发光稀土金属-有机骨架材料的设计合成及性能研究 - 图文

摘要

在过去的二十多年里，金属-有机骨架（MOFs）材料作为一类新型的分子基多功能材料，由于其兼具有多孔性、比表面积大、可剪裁、可设计、易功能化等特点，在光、电、磁、气体存储和分离、催化剂、传感器以及手性拆分等诸多领域均表现出了巨大的应用前景，受到了学术界和和工业界越来越多的关注。羧酸类配体配位方式灵活多样且配位能力强，由它构筑的金属-有机骨架材料已经成为当前配位化学研究的热点。由于镧系元素的电子结构中都有一个没有完全充满的4f 电子层，且各种镧系元素4f 层电子数的不同，这组元素的每一个元素又都具有各自特别的性质，特别是光学和磁学性质。近十几年来，镧系元素被越来越多的化学工作者选作金属有机骨架材料的金属中心。本论文采用对苯丙二烯酸和9,9-二甲基芴-2,7-二羧酸两种二羧酸配体分别与多种镧系金属盐，通过分子水热及溶剂热方法合成得到了12种结构新颖且具有独特发光性能的配位化合物。通过X-射线单晶衍射、粉末 X-射线衍射、元素分析、热重分析、荧光光谱和红外光谱等手段对晶体结构和光学性能进行了研究。具体成果概括为以下三点:

1. 以对苯丙二烯酸作为桥联配体，利用溶剂热法，与镧系金属离子进行配位自组装，设计合成得到了三种具有新颖结构的多孔配位聚合物，[Ln2(pda)2(HCOO)(OH)(H2O)]n (Ln = Dy, 1;Tb, 2; Ho, 3；H2pda 即为对苯丙二烯酸)，X-射线单晶衍射和粉末衍射表明它们是同构的，稀土离子同羧酸氧原子形成一系列平行的Ln-O棒状二级结构单元，对苯丙二烯单元桥连这些二级结构单元形成pcu（α-Po）类型的棒状堆积三维骨架。我们在室温下研究了配合物1-3的发光性质，它们在固态下都表现出强的蓝光发射。由于配合物中络合作用的存在，与配体H2pda发光相比，配合物表现出了强的荧光增强现象，特别是配合物1的荧光发射。

2. 以9,9-二甲基芴-2,7-二羧酸作为桥联配体，利用溶剂热法，与镧系金属离子进行配位自组装，设计合成得到了五个具有新颖结构的多孔配位聚合物，[Ln3(MFDA)4(NO3)(DMF)3]n (Ln = Eu, 4;Sm, 5; Dy, 6; Tb, 7; Ho, 8；H2MFDA 为9,9-二甲基芴-2,7-二羧酸)，结构表征发现它们是同构体，具有pcu类型的棒状堆积三维结构，尺寸大约为9.0 × 5.0 ?2的一维菱形孔道贯穿其中。孔道被配位的DMF分子占据，这些DMF可以通过加热去除。荧光光谱显示配合物5-8具有蓝光发射，而配合物4具有很强的三价铕离子特征的红光发射。荧光猝灭实验表明配合物4对硝基爆炸物和铁（III）离子具有荧光猝灭传感作用。

3. 利用9,9-二甲基芴-2,7-二羧酸配体和镧系金属离子，在不同的溶剂热条件下，设计合成得到了四个具有柔性特征的多孔配位聚合物，{[Ln2(MFDA)2(HCOO)2(H2O)6]·H2O}n (Ln = Eu, 9; Dy, 10; Tb, 11; Ho, 12；H2MFDA 为9,9-二甲基芴-2,7-二羧酸)，结构表征发现它们是同构体，

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具有pcu类型的棒状堆积三维结构，一维菱形孔道贯穿其中，孔道被游离和配位水分子占据。三维骨架在部分或完全失水过程中会沿着c轴可逆收缩和膨胀，与此同时一维菱形孔道也相应的变窄或变大。荧光光谱显示配合物10-12具有蓝光发射，而配合物9具有很强的三价铕离子特征的红光发射。荧光猝灭实验表明配合物9对苦味酸和铁（III）离子具有荧光猝灭传感作用。

关键词: 金属有机骨架材料，溶剂热合成，镧系金属离子，对苯丙二烯酸，9,9-二甲基芴-2,7-二羧酸，晶体结构，荧光，传感

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Abstract

In the past two decades，metal–organic frameworks (MOFs) emerged as as a new class of multifunctional materials. The coexistence of intrinsic porosity,high surface area,Easy functionalization, flexible tailor and decoration enables their applications in a variety of ?elds such as luminescence,magnetism, gas storage and separation，catalysis，sensor ，chiral separation and so on. They have attracted more and more attention of not only the academic field but also the industrial field. Carboxylic acid ligands can coordinate in various ways and their coordination ability are quite strong. In recent years metal organic framework material by constructed by Carboxylic acid ligands has gradually become a hot topic in the field of coordination chemistry. The lanthanides have a not completely filled 4f electron shell and various lanthanoid the 4f electron numbers are different.So Every lanthanoid has their own special properties, especially optical and magnetic properties. Over the last decade, the lanthanides were selected as metal centers of the metal-organic frameworks by more and more chemical workers. In this thesis, p-phenylenediacrylic acid and homemade 9,9-dimethyl-?uorene-2,7-dicarboxylic acid are used as bridging ligand and lanthanoid were used as metal centers. With self assemble theory,we synthesized twelve new metal–organic frameworks. These complexes (1-12) were characterized by single crystal X-ray diffraction,powder X-ray diffraction, elemental analysis,thermogravimetric analysis and IR spectrum. The fluorescent properties of the complexes were studied. The main contents of this thesis are summarized as follows: 1.

Based on p-phenylenediacrylic acid and lanthanoid, we synthesized three new metal–organic

frameworks under solvothermal condition, [Ln2(pda)2(HCOO)(OH)(H2O)]n (Ln = Dy, 1;Tb, 2; Ho, 3；H2pda = p-phenylenediacrylic acid). We found that they are isostructural by structural characterization. They all possess a 3D architecture with the pcu net topology based on the parallel 1D lanthanide–oxygen rod-shaped secondary building units. The photoluminescent properties of 1–3 have been investigated at room temperature. Complexes 1–3 all display the intense blue emission in the solid state. Especially, compared with the free H2pda ligands, complex 1 shows the strong ?uorescence enhancement due to the complexation. 2.

Under solvothermal conditions, we use 9,9-dimethyl-?uorene-2,7-dicarboxylic acid,

lanthanoid and synthesiz five new metal–organic frameworks, [Ln3(MFDA)4(NO3)(DMF)3]n (Ln = Eu, 4;Sm, 5; Dy, 6; Tb, 7; Gd, 8；H2MFDA = 9,9-dimethyl-?uorene-2,7-dicarboxylic acid). They

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were structurally characterized by single-crystal X-ray di?raction. They are isostructural. They are three-dimensional coordination polymer with pcu type rod-packing structure, through which 1D rhombic channels penetrate. We studied their thermal stability and luminescence properties. Especially the potential of Complex 4 for nitro explosive and Fe3+ ion sensing is studied through luminescence quenching experiments, which show that Complex 4 is a potential luminescent sensory material for both nitro explosives and Fe3+ ion. 3.

Also we use 9,9-dimethyl-?uorene-2,7-dicarboxylic acid and lanthanoid, under different

solvothermal conditions with the above,we afforded four new metal–organic frameworks, {[Ln2(MFDA)2(HCOO)2(H2O)6]·H2O}n (Ln = Eu, 9; Dy, 10; Tb, 11; Gd, 12；H2MFDA = 9,9-dimethyl-?uorene-2,7-dicarboxylic acid). Structural characterization shows that they are isostructural. They possesses the three-dimensional pcu type rod-packing structure with one-dimensional rhombic channels. The framework of them can reversibly shrink/swell along the c axis upon partially/fully release of the water molecules. We also studied the thermal stability and luminescence properties of complexs 10-12. The potential of Complex 9 for Fe3+ and PA sensing was studied in DMF through the luminescence quenching experiments, which shows Complex 9 is a potential turn-off luminescent sensory material for the selective detection of Fe3+ ion and PA.

Key words: metal–organic frameworks, solvothermal synthesis, lanthanide, p-phenylenediacrylic acid, 9,9-dimethyl-?uorene-2,7-dicarboxylic acid, crystal structures, luminescence, sense

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