Lacroix Jean Christophe, Chane-Ching Kathleen Isabelle, Maquère Fabrice, Maurel François
ITODYS, Université Paris 7-Denis Diderot, CNRS UMR 7086, 1 rue Guy de la Brosse, 75005 Paris, France.
J Am Chem Soc. 2006 Jun 7;128(22):7264-76. doi: 10.1021/ja060390a.
Organic mixed valence compounds consisting of bisdiarylamino charge-bearing units with an oligothiophene bridge and oligothiophene radical cations have been compared using molecular modeling. The study has been performed with oligomers of 1 to 22 thiophene units. These two series of molecules have several properties in common, and intramolecular Single Electron Transfer (SET) in both series can be described within the same theoretical framework. Conducting oligomer radical cations and slightly doped conducting polymers appear as special cases of the vast ensemble of organic mixed valence compounds. Short oligomers are class III, whereas longer oligomers and conducting polymers are class II. Therefore, doped conducting polymers cannot be correctly modeled using oligomers with a short conjugation length. Experimental evidence extracted from the literature confirms these findings. Single electron transfer theories can thus be used when studying interchain and intrachain electron transfer in slightly doped conducting polymers and in materials consisting of short oligomers. This makes it possible to extract from the UV-vis-near-IR spectra the electron-transfer constant rate along or between the pi-conjugated chain. The main differences among inorganic, organic, and conducting oligomer or polymer mixed valence compounds lies in the H(ab) and lambda values associated with these different series. Inorganic mixed valence compounds have small H(ab) and lambda values; organic mixed valence compounds have large H(ab) and lambda values, whereas conducting oligomers and polymers have large H(ab) but small lambda values. This induces charge delocalization to occur for systems larger than those of inorganic and nitrogen-centered organic mixed valence compounds.
已使用分子建模对由带有双二芳基氨基电荷单元、以低聚噻吩为桥连的有机混合价化合物和低聚噻吩自由基阳离子进行了比较。该研究针对具有1至22个噻吩单元的低聚物展开。这两类分子具有若干共同性质，并且两类分子中的分子内单电子转移（SET）都可在同一理论框架内进行描述。导电低聚物自由基阳离子和轻度掺杂的导电聚合物表现为大量有机混合价化合物中的特殊情况。短链低聚物属于III类，而长链低聚物和导电聚合物属于II类。因此，不能使用具有短共轭长度的低聚物对掺杂导电聚合物进行正确建模。从文献中提取的实验证据证实了这些发现。因此，在研究轻度掺杂导电聚合物和由短链低聚物组成的材料中的链间和链内电子转移时，可以使用单电子转移理论。这使得从紫外-可见-近红外光谱中提取沿π共轭链或在π共轭链之间的电子转移恒定速率成为可能。无机、有机以及导电低聚物或聚合物混合价化合物之间的主要差异在于与这些不同系列相关的H(ab)和λ值。无机混合价化合物的H(ab)和λ值较小；有机混合价化合物的H(ab)和λ值较大，而导电低聚物和聚合物的H(ab)较大但λ值较小。这导致对于比无机和以氮为中心的有机混合价化合物更大的体系会发生电荷离域。
