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用密度泛函理论(DFT)和含时密度泛函理论(TD。DFT)对咔唑的6种共轭基团取代衍生物的电子结构和吸收光谱性质进行了比较研究。对衍生物的基态分子结构运用B3LYP/6-31G(d)水平进行全优化,分析了电荷的分布和前线分子轨道等性质。结果表明,与母体咔唑相比,各衍生物均形成了分子内氢键,共轭体系的π键成分增大,能级差减小,激发能降低,分子的最大吸收波长向长波方向移动,即发生红移。前线分子轨道分析表明该类化合物吸收光谱主要对应分子中的HOMO→LUMO电子跃迁,且为π-π~*跃迁。共轭性基团的引入扩大了分子结构的共轭范围,增强了分子内电子的转移,改善了咔唑类化合物的光电性能。本文为新型含咔唑基团的光电功能材料的设计合成提供了理论参考。
The electronic structures and absorption spectra of 6 kinds of conjugated substituted carbazoles were compared using density functional theory (DFT) and time-dependent density functional theory (TD-FDT). The ground state molecular structure of the derivatives was fully optimized using the B3LYP / 6-31G (d) level, and the charge distribution and frontier molecular orbital properties were analyzed. The results showed that compared with the parent carbazole, all the derivatives formed intramolecular hydrogen bonds, the π bond of the conjugated system increased, the energy difference decreased, the excitation energy decreased, the maximum absorption wavelength of the molecule shifted to the long wave direction, That is red shift. Frontier molecular orbital analysis shows that these compounds mainly absorb the HOMO → LUMO electron transition in the molecule, and are π-π ~ * transitions. The introduction of conjugate groups enlarges the conjugation range of molecular structure, enhances the intramolecular electron transfer and improves the photoelectric properties of carbazole compounds. In this paper, we provide a theoretical reference for the design and synthesis of a new type of photoelectric functional material containing carbazole groups.