2-取代芳基菲并咪唑类化合物的电子结构和光谱性质的理论研究

Theoretical studies on electronic structures and spectra properties of 2-substituted aromatic phenanthroimidazoles

运用密度泛函理论,在B3LYP/6-31G(d)水平上对菲并咪唑(PI)及其8种2-取代芳基衍生物的结构进行了全优化,探讨了取代基对分子结构、电离势(I_P)、电子亲和势(E_A)、电荷转移、前线分子轨道能量和电子吸收光谱等方面的影响.采用含时的度泛函理论(TD-DFT)计算了各分子的气相及液相的电子吸收光谱,计算结果与实验值十分接近.并用GaussSum2.1程序模拟吸收光谱和态密度(DOS)图,结果表明,芳基4′-位上取代基对菲并咪唑(PI)和苯环的骨架结构没有很大的扰动,但它们重新调整了菲并咪唑环和苯环中原子电荷分布,前线分子轨道(LUMO)-HOMO)能隙降低,导致8种取代的化合物的吸收波长均发生了红移.

The structure of Phenanthroimidazole and its eight 2-Substituted Aromatic derivates were optimized at B3LYP/6-31G（d） level. The Molecular structure, ionization potential（Ip）, electron affinities （EA）, molecular charge transfer, energies of frontier molecular orbitals and the electronic absorption spectra have been investigated. The absorption spectra for each molecular were calculated in gas and solvent respectively by the time-dependent density functional theory TD-B3LYP with the 6-31G （d） basis set and compared with the experimental data. The calculated results of absorption spectra are in good agreement with the experimental data. At the same time, the absorption spectra and the density of states （DOS） have been studied using GaussSum2. 1 program. The result indicated that these substitution groups did not disturb the structure of Phenanthroimidazole and benzene extremely. Meanwhile, they re-adjusted the contribution of atomic charges and then have changed the LUMO-HOMO energy gaps of Phenanthroimidazole derivates. As a result, the absorption spectra of the eight 2-Substituted Aromatic derivates have a substance red shift accordingly.