【作者】 廖作雷；

【导师】 陈接胜；

【作者基本信息】 吉林大学 ， 无机化学， 2008， 博士

【摘要】 配位聚合物是晶体工程学的重要研究方向。近年来,关于过渡金属和镧系金属配位聚合物的研究已经非常广泛和深入,不但合成出了丰富的结构,而且还开发出了很多宝贵的性质,这些化合物在诸多方面展现出广阔的应用前景。然而,相比于过渡金属和镧系金属,目前对锕系元素配位化学的认识还比较少。铀是锕系元素的典型代表,对铀的研究有助于加深对这一系列元素的认识;同时,铀酰化合物也表现出丰富的结构多样性,和很多过渡金属和稀土金属所没有的特殊物理化学性质,铀的配位化学研究逐渐得到人们的重视。本文致力于功能铀酰化合物的构筑和性能研究。在水热条件下,制备了8个铀酰-有机配位聚合物。对其中的一个系列5个化合物,应用晶体工程学的策略,研究了配体的空间构型对化合物结构的影响。通过有目的的选择高空间位阻的配体,成功得到了3个具有三维骨架结构的产品,其中一个表现出微孔吸附性质。铀酰离子在该系列5个化合物中共形成了单核七配位、单核八配位以及3种不同构型的四核簇,体现了丰富的配位、成簇特点。另一系列3个化合物,主要从光催化性质方面进行了探讨,证明铀酰配位聚合物的光催化性质主要源于其中的铀酰中心,而银等过渡金属离子对催化性质没有明显的干扰;同时研究了光催化反应速率同体系中氧浓度的关系,这有助于理解光催化反应机理。此外,还在还原条件下,得到了一个稳定的四价铀磷酸盐化合物,初步研究表明该化合物具有上转换发光的性质。更多还原

【Abstract】 Crystal engineering is widely involved in the field of metal-organic coordination polymers, and is becoming a powerful strategy for rational structure construction and function improvement. As a result, the knowledge of synthetic chemistry is significant enriched, and a large variety of complex compounds are intruduced, with not only structural diversities but also promising potential applications, such as sorption and hydrogen storage, catalysis, enantiomeric discrimination, optics, magnets and sensors.In recent years, the transition and lanthanide metals are extensively studied in the field of coordination polymers. On the other hand, the actinide elements are less recognized. Among them, the uranium compounds are attracting increasing research efforts, because of their rich structure topologies and numerous properties.Series of uranyl-containing coordination polymers are obtained under hydrothermal conditions and studied from structural and functional perspectives. Meanwhile, a U（IV） phosphate compound is also synthesized and discussed. This thesis is completed by 4 chapters.In the introduction part （Chapter 1）, the development of coordination polymers are briefly reviewed, with major emphases on the uranyl compounds, including the synthesis and structures and photoluminescent and photocatalytic properties. Also the goals and achievements of this thesis are summarized.In Chapter 2, a series of 5 uranyl assembly compounds are introduced: （UO₂）₃（v-BTC）₂·4H₂O （1）, （UO₂）₆（OH）₂（m-BTC）₂（m-HBTC）₂（H₂O）₂·7H₂O （2）, （UO₂）₄O₂（m-BTC）₂（NC₂H₈）₂·H₂O （3）, （UO₂）₂O（H₂BTEC）（NHC₂H₆）₂·H₂O （4） and （UO₂）₃（H₂BTEC）₃·18H₂O （5）. The strategy is to employ the sterics between the carboxylate groups to give rise to three-dimensional connectivity of the ligands, in order to cross link the planar uranyl species into 3D frameworks. In fact, Compounds 1, 2 and 3 follow the prediction, and 3D structures are form for these three compounds. In 1, the structure is composed from isolated seven-coordinated and eight-coordinated uranyl sites connected by BTC linkers. In 2 the mononuclear uranyl centers and tetranuclear clusters coexist, and leads to 1D channels within the structure. Upon removal of guest molecules in the channels, 2 exhibits microporous sorption properties. All uranyl sites in 3 polymerize into the same tetranuclear clusters, and result in even larger channels than 2. But the removal of the guest species in 3 is not successful yet. The comparison of pore size between 2 and 3 reveals the relations between guest molecules and pore structures. Compounds 4 and 5 crystallize into layered structures. The uranyl units polymerize into tetranuclear clusters in 4 while stay as isolated monomers in 5. It is noticed that the ligand structure in not the only key to determine the product dimension. In fact, several factors cooperate to control the overall structure. Besides, all these 5 compounds exhibit typical uranyl fluorescent emission.In Chapter 3, a series of 3 compounds are synthesized in association with NDC and bipyridine ligands: （UO₂）₈（NDC）₁₂（4,4’-bipyH₂）₃（4,4’-bipyH）₃ （6）, （UO₂）₃O[Ag（2,2’-bipy）₂]₂（NDC）₃ （7） and （UO₂）₂（NDC）₂（2,2’-bipy）₂ （8）. 6 and 7 are layered compounds. The layers of 6 are constructed from seven-coordinated uranyl monomers and NDC linkers. In 7 it consists of both tetranuclear clusters and monomers. The apertures within the layers packed into channels, which are filled with 4,4’-bipy species and Ag（2,2’-bipy）₂⁺ complex ions for 6 and 7, respectively. In 8 both NDC and 2,2’-bipy ligands coordinate to uranyl centers, and results in a 1D chain structure. The photocatalytic activities of 6 and 7 are compared, and the results proves the photocatalytic property is contributed by uranyl ions along, while the Ag（2,2’-bipy）₂⁺species have little contribution to this property. The correlations between photocatalytic degradation rate and oxygen concentration are also elucidated. The photocatalytic degradation reaction is very sensitive to oxygen at low oxygen level. With rising O₂ concentration, the photocatalytic degradation accelerates but at descending rate. This phenomenon is in good agreement with the proposed photo- catalytic degradation mechanism.Nowadays the research of uranium compounds expands to uranium-inorganic framework and low valence uranium compounds. Compared to the U（VI） families, the low valence uranium compounds may exhibit interesting properties because of their electron configurations of uranium ions. In a ethylenediamine-phosphoric acid system, a uranium（IV） phosphate layered compound U₃（PO₄）₆（H₂en）3 （9） is obtained both form direct one-pot reaction or pre-reduction process. The uranium ions are in slightly distorted octahedron environment, and are stable to air or moisture. Further study reveals the up-conversion fluorescent emission of 9.更多还原