Study On Synthesis,Characterization And Properties Of Novel Polydentate Chelate Ligands And Their Complexes

Polydentate chelate ligands often have a strong ability of coordination,great flexibility and special space-steric effect,as a result,the structure of corresponding complexes show diversification,and there will be fluorescence,magnetic,biological activity and many other excellent performance.Design and synthesis of appropriate and good selective polydentate chelate ligands,reaction with different metal ions,synthesize novel and versatile complexes by changing the reaction conditions and other factors.Studying the relationship between the structure and properties of complexes has great significance on the research of coordination chemistry and the design of new functional materials.In this paper,two kinds of different substituents salicylamide Salen-like ligands has been designed and prepared,which characterized by elemental analysis,1H NMR,infrared spectrum,then synthesized seven rare-earth metal complexes 1-7,which characterized by infrared spectrum,ultraviolet spectrum,fluorescence spectrum and X-ray single crystal diffraction.Discussed the different substituent of ligands on the influence of the structure of complexes,further studied the fluorescence properties of the complexes and the effect between structure and properties.1.A brief overview of the recent advances in polydentate chelate ligands and their rareearth complexes,as well as the application of fluorescent probes.2.The ligands H₃L¹ and H₃L² were synthesized by N-aminoethyl salicylamide as the central skeleton reaction with 5-nitro salicylaldehyde and 4-diethylamino salicylaldehyde respectively.Prepared a series of dinuclear rare-earth complexes [Ln₂?H₂L¹?3-?NO₃?₃]·3CH₃CN[Ln=Nd?1?,Sm?2?,Eu?3?],[Ln₂?H₂L²?₂?NO₃?₄]·2CH₃CN[Ln=Eu?4?,Er?5?,Tm?6?,Yb?7?].The crystal structures of ligands and complexes were characterized and discussed the effects of different substituents on the structure of the complexes.the ligands involved in this section are as follows:H₃L¹ 1-?2-hydroxy-benzamido?-2-?2-hydroxy-5-nitro-benzylideneamino?-ethane H₃L² 1-?2-hydroxy-benzamido?-2-?2-hydroxy-4-diethylamino-benzylideneamino?-ethane3.The spectral properties of the complexes were further studied.Studies have shown that ligands H₃L¹,H₃L² can act as antenna ligands,effective sensitized rare earth fluorescence.In addition,Eu₂?H₂L¹?₃?NO₃?₃]·3CH₃CN?3?can recognize Al³⁺ sensitively and highly selectively in acetonitrile solution.And discussed the effect of the complexes structure on its properties.4.Results and Prospects: Based on the study of the structure and fluorescence properties of the two ligands and their complexes,the effects of ligand structure on the structure and properties of the complexes were summarized.The research results of this paper enrich the research of rare earth luminescence complexes,and have some guiding significance for the study of the structure-property relationship of the complexes.