Synthesis and Properties of Novel Extended pi-Conjugated Systems with Good Functionality

尽管小到中等大小的pi共轭分子已经得到了广泛的研究，但那些具有更大的pi-体系的分子仍然有很多需要探索和研究的地方，这可能是因为合成、操作和结构表征的难度越来越大。这个项目的主要目的是设计、合成和阐明新型扩展的pi-体系的结构-性质关系。在这两年中，我们获得了以下结果：(1)首次合成了几种三喹烷双离子，并成功地合成了一种稳定的高四极物质六氰基三喹甲烷二阴离子1，以及末端带有芳香族离子基团的三喹烷双离子。这些二离子在可见光到近红外区表现出很强的吸收。(2)针对1，4-二氰基喹烷的合成，我们开发了一种通用性较强的合成子，可广泛应用于合成多种二氰基喹二甲烷。作为第一个例子，我们合成并研究了一些偶极随对位取代基电子性质变化很大的二氰基二芳基喹二甲烷2。(3)考虑到硼原子的吸电子性质，我们设计合成了空间保护的硼基二甲烷3和以硼原子为中心的三喹芳烷类似物。化合物3表现出明显的溶致变色性，进一步的研究正在进行中。(4)我们还合成了基于六取代苯骨架4、四(2-噻吩基)喹二甲烷5的树枝状大分子，以及一种新的二苯并苯醌衍生物6。化合物4是氢杂环己烷的第一个例子，喹二甲烷5表现出良好的两性氧化还原性能，扩展的醌6在苯醌和二自由基间进行了高度可逆的光化学和热异构化反应，涉及构象变化。该属性6表示开关函数。

Although pi-conjugated molecules will small to medium size have been studied extensively, those with larger pi-systems have remained much to be explored and studied probably owing to increasing difficulties in the synthesis, handling, and structural characterization. The primary purpose of this project is to design, synthesize, and elucidate the structure-property relationship of novel extended pi-systems. The following results have been obtained in these two years.(1) Following to our first synthesis of several triquinarenemethane di-ions, we have succeeded in the synthesis of hexacyanotriquinarenemethane dianion 1, a stable and highly tetrapolar substance, and triquinarenemethane di-ions having aromatic ion moieties at the terminals. These di-ions show strong absorptions in the visible to near-infrared region.(2) For the synthesis of 1 we have developed a versatile synthon which is widely applicable to the synthesis of a variety of dicyanoquinodimethanes. As the first examples we synthesized and studied a number of dicyanodiarylquinodimethanes 2 whose dipolarity largely changes by the electronic nature of para-substituents.(3) Taking electron-withdrawing nature of boron atom into account, we designed and synthesized sterically protected boraquinodimethanes 3 and a triquinarenemethane analogue having a boron atom at the center. Compounds 3 show appreciable solvatoshromism and further studies are undergoing.(4) We have also synthesized dendrimer-type hexacations based on hexa-substituted benzene skeleton 4, tetrakis (2-thienyl) quinodimethanes 5, and a new dibenzoterquinone derivative 6. Compounds 4 are the first example of hydrocabon haxaxation, quinodimethanes 5 show good amphoteric redox properties, and the extended quinone 6 undergoes a highly reversible photochemical and thermal isomerization between quinone and diradical form involving conformational change. This property of 6 represents a switch function.