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

虽然π共轭分子将小到中等大小已被广泛研究，那些具有较大的π系统仍有很多有待探索和研究，可能是由于在合成，处理和结构表征的难度增加。本计画的主要目的是设计、合成并阐明新型的延伸π-系统的结构-性质关系。这两年取得了以下成果。(1)继我们第一次合成的几个triquinarenemethane二离子，我们已经成功地合成hexacyanotriquinarenemethane二阴离子1，一个稳定的和高度四极性的物质，和triquinarenemethane二离子在终端具有芳香族离子部分。这些双离子在可见光到近红外区域显示出强的吸收。(2)对于1的合成，我们已经开发了一种通用的合成子，其广泛适用于各种二氰基醌二甲烷的合成。作为第一个例子，我们合成并研究了一些双氰基二芳基醌二甲烷2，其偶极性很大程度上改变了对位取代基的电子性质。(3)考虑到硼原子的吸电子性质，我们设计并合成了空间位阻保护的硼醌二甲烷3和中心含硼的三喹芳烃甲烷类似物。化合物3显示出明显的溶剂化变色性，并正在进行进一步的研究。(4)我们还合成了基于六取代苯骨架的树枝状大分子型六合物4，四（2-噻吩基）醌二甲烷5，和一种新的二苯醌衍生物6。化合物4是第一个碳氢六方环化的例子，醌二甲烷5显示出良好的两性氧化还原性质，而扩展的醌6经历了醌和双自由基形式之间的高度可逆的光化学和热异构化，涉及构象变化。这个属性6表示一个开关函数。

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.