环境诱导下构型自调的四硫富瓦烯衍生物：设计合成及可控超分子组装研究

Organic functional materials are based on the assembly of organic molecules via intermolecular interactions. Therefore, the gateway for the development of organic functional materials is to design and synthesize organic molecules having unique features on both electronic and crystallographic aspects. In the present proposal, we aim at the design, synthesis, and supramolecular assembly diversity of functional organic molecules possessing conformation self-modulation ability induced by circumstance variation. The target molecules are aryl-substituted/fused tetrathiafulvalene (TTF) derivatives, for which the aryls and TTF framework are connected via sulfur atom bridge. The key characters of these molecules are (1) extention of pi-conjugation result from aryls, and (2) enhancement of molecular internal freedom caused by the rotation/vibration of aryls around two C-S bonds. The target molecules will be synthesized through the copper-catalyzed C-S coupling reaction between aryl iodides and (TBA)2[Zn(DMIT)2], and by successive phosphate-mediated coupling reaction. The supramolecular assembly of the resulting TTF derivatives and other functional components, such as fullerene, transition metals, rare earth metals, and heteropoly acid (HPA) will be carried out. The driving forces for supramolecular assembly are hydrogen-bond, pi-pi interaction, charge-transfer, and coordination between TTF derivatives and counter components. Especially, the rotation/vibration of aryls around two C-S bonds would make the peripheral aryls and central TTF core together form a bowl-like cavity under certain conditions, which is capable to encapsulate guest molecules having appropriate size and symmetry, for example, fullerene and HPA. The target materials are conducting inclusion complex with fullerene, conducting/magnetic inclusion complexes with HPA, conducting/magetic metal-organic framework (MOF), one-dimensional magnets of transition metal, and co-existence of conduction (TTF stacks) and magnetism (transition metal sheet). Futher investigation is directed to the fabrication of molecular electronic devices based on the above supramolecular materials.

有机功能材料籍由有机分子通过分子间作用组装而成，因此合成具有特殊本征性能及组装功能的有机分子是有机功能材料研究的基础及创新点。本项目以四硫富瓦烯（TTF）为母体，在其外围以硫原子为桥联，引入具有不同电子效应、对称性及组装功能基团的芳香环。目标分子的独特性在于扩展了体系的pi-共轭结构；而且芳基围绕C-S键的旋转/振动自由度，使得分子的构型能够受物理或化学环境之诱导而自发调整，譬如呈碗状构型。利用分子间pi-pi作用、配位作用、电荷转移以及芳基围绕TTF骨架旋转/振动所形成的分子内禀空腔，通过电化学结晶及多组份扩散等方法实现TTF衍生物的混合结晶，及其与过渡金属、富勒烯、杂多酸等功能组分的可控超分子组装和功能熔合。以期得到具有特殊组装结构（包络复合物、金属-有机框架结构、过渡金属链）和性能(导电、磁性、吸附、催化)的有机功能材料。在阐明材料的构效关系之基础上，拓展组装材料在分子器件中的应用。

有机功能材料籍由有机分子通过分子间作用组装而成，因此合成具有特殊本征性能及组装功能的有机分子是有机功能材料研究的基础及创新点。在本项目中，我们沿着“分子设计合成分子构效关系研究可控超分子组装组装材料的性能及构效关系研究”这一思路，设计了新型的有机功能砌块单元，并针对其结构特点开展了可控超分子组装及组装材料的性能研究。新型砌块单元为“硫原子桥联芳基取代稠合的四硫富瓦烯（简称 Ar-S-TTF）”，它们的分子构型能够受物理或化学环境之诱导而自发调整。截至项目结题，我们以“Cu-催化的C-S键偶联反应”为关键步骤，实现了Ar-S-TTF的高效合成并建立了相应的化合物库（总计超过200余种新化合物）。运用物理有机化学等手段研究了Ar-S-TTF的构效关系，阐明了它们具有环境响应性组装特征，能够根据客体分子的尺寸、形状、对称性、氧化还原能力等因素的变化而调整自身的空间构型和价态来形成不同的组装结构。基于Ar-S-TTF的结构特点和本征电化学性能，实现了它们与富勒烯、磷钼酸的包络复合型超分子组装，与电子受体（CuBr2、I2、F4TCNQ）之间的电荷转移型超分子组装，与过渡金属离子配位组装，制备了一系列结构及功能各异的超分子组装材料。探索并发掘了超分子组装材料性能，它们在有机太阳能电池、磁性气体吸附、光诱导自旋态捕截、双极性半导体材料、化学掺杂自旋态调控等方面具有潜在应用价值。在本项目执行期内，共发表SCI论文13篇，包括 Angew. Chem. Int. Ed., Chem. Eur. J., J. Mater. Chem. C, CrystEngComm, Chem. Commun., Beilstein J. Org. Chem 等。参与本项目的研究生，5人获得博士学位，3人获得硕士学位。项目负责人邵向锋教授于2015年获得国家自然科学基金委优秀青年科学基金。