Study On The Synthesis,luminescent And Magnetic Properties Of The Lanthanide Complexes Based On ?-diketone Ligands

Recently,the study of optic/magnetic molecular materials remains of considerable interest due to their various potential applications in the field of large scale memory devices,optoelectronic devices and biological systems.The lanthanide ions have the high luminescent efficiency and high color purity,making them more useful in display devices,luminescent probes in biology and tunable lasers.Moreover,Ln?III?ions,especially Dy?III?ion with its⁶H_15/2 ground state,possess highly magnetic anisotropy arising from high spin–orbit couplings and unquenched orbital angular momentums,being an suitable spin carrier for constructing single-molecule magnets?SMMs?or single-ion magnets?SIMs?with high energy barriers(U_eff)and blocking temperature?T_B?.The design and synthesis of multifunctional materials with luminescent and magnetic properties is a fertile topic of research in the field of molecular materials.In this paper,we adopt different?-diketone ligands to construct nine lanthanide complexes by selecting different lanthanide ions and reaction conditions.The luminescence and magnetic properties of these complexes were studied through a series of measurements and characterizations,while their structure-property relationships were further analysized based on respective single crystal structure.In chapter 1:we introduced the photoluminescence of lanthanide complexes,the near-infrared emission of lanthanide ions,the research progress of single-molecule magnets in brief,and simply described the background and significance of this thesis.In chapter 2:?1?through the hydrolysis reactions of the Tb?III?and Sm?III?salts controlled by the same dibenzoylmethane?Hdbm?ligand in CH₂Cl₂/n-C₆H₁₄ mixed solvents,two new Ln?III?clusters[Tb₅??₃-OH?₄??₄-OH??dbm?₁₀]·2H₂O?1?and[Sm₄??₃-OH?₄?dbm?₁₀]·12H₂O?2?with different nuclearity were obtained under the identical reaction conditions.Different nuclearity is attributed to the effect of lanthanide contraction.?2?through the hydrolysis of the Er?III?and Yb?III?salts controlled by the same acetylacetone?Hacac?ligand in toluene solution,two novel tetranuclear clusters with the formula of Ln₄??₃-OH?₄{??-O?-?²-acac}₄??²-acac?₄]·C₇H₈?Ln=Er 3,Yb 4?,showing cubane-like geormetry,were obtained.The luminescent and magnetic properties of complexes 1,2,3 and 4 have been studied systematically.Their structure-property relationships were further studied based on respective single crystal structure.In chapter 3:?1?using dibenzoylmethane?Hdbm?to react with ErCl₃·6H₂O,the precursor Er?dbm?₃·2H₂O was synthesized.Subsequently,employing chiral bis-bidentate N-donor ligand,?–?-pinene pyrazine derivative?L_R?,as a bridging ligand for Er?dbm?₃·2H₂O,and depending on the ratio control of reactants,two mono-and dinuclear homochiral Er?III?complexes with the formulae Er?dbm?₃L_R·2H₂O?5?and Er₂?dbm?₆ L_R·6H₂O?6?have been synthesized and structurally characterized.?2?Using Nd?III??-diketones precursor Nd?dbm?₃·2H₂O to react with bis-bidentate chiral enantiomers containing N atoms,?–?-pinene pyrazine derivative?L_R?and?+?-pinene pyrazine derivative?L_S?respectively,only a pair of mononuclear enantiomers Nd?dbm?₃L_R·2H₂O?7?and Nd?dbm?₃L_S·2H₂O?8?were synthesized due to the effect of lanthanide contraction.Their chiroptical activities,Near-infrared luminescent and magnetic properties have been characterized.Then the results were analyzed and discussed in detail.Their structure-property relationships were further discussed based on respective single crystal structure.In chapter 4:Based on heterocycle?-diketone 1-phenyl-3-methyl-4-acetyl-5-pyrazolonate?Hpmap?,a new acylpyrazolonate-based Dy?III?complex formulated as[Dy?pmap?₃?H₂O?₂]?CH₃COOC₂H₅??9?has been synthesized.Interestingly,this complex not only has excellent luminescent property but also shows the characteristics of single ion magnet with two-step slow magnetic relaxation behaviors.The multifunctional feature was further investigated in detail based on single crystal structure analysis.