二维金属络合物纳米片的合成、结构与性能研究

Nanosheets with two-dimensional (2D) polymeric structures have recently gained much research attention. The most widely investigated examples of these nanosheets include graphene, metal oxides and metal chalcogenides which have emerged as important nanostructured materials because they exhibit novel electronic structures and physical properties as compared with the corresponding bulk samples due to the 2D confinement effect. Most of them originate from bulk-layered crystalline mother materials through exfoliation of bulk layered materials. Another type of nanosheets based on molecule-based bottom-up nanosheets is emerging and they are generally fabricated directly from atomic, ionic and molecular components. A significant advantage of the facile bottom-up synthesis is that structures can be customized through the selection of components (for example, metal ions and organic ligands). Therefore, the bottom-up approach may broaden the diversity and utility of nanosheets. Although previous reports on bottom-up nanosheets have concentrated on the fabrication and analysis of various 2D structures, no functionality has yet been demonstrated. So, it is conceived that functional 2D bottom-up metal complex nanosheets are an attractive class of nanosheets that can achieve fine control of their composition, properties, size and shape at will at the nanoscale without the need of any further treatment. This makes such functional bottom-up nanosheet as competitive as the top-down congener but such work is still at its infancy and application studies of the bottom-up nanosheets are still very rare to date. .In this proposal, the molecular design, synthesis, characterization and application studies of a new class of conjugated 2D photofunctional metal complex nanosheets will be studied. By employing different fabrication methods (viz. gas-liquid or liquid-liquid interfacial approach), both single-layer and multilayer 2D bottom-up nanosheets can be developed from a number of monomer combinations. Through judiculous ligand design, the electronic structures of these metal complex nanomaterials can be tailored to show various degrees of π-conjugation, charge carrier mobilities and tunable absorption properties, leading to functional nanosheets with controllable photoresponsive and semiconductive features. The topological structures, pore sizes, surface areas, physical and functional properties of these 2D nanomaterials will be examined as a function of the electronic nature and geometry of organic ligands and metal ions. New applications in electronics such as photoelectric conversion and field-effect transistor devices are anticipated with these new sheet-like nanomaterials. The photofunctionality associated with such bottom-up nanosheet will clearly lead to a significant expansion of the applicability of this type of 2D matters as useful and promising nanomaterials.

具有二维聚合物结构的纳米片因新颖独特的电子结构和物理特性使其受到广泛的关注，与从母体材料剥离技术制备的纳米片相比，通过“自下而上”方法制备的二维纳米片可以通过构筑成分(有机配体和金属离子)的选择以实现特定功能，从而拓宽二维纳米片的多功能性和实用性。.本项目拟设计并合成一系列基于双联吡咯啉的功能性有机/金属有机配体，采用“气-液”或“液-液”界面法将配体与不同的金属离子组合制备单层或多层二维金属络合物纳米片。通过改变配体电子结构来调控其共轭程度、电子迁移率及可调控吸收等性能，获得具有可控光响应和半导体特性的二维纳米片。在考察有机配体电子性质和几何形状和金属离子等因素基础上探讨二维纳米片的拓扑结构、孔径大小、表面积等性质，并探索其在场效应晶体管和光电领域的应用。.本项目将发展制备二维金属络合物纳米片的新方法，建立具有光电特性的二维纳米体系，为功能性二维纳米材料的可控制备提供理论依据。

二维纳米片因其新颖独特的电子结构和物理特性受到广泛关注，在众多领域表现出优异的应用潜力。本项目以“自下而上”的界面配位方法实现了大面积制备二维金属络合物纳米片，这类纳米片兼具无机和有机纳米材料的优点，可以通过配体的功能化设计和配位中心的金属选择赋予纳米片更为丰富的功能，并探讨了其在光电转换、电致变色、锂电池等领域的应用。将三联吡啶、半卟啉等典型的配位基元键连于锌-卟啉、三苯胺、四苯基苯等中心骨架，分别设计了含有三个或四个配位中心取代的有机配体，在配体溶液和金属盐水溶液形成的相界面进行配位，获得了具有特定功能的锌、铁、钴、铜等金属络合物二维纳米片，通过SEM、TEM、XPS、元素分布等技术进行了详细的表征，表明所得纳米片形貌规整、尺寸均一、厚度可控。此外，我们还进一步将这种纳米片的设计思路用于其他研究体系的前期探索，如异双金属(FePt等)系列、固-液界面制备纳米复合材料、星型铂配合物、自组装构筑有机合金等，极大地丰富了本项目的研究内容，为日后的工作延续奠定基础。前期获得的研究成果已发表论文11篇，并有部分文章正在投稿或者准备中。培养博士研究生4名，均已毕业。