin dyes with a simple C=N double bond.The fluorescent probe L2 can be applied for relay recognition of Al³⁺and F^-ions.The probe exhibited a significant fluorescence enhancement response to Al³⁺in a mixed solvent of DMSO:water?1:99,v/v?.The fluorescence experimental results show thatprobe L2 has single-selectivity,high sensitivity,fast response,low detection limit?0.014?M?,and a binding constant of 5.453×10⁴ M^-11 for Al³⁺.In addition,the generated L2-Al³⁺complexes have excellent selective detection performance for F^-with the fluorescence signal quenched under the same test conditions.The probe L2 was successfully applied to the relay recognition for Al³⁺and F^-in biological cell samples,demonstrating the applicability of this probe for ion detection in living organisms.?3?Based on the principle of increasing the conjugate degree of8-hydroxyquinoline system to enhance its fluorescence,a novel blue fluorescent probe L3 was designed and used for relay recognition of Cu²⁺and Cd²⁺ions.A series of analytical tests,such as ultraviolet absorption spectrum and fluorescence emission spectrum,were conducted to investigate the detection performance of this probe to Cu²⁺and Cd²⁺ion.The experimental results showed that the probe L3 exhibited strong fluorescence quenching,high selectivity,anti-interference ability,sensitivity,and a wide range of pH values applicable in the detection of Cu²⁺.The probe L3-Cu²⁺complex is further used as a selective detection probe for Cd²⁺ions,which shows a clear yellow-green color and avoids the poor detection sensitivity and large errors caused by the small red shift of the spectrum fluorescence emission spectrum when the probe L3 is directly used for Cd²⁺detection.Based on the excellent experimental detection performance described above,the probe is highly efficient and suitable for the detection and recognition of the Cu²⁺and Cd²⁺ions in the actual water sample and the paper-based test strip based on the probe can also be conveniently and quickly used for on-site sampling and detection.