【作者】 丁慧敏；

【导师】 汪成；

【作者基本信息】 武汉大学 ， 无机化学， 2018， 博士

【摘要】 晶态有机多孔材料包括有机分子笼(OMCs)以及共价有机框架化合物(COFs),它们大多采用动态共价化学(DCC)构筑,不仅具有质轻、比表面高、稳定性好等优点而且还具有结构可设计性,功能可调控性等特点,已在气体存储与分离、催化、传感以及储能等显示出巨大的应用价值。然而,OMCs及COFs中还有许多问题亟待解决。对于OMCs,首先要解决其产率低、提纯难的问题。其次,从应用角度来看,需攻克OMCs的定向功能化以及大尺寸空腔构筑的难题。对于COFs,构筑基元的扩充、功能单元的定向引入以及新应用领域的开发是该领域的重要挑战。基于此,本文通过一类DCC反应即席夫碱反应,可控设计、合成一系列单分散的有机分子笼,再到二维、三维的框架材料。从结构设计入手解决了 OMCs及COFs的高效合成以及定向功能化的问题,并探究了它们的结构与性质之间的关系,开发了有机多孔材料的新用途。主要的研究成果如下:1.通过模板合成法与席夫碱反应的结合高效构筑了卟啉有机分子笼。仅在室温静置的条件下即可定量合成卟啉分子笼,解决了分子笼合成步骤复杂、产率低、分离提纯困难等问题。并且通过扩散法得到了目标分子笼的单晶,进一步解析后,对其结构进行了研究。2.研究发现分子笼中心的模板大小决定了其空腔大小,通过控制模板的尺寸,同时调节反应物之间的匹配程度,构筑了一系列不同大小的卟啉有机分子笼,实现对分子笼大小的定向调控。为进一步研究其在分子反应器、主客体化学方面的研究奠定了基础。3.采用自下而上的设计理念解决OMCs功能基团的引入问题。通过前体设计,制备含缺电子基团的1,3,5-三嗪前体,利用席夫碱反应一步简单高效地合成出了[4 + 6]构型三嗪基分子笼。经单晶结构解析及气体吸附测试对其结构及多孔性进行了研究,并探究了其在二氧化碳选择性吸附分离方面的应用。4.OMCs在应用过程中存在着许多局限性,比如化学/热稳定性不高、回收利用困难等。而COFs在弥补这些缺陷的同时还拓展了更为广阔的应用前景。如COFs作为光电活性材料的研究越来越受到研究者的重视,针对光电活性COFs中存在的问题,一是光电基团的扩充,二是如何利用活性单元的调控来提升电导率,本文通过席夫碱反应制备了含四硫富瓦烯(TTF)结构单元的二维COFs(TTF-COF)。并考察了 TTF-COF的结构和电化学性能,通过客体分子掺杂的方式调控骨架中TTF的价态从而改善材料导电性。5.三维COFs的高效构筑及功能化是COFs领域中亟待突破的研究方向之一。通过合理的前体设计,采用席夫碱反应制备了第一个基于AIEgen的三维共价有机框架化合物(3D-TPE-COF)。并考察了 3D-TPE-COF的结构及光学性能。基于其独特的荧光性能及较高的量子产率,进一步探究了其作为荧光活性物质在白色发光二极管(WLED)中的潜在应用。更多还原

【Abstract】 Crystalline porous organic materials consist of covalent organic molecular cages(OMCs)and covalent organic frameworks(COFs).Most of OMCs and COFs are constructed via dynamic covalent chemistry(DCC).Either of them possesses the advantages of light weight,high surface area,good stability,designable structure and controllable functionality which shows promising applications in gas storage and separation,catalysis,sensing,energy storage etc.However,there are still lots of problems in OMCs and COFs that remains to be solved.For OMCs,the first target is to solve the problem of low yield and complicated purification.Secondly,it is necessary to overcome the difficulties of functionalization and the construction of OMCs with large cavities for further application.For COFs,the expansion of the building blocks,the incorporation of functional groups,and the exploration of new application are highly desirable in this field.Based on this,we designed and prepared a series of monodisperse OMCs,and then to two-dimensional,three-dimensional frameworks via Schiff-base reaction.Though the elaborate structural design,we achieved the efficient synthesis and oriented functionalization of OMCs,and further explored the relationship between their structure and properties.The main research results are as follows:1.Via template-directed imine condensation reactions,we have constructed covalent porphyrinic cages with different spacer lengths,in which the cage compounds have been conveniently synthesized in quantitative yields at room temperature.The single crystals of the target molecular cages were obtained by diffusion method and further analysis of the structures was conducted through X-ray single crystal diffraction.This solves a large number of the problems in the construction of OMCs such as complex synthetic steps,low yields,and difficulties in purification.2.We found that the size of the template in the center determines the cavity size of OMCs.Then,by selectively choosing the templates and adjusting the length of diamine spacers,another two cages with larger sizes could be formed in one-step with quantitative conversion.From the successful preparation of OMCs,we believe that the template-directed imine condensation reaction can be used generally to synthesize OMCs of varying sizes.Once the template was removed,we may obtain porous cages with varying cavity sizes,which may enable us to further investigate their applications for encapsulating different guest molecules.3.Though bottom-up strategy,we introduce an electron-deficient functional group into OMCs and synthesized the triazine-based[4 + 6]cage in one-pot reaction.The crystal structure and permanent porosity of the triazine-based cage has been investigated by X-ray diffraction and nitrogen sorption measurement,respectively.Moreover,the cage compound exhibits high selective adsorption of CO2 over N2 due to the abundant imine groups and suitable cavity size.4.There are many deficiencies for OMCs in the practical application,such as low chemical/thermal stability and inconvenient recycling.While the structural uniqueness of COFs has brought these new materials great potential for advanced applications.For example,COFs as photoelectrically active materials have attracted extensive attention.One of the key aspects in electroactive COFs yet to be developed is the expansion of optoelectronic groups and how to increase the conductivity.We have synthesized an electroactive COF containing the TTF monomer for the first time.Moreover,we clearly demonstrate that the well-defined TTF-COF shows high thermal stability and permanent porosity,and it is amenable to doping with iodine,which could improve the conductivity of TTF-COF bulk samples.This novel system provides a new way to prepare well-ordered conjugated TTF materials and may find applications in various fields from electronic devices to energy storage.5.The efficient construction and functionalization of three-dimensional COFs is a key research direction in the field of COFs.We report the design and synthesis of an AIEgen-based 3D covalent organic framework(3D-TPE-COF)for the first time.Interestingly,3D-TPE-COF emits yellow fluorescence upon excitation,with a photoluminescence quantum yield of 20%.Moreover,by simply coating 3D-TPE-COF onto a commercial blue light-emitting diode(LED),a prototype white LED(WLED)was fabricated.更多还原