Construction Of Metal Ions Sensor Based On Fluorescence Response And Research On Its Application

The human activity of the ore mining,smelting and industrial waste water emissions have led to a large number of heavy metal ions into the environment.Heavy metal ions are different from other pollutants and can not be degraded by microorganisms.They can be migrated and accumulated through food chain and eventually be ingested by human body,thus causing a series of health problems.Therefore,the effective monitoring of heavy metal ions in the environment is very important,and it is also an important prerequisite for environmental treatment.Fluorescence detection technology is an effective detection technology with the advantages of good selectivity,high sensitivity,low detection cost,fast response time,and visible response signal.They has been successfully applied to various fields such as environmental detection and biomedicine and so on,especially in the application of heavy metal ions detection.In recent years,the fluorescent probes reported at home and abroad have also achieved good results for the detection of specific target metal ions.But at the same time,most of the defects of most probes have also been greatly limited in the application and popularization,such as tedious preparation process,low sensitivity and single response,which has become an urgent problem for scientific researchers.In this paper,a series of floredcent probes with simple preparation procedure and good detection results are constructed,including single and reversible fluorescent probe,relay identification fluorescent probe,double responsive fluorescent probe and multiple response fluorescent probes.And realized selective detection of specific targets metal ions in the environment and in the organism.A series of characterization,detection and mechanism experiments of the optical properties of those probes system were carried out,and the physicochemical properties,optical signal change mechanism and selective response of those probes to target ions were elucidated.1?Construction of a reversible Cu²⁺fluorescent probe and research on its applicationA novel ON-OFF fluorescence probe was constructed based on the principle of increasing the conjugation degree of cinnamaldehyde system by the introduction of a simple simple C=N double bond.The probe showed unique optical response selectivity for Cu²⁺.When the Cu²⁺ions were added to the probe solution system under UV irradiation,the green fluorescence of the system was quenched,and the fluorescence signal was visible to the naked eye.And the optical properties and recognition properties of the probe were discussed and analyzed by a series of optical spectra.It is found that the probe had the advantages of a low detection limit(2.65×10^-9 M),strong anti-interference and reversibility for Cu²⁺ions.Meanwhile,the geometric configuration and energy level distribution of the probe and the[probe-Cu²⁺]complex were calculated and analyzed based on the density functional theory to further assisting in understanding response mechanism.Finally,the low toxicity and good cell penetrating probe was also applied to the imaging analysis of target ions(Cu²⁺)in living cells,which showed the practical application value of the probe in living cells.2?Construction of a relay identification fluorescent probe for Fe³⁺and phosphate ions and research on its applicationA novel type relay identification fluorescent probe for Fe³⁺and PO₄^3-ions was designed and constructed by using the rigid planar structure of cyanophenyl as the fluorescent signal group and introducing the phenyl thiazole with strong affinity nitrogen atoms to improve its selective recognition.The probe showed excellent selective fluorescence quenching response for Fe³⁺,and the[Probe-Fe³⁺]complex system can also be used as a new in situ detection system for relay identification of PO₄^3-and released free probe molecule to restore red fluorescence.Based on a large number of optical experiments,it is found that the probe and the[Probe-Fe³⁺]complex have high selectivity,sensitivity and anti-interference for Fe³⁺and PO₄^3-,respectively.The formation of the[Probe-Fe³⁺]complex was also verified by mass spectrometry and UV visible absorption spectra.The stoichiometric ratio and combination mode of the probe and Fe³⁺were discussed based on the Job'plot and DFT calculation.Similarly,the probe was successfully used in the the spiked test experiment of Fe³⁺in the real water samples and the imaging of the target ion in the living cells.The probe provided a platform for the development of new type fluorescent probes for the relay identification of metal cations and anions.3?Construction of a double recognition fluorescence probe for Zn²⁺and Hg²⁺and research on its applicationFirst,2,6-dimethylacyl-4-methylphenol with symmetrical structure was designed and synthesized,then the novel double recognition fluorescence probe was constructed based on the introduction of target ion response site to two formyl groups.The probe exhibited green and red fluorescence response signal and high selectivity and sensitivity to Zn²⁺and Hg²⁺ions in pure water,respectively.Based on a series of spectroscopic experiments,it is found that the detection limit of the probe for Zn²⁺and Hg²⁺ions can reach nanomolar level,and the binding constant is high and the anti-interference ability is strong.Meanwhile,the geometric configurations of the probe and complex,the frontier molecular orbitals and NBO were analyzed based on DFT,and expounded the fluorescence response mechanism of probe to Zn²⁺and Hg²⁺ions.At the same time,the probe was successfully used in the the spiked test experiment of Zn²⁺and Hg²⁺in the real water samples and the imaging of the target ion in the living cells.This work proposed a fluorescence detection method for single probe recognition of bimetallic ions,which improved the detection efficiency of metal ions in the environment and the organism,reduced the cost of manpower and detection,and provided a new idea for the development of multi response fluorescence detection technology.4?Construction of a novel multiple responsive metal ions fluorescence probe for and research on its applicationA novel fluorescent probe with multiple recognition performance for Zn²⁺,Al³⁺,Fe³⁺and Cr³⁺was constructed based on the principle of metal ions controlling the spiral ring open ring of the Rhodamine dye and the isomerization of cyanophenyls to realize the fluorescence control.The probe itself has no fluorescence emission,and when it was combined with the target metal ion,the target ions induced different changes in the structure of probe and showing different fluorescence signals,respectively.The selectivity of the probe and the sensitivity to the target ion were discussed by the optical spectra.The influence of common metal ions and anions on the detection of target ions is also discussed.Based on the DFT theory,the geometric configuration of the probe and metal complexes were optimized,and analyzed the thermodynamic parameters and the frontier molecular orbital.At the same time,the experimental phenomenon and response mechanism were explained with ¹H NMR spectrum analysis.Finally,the probe was successfully used in the spiked detection of target ions in the real water samples.And a convenient test strip was prepared based on the probe,which can be used for fast qualitative analysis of target ions.This study layed the foundation for the simple and rapid detection of multiple metal ions in practical samples for the successful application of fluorescence detection technology.5?Construction of a dual site controlled probe for fluorescent monitoring of pH and colorimetric monitoring of Cu²⁺and research on its applicationA dual site controlled fluorescence probe was constructed based on acid controlled the spiral ring open ring of the Rhodamine B and alkali controlled the isomerization from enol to ketone structure of 3-formyl-4-hydroxy-4-cyanobiphenyl.The probe can be used to detect the fluorescence of the system pH and the colorimetric identification of Cu²⁺under the neutral condition.Under the acid condition,the probe system showed obvious red fluorescence emission,and the system showed a yellow-green fluorescence emission under the alkaline condition.The probe solution is colorless and non fluorescence under the neutral condition,but the addition of Cu²⁺caused the color change of the probe system from colorless to pink.The optical properties of the probe vary with the pH of the system environment.It is verified that the fluorescence properties of probe can vary with the change of pH in the environment,and it has good reversibility.In addition,the probe has the advantages of selectivity,high sensitivity and anti-interference for Cu²⁺colorimetric recognition.Except for Cu²⁺ions,there is no effect of common ions on pH detection.Finally,the response of the probe to the pH in the biologic cell was also discussed by the cell imaging experiment.