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Title:
基于苄胺类柔性配体与功能化配体的金属-有机骨架材料的合成、结构及其性能研究
Author: 王超
Degree Level: 博士
Issued Date: 2016-04
Degree Grantor: 中国科学院大学
Place of Degree Grantor: 北京
Supervisor: 李学兵 ; 赵学波
Keyword: 金属-有机骨架材料 ; 柔性配体 ; 阀门效应 ; 单晶-单晶结构转变 ; CO2吸附与分离 吸附与分离
Subject: 化学工程
Major: 工学
Abstract: 金属-有机骨架(MOFs)材料作为一种新型的有机-无机杂化配位聚合物具有结构规则、结构多样化、结构可设计、孔道可功能化、刚/柔性可调节等众多优点,并使其在气体存储、气体分离、荧光、催化以及磁性等众多领域展现出一定的应用潜力。通常来说实现MOFs结构和性质多样性的途径包括不同配体与金属中心的选择、合成工艺条件的调节、后合成修饰、柔性配体的引入、第二配体的引入以及功能化配体的引入等。其中,引入柔性配体可使配体与金属离子配位时具有一定的构象自由度并带来多样化的配位取向。第二配体的引入可以增加金属中心的配位方式并使不对称结构单元的组成发生变化。功能化配体构建出的骨架由于官能团的引入可使整体结构发生不同程度的变化并带来性能上的改善。本文从以上三点出发,设计并合成了多种新颖结构的MOFs材料,在实现MOFs结构多样性的同时,分别探索了各种MOFs材料在气体吸附、气体分离和荧光等方面的性质。 首先,合成了一系列柔性并具有三重穿插网络的镧系MOFs材料[Ln(HL)(DMA)2]•DMA•2H2O(Ln = La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy和Er;DMA = 二甲基乙酰胺;H4L = 2,3,5,6-四甲基-1,4-二(5-苄胺-1,3-间苯二甲酸)。[Sm(HL)(DMA)2]•DMA•2H2O(QI-Sm)作为该系列材料的代表被进一步研究。活化后的样品Sm(HL)(DMA)2(QI-Sm-a)在吸附/脱附过程中展现出可逆的单晶-单晶结构转变特征。完全负载CH2Cl2的QI-Sm-a具有类似于QI-Sm的结构和孔体积。单晶X射线衍射结果显示QI-Sm到QI-Sm-a的活化过程中发生如下变化:一个配位的DMA分子转动到孔道内部,即由反式配位变为顺式配位;晶胞体积缩小约20%;孔隙率减小到3.5%。分别从结构、热力学和动力学角度探索该阀门效应。吸热的开门过程的动态结构响应受吸附焓和骨架结构演变过程中沿孔道的菲克扩散所驱动。由于分子阀门效应的影响,相比于CH4、H2、O2和N2等气体,高压下QI-Sm-a对CO2气体显示出极高的选择性。QI-Sm的可逆性和选择性的分子阀门特征使其在气体分离和分子识别等领域具有潜在的应用价值。 其次,在溶剂热条件下分别合成了三种新颖的MOFs材料,即[Zn2(L)(H2O)]•3DMF•1.5H2O(QI-Zn-1), [Zn2(L)(4,4'-bpy)1.5(H2O)2]•2DMF•2H2O(QI-Zn-2)和 [Zn2(L)(2,2'-bpy)2(DMF)2]•2DMF•4H2O(QI-Zn-3)(H4L = 2,3,5,6-四甲基-1,4-二(5-苄胺-1,3-间苯二甲酸;4,4'-bpy = 4,4'联吡啶;2,2'-bpy = 2,2'联吡啶;DMF = 二甲基甲酰胺)。分别利用单晶X射线衍射、元素分析、红外光谱、粉末X射线衍射以及热重分析等表征手段对其理化性质进行表征。由于吡啶类第二配体的引入,三种MOFs材料中的L4-采取了不同的配位模式,并使晶体结构显示出多样化特征。QI-Zn-1由第二结构单元[Zn2O(COO)4]与H4L组装而成。二者分别作为4连接节点使得骨架整体表现为(4,4)连接的pts型网络。该骨架孔隙率高达54.6%。QI-Zn-2由两种晶体学独立的Zn(II)金属中心、H4L和4,4'联吡啶组装而成,并展现出一种未曾报道的四节点(3,4,4,4)型网络。QI-Zn-3由a方向彼此平行的一维分子链堆积而成,并具有7.8 ×10.4 Å2的一维孔道。分子链通过氢键作用连接成二维分子层。三种化合物的热力学性能和荧光性能同样被进一步研究。 最后,设计并合成了一种甲基/羟甲基功能化的MOFs材料[Cu(L)(H2O)]•1.5DMA•0.5H2O(QI-Cu)(H4L = 2,5-二羟甲基-3,6-二甲基-1,4-二间苯二甲酸;DMA = 二甲基乙酰胺)。作为NOTT-101的一种变体材料,QI-Cu在常温常压下显示出极好的CO2和CH4吸附性能。1 bar和293 K下QI-Cu的CO2吸附量高达4.56 mmol g-1,这一数值在已报道关于CO2吸附的MOFs材料中居于前列,同时该数值明显高于未功能化的NOTT-101(3.93 mmol g-1)。功能化的QI-Cu的CO2和CH4吸附焓也均高于NOTT-101。利用单组份气体吸附等温线进行理想吸附溶液理论模拟并对混合组分吸附进行预测。结果证明QI-Cu具有更高的CO2/CH4和CO2/N2选择比。此外,甲基与羟甲基的引入显著提高了QI-Cu的水稳定性。 本文通过苄胺类柔性配体、功能化配体的设计与合成以及第二配体的引入,实现了MOFs结构和性质的多样性,并对晶体工程、CO2捕获以及CO2分离等领域具有一定贡献。其中,最为突出的理论创新在于首例含有配位分子门结构的柔性MOFs材料的合成并通过结构、热力学和动力学等角度对柔性MOFs中配位分子门机理和气体分离机理进行阐述。该机理的阐述对宏观数据与分子水平结构转变行为间关系的建立起到了重要作用。
English Abstract: Metal-organic frameworks (MOFs) are a subclass of novel organic-inorganic hybrid coordination polymers that show great potential for applications of gas storage and sequestration, luminescence, catalysis and magnetism due to their prodigious surface area, considerable structural diversity, tunable functional pore environment and adjustable rigid/flexible framework. Generally, the diversity of structure and property can be achieved by various approaches including appropriate choice of linker and node, adjustment of reaction conditions, post-synthesis modification, design of flexible ligands, introduction of colinkers and ligand functionalization. The incorporation of linkers with flexibility into the framework can make the linkers possess conformational freedom when coordinating with metal centers and result in various coordination orientations. Additionally, introduction of colinkers can also give rise to different coordination modes and change the composition of asymmetric unit. Furthermore, organic group functionalization in MOFs offers different levels of structural adjustments and improved properties. On the basis of the above considerations, several novel MOFs were designed and synthesized. In addition to achieving the structural diversity, the gas adsorption and separation and luminescence properties of them were also studied in detail. A series of flexible 3-fold interpenetrated lanthanide-based metal organic frameworks (MOFs) with formula [Ln(HL)(DMA)2]•DMA•2H2O (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Er; DMA = dimethylacetamide and H4L = 5,5'-(2,3,5,6-tetramethyl-1,4-phenylene)bis(methylene)bis(azanediyl)diisophthalic acid) were prepared. [Sm(HL)(DMA)2]•DMA•2H2O (QI-Sm) was studied as an exemplar of the series and activated Sm(HL)(DMA)2 (QI-Sm-a) exhibited reversible single-crystal to single-crystal (SCSC) structural transformations in response to adsorption and desorption of guest molecules. QI-Sm-a fully loaded with CH2Cl2 had a very similar structure and pore volume to QI-Sm. X-ray single crystal structural analysis shows that the activation of QI-Sm to form QI-Sm-a, involves one DMA molecule rotating into the interior of the channel with a change from trans to cis Sm coordination and unit cell volume shrinkage of ~20%, and a void volume of 3.5%. Structural, thermodynamic and kinetic aspects of the molecular gating mechanism were studied. The dynamic and structural response of the endothermic gate opening process is driven by the enthalpy of adsorption and Fickian diffusion along the pores produced during framework structure development. Exceptionally high CO2 selectivity was observed at elevated pressure compared with CH4, H2, O2 and N2 due to molecular gate opening of QI-Sm-a for CO2, but not for the other gases. The reversible and selective molecular gating characteristics of QI-Sm highlight potential sorption applications such as gas separation or molecular recognition. Three novel metal-organic frameworks (MOFs), [Zn2(L)(H2O)]•3DMF•1.5H2O (QI-Zn-1), [Zn2(L)(4,4'-bpy)1.5(H2O)2]•2DMF•2H2O (QI-Zn-2), [Zn2(L)(2,2'-bpy)2(DMF)2]•2DMF•4H2O (QI-Zn-3) (H4L = 5,5'-(2,3,5,6-tetramethyl-1,4-phenylene)bis(methylene)bis(azanediyl)diisophthalic acid; 4,4'-bpy = 4,4'-bipyridine; 2,2'-bpy = 2,2'-bipyridine; DMF = dimethylformamide) were synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). The L4- in three complexes display different coordination modes and the introduction of bipyridine colinkers brings significant structural variations into the frameworks. QI-Zn-1 is constructed from dinuclear carboxylate [Zn2O(COO)4] SBUs and H4L ligand, exhibiting a binodal (4,4)-connected pts net with 54.6% solvent-accessible void. QI-Zn-2 exhibits an unprecedented tetranodal (3,4,4,4)-connected net which is constructed by two types of crystallographically independent Zn(II) ions, H4L and the colinker of 4,4'- bipyridine. QI-Zn-3 is constructed by parallel 1D molecular ladders stacked along a-axis that generate 1D channels with size of 7.8 ×10.4 Å2 and hydrogen bonded to 2D layers. Their thermal stabilities and luminescent properties have also been studied in detail. A new methylol and methyl functionalized metal−organic frameworks (MOFs) [Cu(L)(H2O)]•1.5DMA•0.5H2O (QI-Cu) (H4L = 2,5-bis(hydroxymethyl)-3,6-dimethyl-1,4-diisophthalic acid; DMA = dimethylacetamide) were designed and synthesized. As a variant of NOTT-101, this material exhibits excellent CO2 uptake capacities at ambient temperature and pressure, as well as high CH4 uptake capacities. The CO2 uptake for QI-Cu is high up to 4.56 mmol g-1 at 1 bar and 293 K, which is top-ranked among MOFs for CO2 adsorption and significantly larger than the nonfunctionalized NOTT-101 of 3.93 mmol g-1. The enhanced isosteric heat values of CO2 and CH4 adsorption were also obtained for this linker functionalized MOFs. From the single-component adsorption isotherms, multicomponent adsorption was predicted using the ideal adsorbed solution theory (IAST). QI-Cu shows an improvement in adsorptive selectivity of CO2 over CH4 and N2 below 1 bar. The incorporation of methylol and methyl groups also greatly improves the hydrostability of the whole framework. The considerable structural diversity was achieved by the design and synthesis of flexible benzylamine-based and functionalized ligand and the introduction of colinkers, contributing to the research fields of crystal engineering, CO2 capture and CO2 separation. The most important contribution of the work described in this work lies in the fact that it is the first complete study of the structural, thermodynamic and kinetic aspects of a coordinated molecular gating mechanism in a flexible porous material. The detailed transport mechanism and the structure-function relationship of the porous materials have been elucidated and the critical gap between the macroscopic data and the transport behavior at the molecular level has been bridged.
Language: 中文
Department: 多相催化转化
Available Date: 2017-01-30
DOC Type: 学位论文
Content Type: 学位论文
URI: http://ir.qibebt.ac.cn/handle/337004/9760
Appears in Collections:多相催化转化团队_学位论文

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王超. 基于苄胺类柔性配体与功能化配体的金属-有机骨架材料的合成、结构及其性能研究[D]. 北京. 中国科学院大学. 2016.
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