Synthesis, Structure, Fluorescent And Magnetic Properties Of The Lanthanide Complexes

As the optical, electric, magnetic and catalytic materials storehouse of raw materials, rare earth elements has aroused great interest and attention in the study of materials sciences. In addition, carboxylate-substituted tetrazolate ligands, possessing the carboxylate and tetrazole group, can act as a class of excellent polydentate ligands, which have been utilized in construction of coordination polymers with structural varieties and novel performance. This kind of complexes have potential use in optical materials, magnetic materials, as well as hydrogen storage materials. Series of lanthanide complexes based on tetrazole-1-acetic ligand have been prepared by hydrothermal reaction, we focus on exploring their fluorescence and magnetic properties. This paper consists of four parts:Chapter 1is introduced the literatural background of this paper,containing the research of azd coordination and carboxylic coordination and rare earth complex. While, the research significance and main conclusions of this thesis are summarized.Chapter 2, chemicals, instrument and experimental condition in this paper are introduced.Chapter 3, synthesis, structure and properties of the complexes. A series of lanthanide complexes based on tetrazole-1-acetic ligand and 2,2’-bipyridine as auxiliary ligand have been prepared with the formulas [Ln₂（tza）₄（NO₃）₂（2,2’-bipy）₂]（1Ln） [Ln = Dy 1, Sm 2, Eu 3, Tb 4, Gd5], [Ln₂（tza）₄（NO₃）₂（2,2’-bipy）₂]（2Ln） [Ln = Yb 6], [Ln₂（tza）₄Cl₂（2,2’-bipy）₂]（3Ln） [Ln = Dy 7],[Ln₂（tza）₂（NO₃）₄（2,2’-bipy）₂]（4·Ln）) [Ln = Nd 8, Sm 9, Eu 10, Gd 11, Tb 12, Dy 13], [1-tza =tetrazole 1-acetic, and 2,2’-bipy = 2,2’-bipyridine] and characterized by single-crystal X-ray diffraction, IR spectroscopy and elemental analyses. 1Ln, 2Ln, 3Ln and 4Ln show similar dinuclear structures. Variable-temperature magnetic susceptibility of complexes were measured except for Gd 11 and Tb 12. Furthermore, both Dy 1 and Dy 7 display frequency-dependent ac magnetic susceptibilities which indicate slow relaxation of the magnetization typical of single-molecule magnet（SMM） behavior, but Dy 13 with a more symmetrical symmetry showed no SMM property. The room-temperature photoluminescence spectra of complexes Dy（1 and 7）,Sm（2 and 9）, Tb（3 and 12）, Eu（4 and 10） andexhibit strong characteristic emissions in the visible region, whereas Yb 6 and Nd 8 show NIR luminescence. In addition, thermogravimetric analyses（TGA） of compounds Sm 2, Yb 6 are also investigated.Chapter 4, synthesis and structure of two dimensions expansion of lanthanide complexes with the formulas [Dy₄（m₃-OH）₄（tza）₄（ClO₄）₄（H₂O）₆][H₂O] Dy 14 and [H₃O]₂[Sm₄（m₃-O）₄（tza）₆（H₂O）₅]Sm 15, tetrazole 1-acetic as ligand, without auxiliary ligand, wo dimensional layered compounds were obtained, which constructed by [Ln₄（m₃-OH）₄] and [Sm₄（m₃-O）₄] clusters, respectively.