金属-多吡啶功能化碳纳米管-卟啉超分子薄膜的界面组装及其性能研究

Metal-mediated self-assembly of supramolecular ultrathin films containing metalloporphyrins has attracted much attention because of their strong thermal and chemical stability as well as structural controllability. They are potentioal molecular materials for the applications in the fields of novel opto-electronics, catalysis and for mimicking solar energy transfer. In the present project, we will firstly design and synthesize multidentate ligands of pyridine-functionalized carbon nanotubes (py-CNTs), which are used as backbones to construct coordination polymer-like multilayers. Then, we will use the molecular assembling techniques including Langmuir-Blodgett films, self-assembled monolayers and laye-by-layer assembly to construct supramolecular ultrathin films based on the metal-organic coordination reaction at interfaces. After a detailed characterization of the functionalized py-CNTs and ultrathin films, the heterogeneous catalytic reactions will be investigated. Two series of catalytic reaction will be considered, one is organic oxidation reaction of alkene derivatives and pigments, another is selective hydrogenation reaction of aromatic conjugated alkenes at room temperature. Finally, we will use the sun light as the photo-induced energy and the present heterogeneous supramolecular catalyst for the degradation of methyl orange (one example of the pigments) to clarify the potential application of the present supramolecular ultrathin films in industry. Because both the metalloporphyrins and transition metal ions were encapsulated in the matrix of metal-mediated multilayers and immobilized on the substrate surfaces, the present supramolecular heterogeneous catalysts have the advantages of high stability, good recyclability as well as the advantage of monitoring the catalytic reaction process through immersing in or withdrawing the modified substrate from the reaction solutions which provide a facile route to monitor the reaction process.

利用金属离子与多吡啶功能化碳纳米管、吡啶基卟啉之间的配位作用，组装由卟啉、金属-多吡啶基元和碳纳米管组成的三元超分子薄膜。该薄膜具有高的化学和热力学稳定性、多孔性以及结构的可控性，是一类具有良好光电、催化和模拟太阳能转换功能的超分子/纳米材料。本项目将首先设计合成多吡啶功能化的碳纳米管，然后组装由金属离子-多吡啶碳纳米管-卟啉组成的超分子薄膜。在阐明这些材料的组成、结构和光电化学性质的基础上，重点研究以固定在固体表面的超分子薄膜为异相催化剂催化氧化有机物和选择性加氢反应的条件、机理和催化效率，以及它们与超分子薄膜的组成和结构之间的关系。最后，选择稳定性和催化效率较高的含金属卟啉超分子薄膜为催化剂，探讨这类分子材料在实际应用中的可行性。由于本项目中所制备的薄膜是直接固定在固体基片的表面，所以除具有多孔材料、分子材料和纳米材料的特点外，还具有催化剂的易于分离、再生和重复利用率高的优点。

配位键具有较高的键能以及固定的配位数和特定的空间取向，因而由配位键驱动的自组装所构筑的超分子薄膜具有稳定性好、组成和分布可控、结构奇特和功能多样的特点。本项目首先通过界面重氮盐和硅烷化反应，制备了一系列的多吡啶功能化的碳纳米管和纳米SiO2。然后，以金属离子、金属配离子、四吡啶基金属卟啉、聚4-乙烯吡啶、多吡啶化碳纳米管和多吡啶化纳米SiO2等为组装单元，在固体表面和气液界面，构筑了一系列由金属配合物、金属卟啉、金属-多吡啶基元、碳纳米管和纳米SiO2等组成的多元复合纳米材料和超分子薄膜。表征了纳米材料和超分子薄膜的结构，并揭示了金属配合物和卟啉等光电活性基团的光电性质。最后，重点研究了以这些纳米材料和超分子薄膜为光敏剂和异相催化剂在光电转换和催化有机反应中的应用。.通过本项目的研究，不仅得到了一系列用于纳米/超分子体系组装的多吡啶纳米配体和具有良好光电性能的纳米复合材料和超分子薄膜，而且在对这些材料的性能和应用方面的研究中还得到了以下重要结果：(1) 碳纳米管/纳米SiO2@金属配合物纳米复合材料易于形成激基缔合物，有利于纳米配体的激发态的能量转移到与之配位的稀土金属离子，提高了稀土离子的发光效率。(2) 碳纳米管/纳米SiO2@多卟啉纳米复合材料和超分子薄膜是良好的光敏剂，可用于光电转换器件的研制、光致(紫精)变色材料/器件的研制和光催化有机染料的降解，易于回收和分离，重复使用率高。(3) 金属-氧化钛多卟啉超分子薄膜可作为H2O2的敏感剂，具有很好的稳定性和再现性。(4) 碳纳米管@金属-锰卟啉阵列纳米复合材料可作为异相助催化剂，催化芳香酚类衍生物的氧化反应，该体系同样具有易于回收、分离和重复使用率高的特点。.以纳米配体代替传统的“多齿配体”，可推动金属-有机框架多孔材料研究领域的发展，实现其孔径在纳-微米范围内的调控；纳米配体在两相界面的组装也发展了层状无机薄膜材料的制备方法。