Abstract: 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.

Key words: Di(thienylene vinylene), Substitution effect, Electronic structure, Excited state, Density functional theory