Ottonelli Massimo, Musso Gianfranco, Comoretto Davide, Dellepiane Giovanna
INFM-INSTM-Università di Genova, Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, I-16146 Genoa, Italy.
J Phys Chem B. 2005 Mar 31;109(12):5485-90. doi: 10.1021/jp045368n.
We discuss the effect of the interchain interactions on the electronic properties of a "dimer", named (CHD(4))(2), built from two molecules of a fully carbazolyl-substituted oligodiacetylene containing four repeating units. Each carbazolyl moiety is connected to its respective backbone through a methylene spacer, and the excitations of the neutral and doubly positively charged dimer are obtained using the CIS (configuration interaction including singles) and CEO (collective electronic oscillator) models. The separation distance between the backbones is fixed to a value that could possibly imply a very weak, if any, interchain interaction between the oligomers. In the charged dimer, where we have not been able to perform CEO calculations, it can be expected from previous results that the CIS method will behave satisfactorily. Contrary to the neutral case and surprisingly enough, the simulated photoinduced absorption (PA) spectra indicate a substituent-induced strong interaction between the oligomers, due to the very large amount of excess charge on the distorted oligomer which is spread over its carbazolyl moieties. Broadening of the lowest energy band due to the latter interaction improves the agreement between the theoretical and the experimental PA spectrum for the corresponding polymer. The through-space charge transfer directly connecting the charged with the neutral molecule could supply an efficient channel for charge transport in substituted polydiacetylenes.
我们讨论了链间相互作用对一种名为(CHD(4))(2)的“二聚体”电子性质的影响，该二聚体由两个含有四个重复单元的全咔唑基取代的低聚二乙炔分子构成。每个咔唑基部分通过一个亚甲基间隔基连接到其各自的主链上，使用CIS（含单激发的组态相互作用）和CEO（集体电子振荡器）模型获得中性和双正电荷二聚体的激发态。主链之间的分离距离固定为一个值，该值可能意味着低聚物之间存在非常弱的链间相互作用（如果有的话）。在带电二聚体中，由于我们无法进行CEO计算，根据先前的结果可以预期CIS方法将表现令人满意。与中性情况相反且令人惊讶的是，模拟的光致吸收（PA）光谱表明，由于扭曲的低聚物上分布在其咔唑基部分的过量电荷非常多，低聚物之间存在取代基诱导的强相互作用。由于后者的相互作用导致最低能带展宽，改善了相应聚合物的理论PA光谱与实验PA光谱之间的一致性。直接连接带电分子与中性分子的空间电荷转移可以为取代聚二乙炔中的电荷传输提供一个有效的通道。
