Highly Coplanar Very Long Oligo(alkylfuran)s: A Conjugated System with Specific Head-To-Head Defect
Highly Coplanar Very Long Oligo(alkylfuran)s: A Conjugated System with Specific Head-To-Head Defect
复制标题
DOI：
10.1021/ja411842g
复制
发表时间：
2014-02-12
影响因子：
15
通讯作者：
Bendikov, Michael
中科院分区：
文献类型：
--
作者：
Jin, Xu-Hui;Sheberla, Dennis;Bendikov, Michael
定义良好的单分散共轭低聚物具有平面骨架，不受取代基的干扰，引起了人们的广泛兴趣。在这里，我们报道了一系列对称的、异构体纯的低聚呋喃，即16-聚16F-6C(6)和相关的NF-2C(6)(n=4，6，8)。通过计算研究以及详细的光谱和X射线表征，我们首次证明呋喃主链的平面性几乎不受头对头缺陷的影响，这种缺陷会导致其寡聚或聚噻吩类化合物的相当大的扭曲。我们发现这些刚性低聚(烷基呋喃)S的性质受共轭长度的影响很大。作为迄今为止合成的最长的单分散α-低聚呋喃，16F-6C(6)被观察到是稳定的和高荧光的。对这些低聚(烷基呋喃)S氧化还原态的实验和计算研究表明，16F-6C(6)在双氧化基态下具有单重态双自由基(极化子对)特征，开壳单态(<；S-2>；=0.989)比闭壳结构稳定3.8千卡/摩尔。
Well-defined monodisperse conjugated oligomers, which have planar backbones and are free from the disturbance of substituents, attract broad interest. Herein, we report a series of symmetrical, isomerically pure oligofurans, namely, the 16-mer 16F-6C(6) together with the related nF-2C(6) (n = 4, 6, 8). Through computational studies and detailed spectroscopic and X-ray characterization, for the first time, we show that the planarity of the furan backbone is almost unaffected by the head-to-head defect which is known to cause considerable twists in its oligo- or polythiophene analogues. We present that the properties of these rigid oligo(alkylfuran)s are strongly influenced by the conjugation length. As the longest monodisperse alpha-oligofuran synthesized to date, 16F-6C(6) was observed to be stable and highly fluorescent. Experimental and computational studies of the redox states of these oligo(alkylfuran)s reveal that 16F-6C(6) has singlet biradical (polaron-pair) character in the doubly oxidized ground state; the open-shell singlet (< S-2 > = 0.989) is 3.8 kcal/mol more stable than the closed-shell dication.