咪唑[4, 5-f] 1, 10-邻菲罗啉及其2-取代芳基衍生物的电子结构与光谱性质

分别采用B3LYP/6-31G(d)和CIS/6-31G(d)方法对咪唑4, 5-f] 1, 10-邻菲罗啉(ip)及其8种2-取代芳基衍生物的基态(S0)和单重激发态(S1)的几何构型进行了全优化, 并采用含时的度泛函理论(TD-DFT)计算了上述化合物的电子吸收和电子发射光谱. 分析了取代基对咪唑4, 5-f] 1, 10-邻菲罗啉的电子结构、前线分子轨道、电离势Ip、电子亲和势EA及电子光谱的影响. 计算结果表明, 取代基使8种取代衍生物前线分子轨道(LUMO-HOMO)能隙降低，导致其最大吸收和发射波长均发生了红移. 化合物1～8的跃迁类型均为分子内电荷转移（ICT）跃迁，且1～4和5～8的电子转移方向刚好相反. 溶剂对其电子光谱也有影响, 振子强度增大, 最大发射波长红移. 另外, 8种取代衍生物的电离势降低, 电子亲和势增大, 化合物1~4易于空穴的注入, 5~8易于电子的注入.

Electronic Structures and Spectra Properties of Imidazo [4, 5-f]-1, 10-phenanthroline and its 2-Substituted Aromatic Derivatives

The ground and excited state structures of imidazo4, 5-f]-1, 10-phenanthroline and its eight 2-substituted aromatic derivates were optimized with B3LYP/6-31G(d) and CIS/6-31G(d) methods, respectively. The absorption and emission spectra for each molecular were calculated using time-dependent density functional theory (TD-DFT) with the same basis set based on the ground and excited state geometries. The influence of the substituting group on electronic structures, frontier molecular orbitals, ionization potentials (Ips), electron affinities (EAs) and spectra properties were analyzed. The result indicated that the substituting group changed the LUMO-HOMO energy gaps of imidazo4, 5-f]-1, 10-phenanthroline, and the energy gaps are lower. As a result, the absorption and emission spectra of the eight 2-substituted aromatic derivates have a substance red shift accordingly. The transition types of the eight 2-substituted aromatic derivates are intramolecular charge transfer (ICT) transition, and the charge transfer of compound 1~4 and 5~8 are in opposite directions. The solvent has important influence for electronic spectra. The maximum emission wavelengths were red-shifted and the oscillator strength was increased. Moreover, compound 1~4 are easier for hole injection, while compound 5~8 are easier for electron injection.