"Development of Low Energy-gap and Architecturally Well-defined pi-Conjugated Heterocyclic Highly Oligomers"

1：多功能单分子导线新型构建单元的发展单分子电子学这一新兴领域是本世纪分子材料的最后前沿。在这个项目中，我们为高性能单分子导线开发了各种类型的杂环构建块。从这些基团的选择性偶联反应中，我们合成了“结构精确控制”的杂环高低聚物（多达11个单位体系，MW-3000），其中包含各种功能单元(用于远距离和稳态电子传递的低能隙pi共轭主链，防止电荷携带的不利链间跳变的绝缘套，供体/受体位点，多阶段氧化还原位点，和鳄鱼夹连接到电极)。根据光谱性质结合MO计算结果，阐明了所得分子线的结构-性能关系。新型四端分子开关单元的设计多端分子开关单元是构建“分子计算机”的关键部件。作为一种新的候选开关单元，我设计并合成了一种新的“4端”非经典噻吩衍生物（1,3,5,7-四噻基二噻唑[3,4-b: 3', 4'-e]吡嗪）。该分子含有吡嗪-二氢吡嗪多级氧化还原中心，电子结构可通过电或电化学反应在低能隙和高能隙之间切换。基于实验和理论数据，阐明了这种新型开关系统的分子和电子特性。我们一直在开发合成方法，将各种分子线与每个末端（噻吩环的未取代的α或β位置）连接起来，以实现分子级晶体管。

1 : Development of New Building Units for Multi-functional Single Molecular WiresThe emerging field of single-molecular electronics is the final frontier of molecular materials in this century.In this project we have developed various types of heterocyclic building blocks for high-performance single molecular wires.From the selective coupling reactions of these blocks, we have synthesized "architecturally precisely-controlled" heterocyclic highly-oligomers (up to 11 unit-system, MW-3000 ) containing various functional units (a low energy-gap pi-conjugated backbone for high efficiency of long-distance and steady-state electron transport, an insulating mantle to prevent unfavorable inter-chain hopping of the charge carries, donor/acceptor sites, multi-stage redox sites, and alligator clips for the connection to an electrode).The structure-property relationships of the obtained molecular wires have been elucidated based on the spectral properties combined with the results of MO calculations.2 : Design of Novel 4-Terminal Molecular Switching UnitMulti-terminal molecular switching unit will be the key components to construct "molecular computer". As a novel candidate for switching unit, I have designed and synthesized a novel "4-terminal" non-classical thiophene derivative (1,3,5,7-tetrathienyldithieno[3,4-b : 3', 4'-e]pyrazine).This molecule contains a pyrazine-dihydropyrazine multi-stage redox center, and the electronic structure can be switchable between low and high energy-gap states by electrical or electrochemical reactions.I have elucidated the molecular and electronic features of this novel switching system based on the experimental and theoretical data.We have been developing synthetic methods to connect various molecular wires with each terminal (unsubstituted alpha or beta-positions of the thiophene rings) to realize a molecular-scale transistor.