多酸基单分子磁体的设计、合成、结构及性质研究

Single-molecule magnets (SMMs), which are capable of exhibiting magnetic bistability and present unique quantum properties, have a range of potential applications in nanoscience including formation storage and molecular spintronics. They currently receive growing attention in a wide area of science including chemistry, materials science and physics. According to the different constituent metal elements, to date, the pure transitional metal (TM)-, lanthanide (Ln) or actinide (Ac)-, TM/Ln or TM/Ac mixed-constructing SMMs can be distinguished. Polyoxometalates (POMs) are a remarkable class of inorganic compounds with enormous structural and compositional diversity and potential applications in various fields, such as catalysis, analytical chemistry, magnetism, nanotechnology, and medicine. However, in contrast with the research of metal-organic ligands-containing SMMs, POMs-based SMMs are still in their infancy. Herein, the project aims to obtain crystallized materials with SMMs properties by reacting POMs used as the precursor with TM and Ln or Ac ions, complexes with SMM behavior. As known, polyoxoanions (POAs) can be considered as inorganic, rigid ligands and are easy to define coordination geometry of metal ions, and hence limit their connection types and magnetic actions. Meanwhile, there are so many coordination oxygen atoms on POMs’ surface that they can react with multiple metal atoms, and other functional groups to form compounds with complex function. Furthermore, it is easy for POMs to form crystals suitable for exploring the correlation of structure and property. In conclusion, our research of POMs-based SMMs not only provides valuable references for the study of this field, but also has promising applied prospects.

由于单分子磁体在信息存储和处理等方面具有潜在的广泛应用前景而日益成为化学、材料学和物理学等学科的研究热点。按照构成单分子磁体的金属元素的不同，可将单分子磁体分为由纯过渡金属、稀土元素和过渡金属-稀土元素构成的三类化合物。与金属-有机配体构成的单分子磁体研究相比，多酸基单分子磁体的研究尚处于起步阶段。本项目以多酸为前驱体，分别与具有单分子磁体性质的配合物、稀土离子和过渡金属离子反应，制备具有单分子磁体性质的化合物，以期得到具有单分子磁体性质的晶态材料。由于多酸阴离子可以作为无机刚性配体，易于限定金属离子的配位构型，进而限定其连接方式和磁性作用；同时其表面配位氧原子多，易于和多个金属原子及其他功能性基团结合形成具有复合功能的化合物；而且多酸易于形成晶体，便于探索化合物结构与性质的相关性。因此，开展多酸基单分子磁体的研究，不仅具有重要的理论意义，而且还具有广阔的应用前景。

单分子磁体在信息存储和处理等方面具有广泛应用前景，该领域的研究成为化学、材料学等领域的研究热点。与有机配体构成的单分子磁体研究相比，多酸基单分子磁体的研究还很少。本项目以多酸阴离子为前驱体，利用阴离子表面具有丰富的氧原子，易于和多个金属原子及其他功能性基团结合形成具有优良功能性化合物的特点，将其作为无机刚性配体，用于限定金属离子的配位构型，进而限定其连接方式和磁性作用，将其与稀土及过渡金属离子配位，得到了多个新颖的多酸基单分子磁体化合物，系统研究了化合物的单分子磁体行为，拓宽了多酸类化合物潜在的应用领域，丰富了单分子磁体化合物的种类，在单分子磁体化合物的设计、合成等方面具有一定的理论意义。主要研究成果如下：.一、新型杂化稀土夹心型砷钨氧簇的合成及单分子磁体行为. 以K14[As2W19O67(H2O)]为前驱体，制得具有单分子磁体性质的杂化稀土夹心型砷钨氧簇K20Li2[Dy3(μ3-OH)(H2O)8(AsW9O33)(AsW10 O35(mal) )]218H2O。 .二、六聚锰桥连六铌取代Dawson结构化合物的合成及单分子磁体行为. 以六缺位Dawson结构磷钨酸盐出发，制得阴离子为[H34(Nb6P2W12O62)6 {MnIII3(OH)3 (H2O)6}4{MnII0.5Na0.5 (OH)0.5 (H2O)3.5}4]10-的化合物，这是迄今为止最大的Dawson结构聚阴离子，该化合物具有单分子磁体性质。 .三、有机膦酸参与构筑的砷钨氧簇稀土化合物的合成及磁性.从K14[As2W19O67(H2O)]出发， 制得有机膦酸(ATMP)参与构筑的单分子磁体化合物Cs9K7H5{[Dy2(H2O)5W4O6 (H2O)2(OH)(AsW9O33)3]2 (N(CH2PO3) 2)}∙23H2O。 .四、双酒石酸根桥连的单稀土取代磷钨酸盐的合成及磁性 .从K14[P2W19O69(OH2)]·24H2O出发，制得具有单分子磁体性质的双酒石酸根桥连的单稀土取代磷钨酸盐[N(CH3)4]6H10[Dy(C4H2O6)(α-PW11O39)]227H2O。.五、Keggin结构稀土双取代四聚阴离子的合成及磁性. 从多酸前驱体出发，得到阴离子为[(Dy2PW10O38)4W3O8(H2O)2(OH)4)]22-具有单分子磁体行为的化合物.