Investigations On Luminescent And Magnetic Function-Directed Lanthanide-Based Complexes

Recently,the construction of functional coordination complexes has been one of the research hotspots for scientists.We summarized the published works on magnetism?including single-molecule magnet?SMM?and molecular magnetic refrigeration?and luminescence.From the crystal engineering,fourteen lanthanide complexes have been synthesized driven by the optical and magnetic properties.Using the single crystal X-ray diffraction,elemental analysis,IR,PXRD,TG,UV-vis,luminescent spectra and magnetic measurements investigated these complexes.The main contributions in this dissertation are as below:1.Seven dinuclear complexes based on 2-[?4-chloro-phenylimino?-methyl]-8-hydroxyquinoline ligand?HL1?,[RE2?hfac?₄?L1?₂]?RE = Y?1?,Gd?2?,Tb?3?,Dy?4?,Ho?5?,Er?6?and Lu?7?;hfac-= hexafluoroacetylacetonate?,have been synthesized,structurally and magnetically characterized.Complexes 1-7 have similar dinuclear structures,the luminescence spectra indicate that complex 3 exhibits characteristic Tb3+ ion luminescence.The magnetic studies reveal that 2 features magnetocaloric effect with the magnetic entropy change of-?Sm = 16.83 J kg-1 K-1 at2 K for ?H = 8 T,and 4 displays slow magnetic relaxation behavior with the anisotropic barrier of 6.7 K and pre-exponential factor ?0 = 5.3 � 10-6 s.2.Three dinuclear complexes based on 2-[?4-methoxyl-phenylimino?-methyl]-8-hydroxyquinoline ligand?L2?,[Y₂?hfac?₄?L2?₂]?8?,[Y₂?dbm?₄?L3?₂]?9?and[Y₂?dbm?₄?L2?₂]?10?,have been synthesized.Complexes 9 and 10 behave different structures because of the different solvent used in the synthetic process.The luminescence spectra indicate that 8-10 show L2 ligand luminescence.3.Four lanthanide-nitronyl nitroxide radical complexes based on2-?3-methylthiophene?-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide?L4?,[Ln?hfac?₃?L4?₂]?Ln = Pr?11?,Tb?12?,Dy?13?,Ho?14??,have been synthesized,and structurally and magnetically characterized.The single-crystal X-ray diffraction show that complexes 11-14 have similar mononuclear tri-spin structures.The luminescence emission spectrum of complex 12 in methanol solution shows characteristic Tb3+ centered luminescence.Furthermore,the variable-temperature magnetic susceptibility studies reveal the antiferromagnetic interactions between Ln3+ions and radicals in complexes 11,12 and 14,while ferromagnetic interactions in complex 13.