Effect of substituents on the absorption properties of three pyridylindolizine derivatives: A DFT and TDDFT study

Ground state properties and the UV-Vis absorption spectra of three recently synthesized pyridylindolizine derivatives have been studied by using density functional theory (DFT) and its time-dependent counterpart TDDFT. Performances of the two widely used hybrid functionals, B3LYP and PBE0, and of four different basis sets have been compared. The two functionals yield absorption spectra which have very similar shapes and characteristics but the excitations calculated with PBE0 are obtained at slightly shorter wavelengths. Basis sets affect the appearances of the calculated absorption spectra only little. Independent of the solvent polarity, simulation of the solvent effects by COSMO induces only slight changes into the ground state properties compared to those calculated in the gas-phase and into the absorption spectra.