基于新型大π共轭有机配体的二维MOFs的制备及其电学性质研究

Two-dimensional graphite-like metal-organic frameworks (MOFs) are able to achieve high charge transport property coexisting with porosity and high surface area, thus have great application potential in novel optoelectronic devices. The charge transport properties of 2D MOFs are closely related to their organic ligands. However, the organic ligands of reported 2D MOFs are limited to benzene or triphenylene derivatives. The key scientific issue about how structures, properties and charge transport performances of 2D MOFs were affected by conjugated organic ligands has never been reported yet. In this project, we propose a series of non-triphenylene conjugated ligands with large π systems to systematically investigate the influences of organic ligands on the structures and electrical properties (carrier concentration, type and mobility) of 2D MOFs. The conjugation systems, side chains and coordination atoms of organic ligands would be studied in detail. This project would focus on exploring and establishing a controllable way to modulate the crystal structures, energy bands and charge transport performances of 2D MOFs through organic ligands engineering. The research results of this project are expected to promote the understanding of the charge transfer mechanism in 2D MOFs. Based on these fundamental studies, the success of the proposed research is expected to result in new organic ligands engineering strategies for 2D MOFs with high charge transport performance, and to promote the development and application of electronic devices based on 2D MOFs.

二维类石墨结构金属有机框架材料(MOFs)在保持高孔隙率的同时可实现高电荷传导率，因而在新型光电器件中具有巨大的应用潜力。二维MOFs的电荷传输性能与其配体性质密切相关，然而目前已报道二维MOFs材料皆是以苯或者三亚苯衍生物为有机配体。共轭有机配体结构与性质对二维MOFs材料的结构、性质及电荷传输影响这一关键科学问题尚未有深入研究的相关报道。本项目拟设计并合成一系列非三亚苯结构的大π共轭有机配体分子，系统研究配体分子的共轭体系、侧基及配位原子对二维MOFs材料的结构及电学性质（载流子浓度、类型及迁移率）影响，探索并构建通过有机配体实现二维MOFs材料晶体结构、能带及电荷传输性能的可控调节方法。本项目研究结果有望促进对二维MOFs电荷传输机理的理解，为更高电荷传输性能二维MOFs材料的设计提供新思路，为基于二维MOFS材料电子器件的发展做出贡献。

共轭有机配体分子对二维MOFs 材料最终结构和电学性质起着至关重要的作用。本项目以具有三亚萘及三亚喹喔啉骨架结构的大π共轭有机配体分子为合成目标，探索基于该类大π共轭有机配体分子的的二维MOFs材料的制备方法、结构表征及电学性质研究。在项目执行期内，完成了以下工作：（1）新型大π共轭有机配体分子的设计、合成及表征；（2）自组装二维金属有机框架材料的制备及表征；（3）基于场效应晶体管的二维金属有机框架材料的电学性质研究;此外，在基于所合成的大π共轭有机配体分子基础上，我们进一步探索了(4) 基于三亚喹喔啉大π配体分子共价有机骨架(COF)材料的制备及表征;(5)基于大π配体分子氢键有机框架化合物(HOF)材料的制备及表征。研究表明大π共轭有机配体分子随其芳香体系的扩大，分子间π-π作用相应增强，有利于其所制备MOFs或COFs产物结晶性的提高，但分子π-π作用增强的同时会极大降低配体分子本身的溶解度，对其后续应用带来不利影响。本项目所合成的系列具有大π共轭结构的配体分子，因其通常具有良好的共平面性及众多的反应位点，特别适合于进一步制备二维的共价有机骨架及氢键有机框架化合物，本项目为共价有机骨架及氢键有机框架化合物的制备和研究提供更多素材和寄出。本项目研究中发现利用羧基与胺基的酸碱反应，并借助于凝胶晶体生长法，可成功制备出基于氢键的二维有机单晶材料，更进一步，通过加热或者微波反应，可以使单晶中的胺基及羧基继续反应，从而有望通过该途径制备出具有单晶结构的二维共价有机化合物。上述研究，为后续基于单晶结构的二维共价有机化合物的制备工作开拓了新的研究思路。