二聚(2，5-噻吩乙烯撑)基态和激发态的电子结构：桥基和芳环取代的影响

Electronic Structures of Di(thienylene vinylene) of Ground and Excited States:Vinylene-and Ring-Substitution Effects

采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)方法,在B3LYP/TZVP水平下,研究了一系列给电子基团(—NH2,—OCH3和—CH3)和吸电子基团(—CCH,—CN和—NO2)在二聚(2,5-噻吩乙烯撑)(2TV)的桥基和芳环上取代对基态和激发态电子结构的影响.结果表明,取代基的给/吸电子能力和取代位置对衍生物的几何结构以及吸收发射光谱均有重要影响,其中氨基(—NH2)和硝基(—NO2)取代对2TV电子结构的影响较为显著.此外,对于桥基和芳环取代,随着取代基吸电子能力的增强,衍生物的前线分子轨道HOMO和LUMO的能级均呈逐渐降低的趋势.

The modulation of substituents on the electronic structures of ground and excited states of di（ thienylene vinylene） （2TV） were theoretically investigated via the density function theory （DFT） and time-dependent density functional theory （TD-DFT） when a representative set of electron donating groups （ amino, methoxy, and methyl） and withdrawing groups（acetylene, cyano, and nitro） were introduced onto vinylene and thienyl moieties, respectively. Electron-donating or withdrawing capabilities and substitution position play dominant roles in the geometries and absorption and emission transition energies of 2TV derivatives. The amino- and nitro-substituent groups exert the strongest tuning effect on electronic structures among the studied systems. As the electron-withdrawing ability of substituents increases, the energy levels of the highest occupied molecular orbital （HOMO） and the lowest unoccupied molecular orbital （LUMO） of resultant derivatives exhibit a progressively reducing pattern, which is held for both thienyl and vinylene functionalizations.