中文摘要：

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.

英文摘要：

Six types of donor-acceptor conjugated oligomers were designed by choosing thiadiazolo-quinoxaline（TQ） as the acceptor and thiophene（Th）,thienothiophene（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）.