【作者】 佘能芳；

【导师】 吴安心；

【作者基本信息】 华中师范大学 ， 有机化学， 2008， 博士

【摘要】 荧光传感器以其灵敏度高、使用方便等优点而备受人们的关注，近年来得到了迅速的发展。而基于主客体作用机制设计、制备的各种荧光传感器则是化学传感器研究的一个重要方面。这类荧光传感器的特点是由具有空腔结构的主体单元作为外来物种的接受体，主体分子和客体分子通过特异性相互作用形成主客体复合物，从而表现出对客体分子高度识别的能力，待检测物种与主体分子的作用改变了主体分子所连接发光体的微环境，引起其发光行为发生变化。因而通过检测发光体发光特性的变化就可以实现对客体分子的选择性识别和测定。本论文研究的中心工作是在传统的甘脲类主体化合物上引入荧光基团，设计和合成出一系列新型的、基于甘脲的、拥有不同立体空腔的荧光主体化合物，并研究它们对各种金属阳离子、有机或无机阴离子以及酚类中性客体分子的识别和荧光传感性能。此外，晶体工程学是分子工程学的一个重要组成部分，它涉及分子或化学基团在晶体中的组装行为、晶体的设计及结构与性能的控制。我们所合成的甘脲衍生物是一类具有特殊拓扑结构的三维立体分子，是开展分子组装研究的非常有用的模块。本文另一方面的工作是研究两个系列的两单元甘脲衍生物作为不同类型的组装合成子在自组装过程中表达出的特殊结构形态。具体内容如下：1．近年来基于一些经典的超分子主体化合物的荧光传感器工作得到了长足发展。我们按不同主体和不同的作用机制对相关的研究进展做了较详细的综述，并由此提出了本论文的设想和研究思路。2．将芳香乙炔通过Sonogashira偶联反应引入到含溴的三单元甘脲分子夹上，设计合成了十个新颖的三单元荧光分子夹。对其光学性能的研究发现，该类荧光分子夹对Fe³⁺具有高选择性响应。它们与Fe³⁺形成的复合物体系呈现荧光猝灭效应，表现出对Fe³⁺的“on-off”开关行为，而碱金属离子、碱土金属离子及Ag⁺、Hg²⁺、Cu²⁺、Ni²⁺、Cd²⁺、Zn²⁺、Mn²⁺、pb²⁺、Cr³⁺和Co²⁺等十九种离子对荧光分子夹的荧光光谱不产生明显的影响。另一方面，这类荧光分子夹还对4-硝基苯酚分子表现出较高的选择性响应，它们可以通过氢键作用和π…π作用与4-硝基苯酚形成包结物使其荧光猝灭，而对对苯二酚等其它八种酚类衍生物均没有产生响应。通过¹H NMR，IR，Job Plot等一系列手段对形成的包结物进行了表征，并初步推断了其相互作用的可能机理。3．设计并合成了八种基于二乙酯基甘脲的新型两单元荧光化合物，即含两个酰胺基团为识别位点的阴离子受体，并在乙腈溶剂中研究了它们对阴离子的选择性识别作用。结果表明F^-、OAc^-和H₂PO₄^-能使该类荧光分子的荧光发射产生猝灭，荧光峰位置基本不变。但猝灭程度很小，灵敏度较低。4．拓扑选择性地合成出具有更大空腔的甘脲二聚桥联的四单元分子夹——C-shaped产物，在此基础上将荧光基团引入到C-shaped的产物上，得到四单元甘脲荧光分子夹，进而研究它对金属离子及酚类客体的识别作用。结果表明C-shaped的四单元荧光分子夹也对Fe³⁺和4-硝基苯酚表现出较高的选择性，且都表现为荧光猝灭的形式。5．设计、合成了八个含不同芳香炔基官能团的甘脲两单元建筑模块，得到了其中五个化合物的晶体结构并对其进行了研究，从中发现了一个奇异的、通过氢键和C-H…π作用协同组装而成，由甘脲衍生物四聚体构筑的分子碗状的特形晶体堆积态。6．依据组装再组装的串级组装策略，我们设计、合成了一类含吡啶官能团的两单元甘脲衍生物，并成功预测和构筑了一类新颖的分子网格堆积态。综上所述，整个论文工作取得了系列阶段性成果，共合成42个新化合物，测定了23个化合物的晶体结构，为该研究方向的进一步拓展积累了较为丰富的经验与实验数据。更多还原

【Abstract】 Fluorescent chemosensors have attracted much attention and got a rapid development over the years for their high sensitivity and simplicity. The design and synthesis of fluorescent chemosensor based on host-guest interaction has been an important area of chemosensors. The characteristic of this kind of fluorescence sensor is that the hosts including cavity interact with the guests and formed host-guest complex by the interactions between hosts and detected substrates, which lead to the change of luminescent micro-environment and result in the variety of luminescent capability. Therefore, the selective recognition and detection of guest species can be monitored through recording the changed light signals of the illuminant. Based on the glycoluril, we designed and synthesized a series of novel fluorescent chemsensors including different three-dimensional cavities by introducing the fluorophores into the receptor. Their recognition and sensing abilities toward various metal ions, anions and neutral guests were studied. In addition, the crystal engineering is an important section of the molecular engineering, which involves the assembly behavior of molecules or chemical groups in crystal, the design of crystal and the control of the structure and performance. The synthesized molecules with specific topological three-dimensional structure could be used as excellent building blocks in the studies of molecular assembly. Hence, the other emphasis of this thesis focuses primarily on studying the special crystal structure modality of two series of two-unit glycoluril-based derivatives in the course of assembly.The main contents are shown as following:1. In recent years, the fluorescent chemosensors based on the classical traditional supramolecular host molecules have gained the rapid development. A detailed review was carried out about their research progress with a classification according to different hosts and different photoinduced process. We put forward our design ideas and research topics based on the above review.2. Ten fluorescent molecular clips based on glycoluril were designed and synthesized by using Sonogashira coupling reaction to covalently attach terminal aryl alkynes to the aromatic sidewalls of bromized molecular clip and buildπ-systems that function as fluorophore moieties. Their photophysical characteristics were studied. The results demonstrated that these fluorescent molecular clips exhibited very strong fluorescence responses to Fe³⁺ and had remarkably high selectivity to Fe³⁺ over other metal ions including alkali metals, alkaline-earth metals and Ag⁺, Hg²⁺, Cu²⁺, Ni²⁺, Cd²⁺, Zn²⁺, Mn²⁺, Pb²⁺, Cr³⁺ ,Co⁺ et al. On the other hand, these fluorescent molecular clips had also an excellent selective recognition for 4-nitrophenol. They bound 4-nitrophenol through hydrogen bonds andπ-πstacking interactions and had no affinity with other eight hydroxybenzene derivatives such as hydroquinone. The complexes were characterized through ¹H NMR, IR and Job-plot analyses and the possible mechanism was proposed.3. Eight novel fluorescent anion receptors of two unit glycoluril derivatives with double ureidyl N-H used as the binding sites were designed and synthesized. Their recognition behaviors toward various anions in CH₃CN solvent were studied. Results indicated anion receptors were capable of selectively binding F^-, OAc^- and H₂PO₄^- over other anions. However, the changes of fluorescence emission were unobvious with low sensitivity.4. Methylene-bridged glycoluril C-shaped dimmers----four unit molecular clips with larger cavity were topologically synthesized. The fluorophores were attached to C-shaped dimmer and fluorescent four unit molecular clip was obtained. Also, its photophysical properties for recognitions of metal ions and hydroxybenzene derivatives were investigated. It was found that the chemosensor could selectively recognize Fe³⁺ and 4-nitrophenol and displayed fluorescence quenching.5. Eight building blocks in which different aryl alkynes moieties were linked to two unit glycoluril derivatives were synthesized and five systematic structures of single crystal were obtained. We found a novel tetrameric molecular bowl crystal packing morphology formed by hydrogen bond and C-H…πinteractions.6. Based on the tandem assembly strategy of assembly and biassembly, we designed and synthesized a series of two unit glycoluril derivatives bearing pyridine moieties and successfully predicted and constructed a novel type of molecular grid network.In summary, the stage results were obtained in this thesis. We obtained forty-two new compounds and twenty-three systematic structures of single crystal which afforded abundant experiment data for further expanding.更多还原