Synthesis,characterization And Detection Of Zn²⁺,Cu²⁺,Fe³⁺,Al³⁺,Cr³⁺ As Fluorescent Probes Of Benzochromone Schiff Base Ligands

The fluorescent probes are widely used in the detection of anions,cations and macromolecules due to their high selectivity,high sensitivity,low detection limit,and low detection dose.In this paper,the chromone derivative 7,8-benzochromone-3-aldehyde was synthesized by multi-step organic reaction using 1-naphthol as raw material,and three kinds of Schiff base fluorescent probes were designed and synthesized by using it.The structures of the probes were characterized by hydrogen spectroscopy,carbon spectroscopy,mass spectrometry,etc.,and their fluorescence properties were studied by fluorescence spectroscopy,ultraviolet-visible spectroscopy,and infrared spectroscopy.The specific content of the thesis mainly consists of three parts:The first part briefly describes the synthesis and characterization of7,8-benzochromone-3-aldehyde（fluorescein acyl）hydrazone（LI）as a fluorescent probe for Zn²⁺and a colorimetric probe for Cu²⁺.L_I exhibits an obvious fluorescence-enhanced specific selective response to Zn²⁺in Et OH/H₂O（9/1,V/V）solution,which is attributed to the coordination between probe LI and Zn²⁺,which hinders photoinduced induction Electron transfer process（PET）,and experimental investigation found that other metal ions did not interfere with this selectivity.In addition,when we added Cu²⁺to the Et OH/H₂O（5/2,V/V）solution of LI,the color of the solution could be observed to change from colorless to yellow immediately.LI can detect Cu²⁺with naked eyes,which is an advantage of probe LI.The second part introduces 7,8-benzochromone-3-aldehyde（rhodamine B acyl）hydrazone(L_II)as a fluorescence-enhanced probe to detect Zn²⁺and M³⁺(Fe³⁺,Al³⁺,Cr³⁺)at different excitation wavelengths,respectively..Based on the mechanism of rhodamine B’s ring-opening recognition of trivalent metal ions,LII exhibits high selectivity,high sensitivity and detection limit as low as 10^-8 M for M³⁺in Me OH solution.In addition,in Et OH/H₂O（15/1,V/V）solution,LII has higher selectivity for the detection of Zn²⁺than other metal ions.The third part introduces the use of 7,8-benzochromone-3-aldehyde（4-aminoantipyrinoyl）hydrazone（LⅢ）as a fluorescence-enhanced probe to realize the detection of Al³⁺.From the calculation of the titration curve,it can be concluded that the detection limit of LⅢfor Al³⁺is as low as 10^-7 M.In addition,the probe can also be used as a solid probe to achieve rapid detection of Al³⁺without the interference of other metal ions.