高等学校化学学报

高等学校化学学报 ›› 2013, Vol. 34 ›› Issue (2): 447.doi: 10.7503/cjcu20120445

• 物理化学 • 上一篇    下一篇

D-A型共轭低聚物的电子性质及D-A比对其影响的理论研究

傅杨武, 陈明君   

  1. 重庆三峡学院化学与环境工程学院, 重庆 404100
  • 收稿日期:2012-05-04 出版日期:2013-02-10 发布日期:2013-01-21
  • 通讯作者: 傅杨武,男,博士,副教授,主要从事量子化学和功能材料研究.E-mail:fywgl@163.com E-mail:fywgl@163.com
  • 基金资助:

    国家自然科学基金(批准号: 21073144)和重庆三峡学院重点科研项目(批准号: 11ZD-10)资助.

Theoretical Investigation on the Electronic Properties of Alternating Donor-acceptor Conjugated Oligomers and the Effect of D-A Ratio on Electronic Properties

FU Yang-Wu, CHEN Ming-Jun   

  1. Department of Chemical and Environmental Engineering, Chongqing Three Gorges University, Chongqing 404100, China
  • Received:2012-05-04 Online:2013-02-10 Published:2013-01-21

PDF (PC)

被引次数

2

摘要：

以[1,2,5]噻重氮并[3,4-g]喹喔啉(TQ)为受体、 噻吩(Th)、 噻吩并[3,2-b]噻吩(TTh)和吡咯(Py)为供体, 设计了6类供体-受体(D-A)型共轭低聚物. 采用杂化的密度泛函方法(B3LYP), 研究了此6类低聚物的电子结构和性质. 电子密度拓朴分析和核独立化学位移计算表明, 随着聚合度的增加, 体系共轭程度增强, HOMO-LUMO能级差逐渐减小. 同时, 随着聚合度的增加, 低聚物电离能减小, 电子亲和势增大. 供体-受体摩尔比(D-A比)对低聚物的性质有重要影响, 提高D-A比能有效地增大分子内电荷迁移, 从而使HOMO-LUMO能级差减小. Py不仅是一个强的电子供体, 还是一个潜在的氢键供体. 在含Py结构单元的低聚物中, 由于分子内氢键的存在使其具有较大的分子内电荷迁移值. 所设计的6种基于TQ的四聚体均具有较小的HOMO-LUMO能级差(<1 eV), 使其相应的聚合物的能隙更小, 可作为潜在的性能优良的导电材料.

关键词: 共轭低聚物, 供体-受体摩尔比, 电子性质, 核独立化学位移

Abstract:

Six types of donor-acceptor conjugated oligomers were designed by choosing [1,2,5]thiadiazolo-[3,4-g]quinoxaline(TQ) as the acceptor and thiophene(Th), thieno[3,2-b]thiophene(TTh) or pyrrole(Py) as the donor unit. B3LYP method was employed to investigate the electronic structure and properties of the designed oligomers. The atoms-in-molecules(AIM) topological analysis and nuclear-independent chemical shift(NICS) results show that the conjugational degree is increased with main chain extension and thus leads to a decrease in HOMO-LUMO energy separation. In addition, the vertical ionization potential decreases and the vertical electron affinities of these oligomers increase with an increase in polymeric number. The molar ratio of donor to acceptor unit(D-A ratio) plays a very important role on the electronic properties. It is found that the intramolecular charge transfer increases and the HOMO-LUMO energy separation decreases with an increase in the ratio of donor unit. However, the effects of D-A ratio on the electronic properties become weaker as the polymer chain becomes longer. The unusually large intramolecular charge transfer caused by the intramolecular hydrogen bond reveals that pyrrole is not only a strong electron donor, but also a potential hydrogen bond donor. The theoretical results suggest the corresponding copolymers of the designed oligomers should be the good candidates for conducting materials due to the narrow HOMO-LUMO energy separation(< 1 eV).

Key words: Conjugated oligomer, Molar ratio of donor to acceptor, Electronic property, Nuclear-independent chemical shift

中图分类号: 

TrendMD: