Study On Fluorescent Probes Of Salamo-type Polyoximes And Synthesis,Crystal Structure,and Properties Of Transition Metal (?) Complexes

Due to the susceptibility of salen-type compounds to hydrolysis as well as exchange reactions,a novel salen-type derivative salamo has been developed and the analogue has attractive properties and applications in supramolecular structures,catalysis,electrochemical conduction,luminescent and magnetic materials,and biology.In this thesis,two asymmetric salamo-type ligands,H₂L¹ and H₂L²,were designed and synthesized,and their four transition metal(?)complexes were grown up.The structures of the four metal(?)complexes were determined by X-ray single crystal diffraction methods,and the structural characterizations and properties of the complexes were investigated by elemental analyses,infrared spectroscopy,UV-vis absorption spectroscopy,Hirshfeld surfaces analyses,and Density Functional Theory(DFT).In recent years,the problems caused by industrial production have become more and more serious,and heavy metal ion pollution and highly toxic anion pollution have brought serious environmental problems to human society.Therefore,chemical sensors have been widely studied and are receiving more and more attention in environmental and biological fields.Meanwhile,two bis(half-salamo)-type fluorescent chemosensors,H₂L³ and H₂L⁴,were designed and their ion recognition performance and recognition mechanism were investigated.The main contents of this thesis are divided into the following parts:1.The asymmetric salamo-type ligand H₂L¹ was designed,and single crystals of its three complexes with different coordination modes were synthesized.The structures of the ligand H₂L¹ and its Cu(?),Co(?)and Ni(?)complexes were determined by ¹H-NMR spectroscopy,X-ray crystal diffraction and other characterization means.The Cu(?)complex is formed by coordination of the ligand H₂L¹ with Cu(?)atom in a 1:1 ratio,and the central Cu(?)atom possesses a tetra-coordinated twist quadrilateral geometry.The Co(?)complex is formed by coordination of the ligand H₂L¹ with Co(?)atom in a 2:2 ratio,and the central Co(?)atoms adopt penta-coordinate triangular bipyramidal geometries.The Ni(?)complex is formed by coordination of the ligand H₂L¹ with Ni(?)atom in a 2:3 ratio,and all the Ni(?)atoms bear hexa-coordinate octahedral geometries In addition,experiments on the antibacterial activities of the ligand H₂L¹ and its Cu(?),Co(?)and Ni(?)complexes were carried out,and it was found that the ligand H₂L¹ and its Cu(?),Co(?)and Ni(?)complexes inhibit Escherichia coli and Staphylococcus aureus to different degrees.2.The asymmetric salamo-type ligand H₂L² was designed,and single crystals of its Cu(?)complex were grown up.The structure of the Cu(?)complex was determined by elemental analyses and X-ray crystal diffraction method,etc.The Cu(?)complex is formed by coordination of the ligand H₂L² with Cu(?)atom in a 2:2 ratio,and the central Cu(?)atoms possesses penta-coordinate square-pyramid geometries.Calculations were carried out using Density Functional Theory(DFT)and the energy levels of the corresponding orbitals were derived.In addition,the Hirshfeld surfaces of the Cu(?)complex were analyzed.3.A novel bis(half-salamo)-type sensor molecule H₂L³ was designed and synthesized,and characterized by ¹H-NMR spectroscopy,mass spectrometry and fluorescence spectroscopy.The O-phenanthroline unit was first introduced into salamo structure,and make H₂L³ with two N₃O-donor cavities.Unlike the conventional N₂O₂-donor cavities,the introduction of N atoms with strong coordination abilities makes the coordination mode more novel.The sensor H₂L³can recognize Cu²⁺well by fluorescence spectroscopy and recognize HPO₄^2-and H₂PO₄?continuously after the formation of the Cu(?)complex.The recognition mechanism of the sensor was verified by the results of mass spectrometry and DFT calculations.4.A novel bis(half-salamo)-type sensor molecule H₂L⁴ was designed and synthesized,and characterized by ¹H-NMR spectroscopy,¹³C-NMR spectroscopy,mass spectrometry and fluorescence spectroscopy.The sensor H₂L⁴ can identify Cu²⁺and Co²⁺by the phenomenon of fluorescence quenching,which is confirmed by the remarkable effect of test strip experiments,and then Cu²⁺and Co²⁺can be distinguished by the change of solution color.Secondly,L⁴-Cu²⁺complex can continuously recognize both anions,HS?and PPi.The fluorescence turn-on of the probe H₂L⁴ can be clearly observed under UV light.Similarly,HS?and PPi can be distinguished by the change of solution color.The optimal coordination ratio between the probe H₂L⁴ and various ions was analyzed by fluorescence titration,Job's working curve,and mass spectrometry data,and the possible recognition mechanism of the probe was speculated.This provides experimental basis for the design and development of novel sensors for environmental detection.