The effective condensation of organic π-electron systems in crystal

通过在新的π电子体系1-芳基-2，5-二(2-噻吩基)吡咯中引入一个三氰基乙烯基得到的化合物(1)，得到了具有类金金属光泽的稳定晶体。我们从金属光泽是基于有机π-电子系统在晶体中的有效凝聚的基本观点对这一现象进行了研究。1)金属光泽起源的基础理论研究：从母体1-aryl-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrroles和1-aryl-2，5-bis(5-tricyanoethenyl-2-thienyl)-pyrroles，出发，合成了以芳环或呋喃环取代噻吩环的π及其衍生物。这些衍生物被发现形成具有金色或绿色金属光泽的晶体。详细研究了金属颜色和晶体结构之间的关系，以表明金属颜色的种类归因于π-系统彼此相互作用的方式。2)目前π-系统在纳米材料中的应用：发现在母体π-系统中引入长烷基链后，在保持π-系统凝聚的情况下人为地改变了π-分子在晶体中的排列，这对金属光泽的出现是重要的，以开发一种新型的纳米材料。3)在电子导电材料中的应用：已经表明：(1)化合物(1)在与电子受体掺杂的情况下表现出导电性能。在本研究中，在其末端引入甲氧基或二苯氨基等给电子基提高了电导率。

The compound (1) that is made by introducing a tricyanoethenyl group into a novel π-electron system, 1-aryl-2,5-di(2-thienyl)pyrrole, gave stable crystals with gold-like metallic luster. We investigated this phenomenon from a point of basic view that the metallic luster is based on the effective condensation of organic π-electron systems in crystal. We also made its practical application and, as a result, the following results have been gained.1)Basic and Theoretical Investigation of the Origin of the Metallic Luster : Starting from the parent π-systems, 1-aryl-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrroles and 1-aryl-2,5-bis(5-tricyanoethenyl-2-thienyl)-pyrroles, their derivative that have an arene ring or a furan ring instead of the thiophene were synthesized. These derivatives were found to form crystals with gold-like or greenish metallic luster. The relationship between metallic color and crystal structure was investigated in detail to show that the kind of metallic color is attributable to how the π-systems interact to each other.2)Utilization of the Present π-System for Nanoscopic Materials : It was found that introduction of a long alkyl chain into the parent π-system changes artificially the arrangement of the π-molecules in the crystal under keeping the condensation of the π-systems, which is important to the emergence of metallic luster, to develop a novel nanoscopic materials.3)The Application to Electron-conducting Materials : It had been shown that the compounds (1) exhibit electric conductivity under doping with an electron acceptor. In the present research, the introduction of an electron-donating group such as methoxyl or diphenylamino group at their terminal thiophene increases electric conductivity.