Design,Preparation And Properties Of Fe³⁺ And Mg²⁺ Fluorescent Probes

Recent years,fluorescent probes have been widely used in the fields of chemistry,biology,medicine,environmental science and other fields due to their high sensitivity,good selectivity,low detection limit and real-time monitoring.With the economic development of society and the improvement of human living standards,the content of various metal cations in environmental life systems is gradually increasing.Therefore,timely and effective detection of these ions is of great significance to environmental safety and life safety.In the present work,three kinds of fluorescent probes were designed and prepared by organic synthetic chemistry,and their properties were studied to detect and identify Fe³⁺and Mg²⁺in detail.The main works are as follows:（1）A simple shutdown fluorescent probe L based on a ruthenium structure for Fe³⁺was designed.In common metal ions including Cu²⁺,Zn²⁺,Fe²⁺,etc.,the probe exhibits high selectivity recognition for Fe³⁺in DMSO-HEPES buffer solution（20m M,pH=7.0,1:1（v/v））.After the addition of excess Fe³⁺,the molecular structure of the probe was converted from dimethyl acetal to furfural,resulting in fluorescence quenching and a yellowish brown color.（2）A Mg²⁺selective fluorescent probe Q1 was designed.The probe Q1 was prepared by reacting with benzoyl hydrazide on the basis of 8-hydroxyquinolin-5-aldehyde molecule,and its structure was characterized and fluoresce ntly tested.It was found that Q1 can not only be used selective recognition of Mg²⁺and Ca²⁺by fluorescence enhancement at 545 nm and selective recognition of Cd²⁺and Zn²⁺by fluorescence enhancement at 557 nm in methanol solvent.The titration experiment further determined that the ratio of the probe to the ion was 2:1,and it was determined that the nitrogen atom and the hydroxyl oxygen atom in the quinoline of the probe molecule participated in the coordination.The theoretical calculation results fur ther indicate that Q1 and Mg²⁺are coordinated.After the energy gap is reduced,the electron cloud is also close to the center of Mg²⁺,and the electron cloud density is increased,thereby exhibiting fluorescence enhancement in the fluorescence spectrum.（3）On the basis of the 8-hydroxyquinoline-7-aldehyde molecule,a Mg²⁺fluorescent probe Q2 was obtained by reacting an amine unit with a coumarin structure,and its properties were tested.In the aprotic solvent acetonitrile,Q2 can selectively recognize Mg²⁺by fluorescence enhancement at 520 nm,and can also enhance fluorescence to selectively identify Zn²⁺at 520 nm in the protic solvent ethanol-water（9:1,v/v）.Through the titration experiment,the ratios of probe Q2 to Mg²⁺and Zn²⁺were determined to be 1:2 and 1:1 respectively.The recognition mechanism of probe Q2 molecules for Mg²⁺and Zn²⁺in different solvents was analyzed according to DFT calculation.