Osuna Reyes Malavé, Ortiz Rocío Ponce, Ruiz Delgado Mari Carmen, Sakamoto Youichi, Suzuki Toshiyasu, Hernandez Víctor, López Navarrete Juan T
Department of Physical Chemistry, University of Malaga, 29071-Malaga, Spain.
J Phys Chem B. 2005 Nov 10;109(44):20737-45. doi: 10.1021/jp054205b.
In this Article, we report on the synthesis and full characterization of three perfluorinated oligothiophenes, ranging in length from the trimer to the pentamer (PF-nT, with n = 3, 4, or 5). The differential pulse voltammetry (DPV) analysis of the compounds showed that they can be both oxidized and reduced (i.e., they display a dual or amphoteric electrochemical behavior), with the reduction peaks positively shifted relative to those of the corresponding unsubstituted oligothiophenes. The electrochemically determined energy gaps are in agreement with those measured from the UV-vis-NIR absorption spectra in solution. The conjugational properties have been investigated by means of FT-Raman spectroscopy, both as pure solids and as dilute solutes in CH(2)Cl(2), revealing that: (i) pi-conjugation does not still reach saturation with chain length for the longest oligomer, and (ii) conformational distortions from a nearly coplanar arrangement of the successive thiophene units upon solution are not too large. DFT and TDDFT quantum chemical calculations have been performed, at the B3LYP/6-31G level, to assess information about the optimized molecular structure, equilibrium atomic charges distribution, energies and topologies of the frontier molecular orbitals (MO) around the gap, vibrational normal modes associated with the most outstanding Raman scatterings, and vertical one-electron excitations that give rise to the main optical absorptions.
在本文中，我们报道了三种全氟代低聚噻吩（从三聚体到五聚体，即PF - nT，其中n = 3、4或5）的合成及全面表征。对这些化合物的差分脉冲伏安法（DPV）分析表明，它们既能被氧化也能被还原（即它们表现出双性或两性的电化学行为），其还原峰相对于相应的未取代低聚噻吩的还原峰发生了正向偏移。电化学测定的能隙与从溶液中的紫外 - 可见 - 近红外吸收光谱测得的能隙一致。通过傅里叶变换拉曼光谱对共轭性质进行了研究，研究对象既有纯固体形式的，也有在二氯甲烷中作为稀溶质形式的，结果表明：（i）对于最长的低聚物，π共轭仍未随着链长达到饱和；（ii）溶液中连续噻吩单元近乎共面排列的构象畸变不算太大。已在B3LYP/6 - 31G水平上进行了密度泛函理论（DFT）和含时密度泛函理论（TDDFT）量子化学计算，以评估有关优化分子结构、平衡原子电荷分布、能隙附近前沿分子轨道（MO）的能量和拓扑结构、与最显著拉曼散射相关的振动简正模式以及产生主要光吸收的垂直单电子激发等信息。
