Study On Construction Of Salamo And Salamo-Salen-Salamo Type Polynuclear Metal(Ⅱ) Complexes And Fluorescent Chemosensors

Salen-type ligands,usually prepared by the Schiff base condensation reaction between diamine and salicylaldehyde derivatives under heating conditions,they were a typical class of Schiff base compounds that have been studied by scholars due to their N₂O₂cavity and excellent metal chelating ability with an unique N₂O₂cavity.A new class of oxime Salamo-type ligands has been formed by introducing oxygen atoms into the structure of Salen ligands due to the good electronegativity of oxygen atoms.This type ligands were more stable and less prone to hydrolysis than the traditional Salen-type ligands,and have better flexibilities.In recent years,grafting two or more classical ligand structures into one ligand to form hybrid ligands have been favored by researchers and made better progress.In this thesis,a series of homonuclear complexes were first constructed using Salamo-type ligands with aldehyde groups and a novel highly flexible polydentate Salamo-Salen-Salamo-type hybrid ligand H₄L²,and the induced regulation of complex configuration and nuclear number by anions was studied.In addition,the sensing properties of Zn²⁺/Mg²⁺（sensor ZT and MT）complexes generated in situ by H₄L²and Salamo-Salen-Salamo-type like compounds（sensor FT）were explored.1.Some research progresses on the grafting of Salen-type compounds with other functional groups to form hybrid ligands were presented,mainly focusing on the directional regulation of conformation and nuclearity for complexes by anions,and proposing the idea of directional construction of structurally novel and nucleationally different complexes.The development and main response mechanisms of fluorescent chemical sensors were briefly introduced.2.A N₂O₃-donor aldehyde-appended salamo-like ligand H₂L¹has been designed and successfully synthesized,and can be used to prepare complexes with different nuclearity and extraordinary structures by changing the reaction conditions（various counter-anions）.The experimental results show that under the same conditions,when using ligand H₂L¹to prepare complexes,which indeed have a certain dependence on counteranions and successfully obtained complexes 1-3:[{Cu（L¹）}₂]（1）,[Cu₃（L¹）₂（Et OH）₂]·2Cl O₄（2）and[Cu₃（L¹）₂（Me OH）₂]·2Cl O₄（3）.The crystal structure of complexes 1-3 were determined by single crystal X-ray diffraction experiment,the results showed that complex 1 was a novel（L¹）^2-:Cu²⁺=1:1 homobinuclear dimeric Cu²⁺complex.However,it was worth noting that the crystal structure of complex 2 is quite different from that of complex 1,the influence of the interaction of multiple counter-anions and solvents led to the formation of a novel（L¹）^2-:Cu²⁺=2:3 homotrinuclear centrosymmetric sandwich-like dimeric structure in complex 2.The structure of complex 3 is basically the same as that of complex 2,except that the ligand solvent is changed from ethanol to methanol.Finally,homonuclear dimers Cu²⁺complexes were characterized by elemental analysis and infrared spectroscopy.The coordination cavity,fluorescence properties,meantime electronic properties,weak interactions and free regions of free ligand and 1-3 were investigated.3.A flexible polydentate Salamo-Salen-Salamo hybrid ligand,H₄L²,with abundant cavities（Salamo and Salen pockets）was designed and synthesized,so that it may form unique coordination modes with transition metal ions.four novel complexes were obtained in the experiment,and the crystal structures of the complexes were determined by X-ray diffraction:novelbutterfly-shapedhomotetranuclear[Ni₄（L²）（μ₁-OAc）₂(μ_1,3-OAc)₂（H₂O）_0.5（CH₃CH₂OH）_3.5OH)_3.5]·4CH₃CH₂OH（4）,helical homotriplex[Zn₃（L²）（μ₁-OAc）₂]·2CH₃CH₂OH（5）,double-helical homoduplex[Cu₂（H₂L²）₂]·2CH₃CN（6）,mononuclear[Ni（H₂L²）]·1.5CH₃COCH₃（7）.The effects of different anions(OAc^-and（O₂C₅H₇）^2-)on the coordination behavior of H₄L²with transition metals were studies.The fluorescence properties of the four complexes were studied with zebrafish,it was observed that complex 5 was a potential luminescent material.Finally,in order to further investigate the weak interactions and electronic properties of free ligands and four complexes,simulation analyses such as interaction region indicators,Hirshfeld surface analysis,theoretical calculations,and electrostatic potential were conducted.4.Based on the above compound H₄L²,which in-situ formed Zn（II）complex（sensor ZT）and Mg（II）complex（sensor MT）were successfully obtained for highly selective and sensitive detection of H₂PO₄^-in DMSO/H₂O（9:1,v/v）solution.,ZT exhibited a blue-green fluorescence signal,when H₂PO₄^-was added,the fluorescence signal quickly disappeared under a 365 nm UV lamp,MT emitting bright blue fluorescence also exhibited specific fluorescence quenching of H₂PO₄^-under the same conditions.The binding mechanism and mechanism were studied through spectral analysis,Job’s plots,high-resolution mass spectrometry,and ¹H NMR analysis.Finally,a solid-state fluorescence test strip experiment was conducted to investigate the practicality of the sensors.The biological applicability of ZT and MT to H₂PO₄^-were evaluated through biological imaging experiments of zebrafish and bean sprouts.5.A Salamo-Salen-Salamo like long-chain compound（the sensor FT）was successfully designed and obtained,it was used for the highly specific detection of Fe³⁺and Cu²⁺in ACN/H₂O（9:1,v/v,p H=7.2）solution.When Fe³⁺and Cu²⁺were added to the sensor FT under 365 nm UV lamp,respectively,resulting in fluorescence quenching of the FT that exhibited blue fluorescence.In addition,the unique colorimetric sensing behavior of FT on Cu²⁺was studied,a strong absorption band was observed at 500 nm and the solution color changed from colorless to red after adding Cu²⁺.Based on the Job’s plot,high-resolution mass spectrometry,and theoretical calculations,the binding ratio and sensing mechanism of FT to target metal ions were proposed..Finally,the paper strip and zebrafish bioimaging experiments were successfully carried out,which provided a basis for further detection of Fe³⁺and Cu²⁺in the environment.