Carrier Concentration Dependent Conduction in Insulator-Doped Donor/Acceptor Chain Compounds

On
the basis of the concept that the design of a mixed valence
system is a key route to create electronic conducting frameworks,
we propose a unique idea to rationally produce mixed valency in an
ionic donor/acceptor chain (i.e., D+A– chain). The doping of a redox-inert (insulator) dopant (P) into
a D+A– chain in place of neutral D enables
the creation of mixed valency A0/A– domains
between P units: P–(D+A–)nA0–P, where n is directly dependent on the dopant ratio, and charge transfer through
the P units leads to electron transport along the framework. This
hypothesis was experimentally demonstrated in an ionic DA chain synthesized
from a redox-active paddlewheel [Ru2II,II] complex
and TCNQ derivative by doping with a redox-inert [Rh2II,II] complex.

基于“混合价态体系（mixed valence system）的设计是构筑电子导电骨架（electronic conducting frameworks）的关键途径”这一核心概念，我们提出了一种可在离子型给体-受体链（ionic donor/acceptor chain，即D⁺A⁻链）中理性构筑混合价态的独特思路。具体而言，以氧化还原惰性（redox-inert）的绝缘体型掺杂剂（dopant，P）取代中性给体（D）掺入D⁺A⁻链，可在掺杂剂单元之间形成A⁰/A⁻混合价域，所得结构为P–(D⁺A⁻)ₙA⁰–P，其中n值直接由掺杂剂比例决定；电荷经由掺杂剂单元传输，可实现骨架沿链方向的电子传导。该假说已通过实验得到验证：以氧化还原惰性的[Rh₂Ⅱ,Ⅱ]配合物作为掺杂剂，由氧化还原活性桨轮状[Ru₂Ⅱ,Ⅱ]配合物与TCNQ衍生物合成的离子型给体-受体链，可成功实现上述混合价态构筑与电子传导。