ABORDAGENS DFT PARA ESPECTROS DE ABSORÇÃO UV-VIS: EXPLORANDO SEMELHANÇAS E DIFERENÇAS EM COMPOSTOS ORGÂNICO E DE COORDENAÇÃO

DFT APPROACHES TO UV-VIS ABSORPTION SPECTRA: EXPLORING SIMILARITIES AND DIFFERENCES IN ORGANIC AND COORDINATION COMPOUNDS. Ultraviolet-visible (UV-Vis) absorption spectroscopy is widely used in chemistry to analyze electronic structures and molecular properties. Computational chemistry, particularly density functional theory (DFT) and time-dependent DFT (TD-DFT), offers valuable tools to support and complement experimental studies. This study evaluates various functionals and basis sets to describe the ground-state geometry and UV-Vis spectra of trans-azobenzene (trans-AB) and 3-ferrocenyltrans-azobenzene (3-FCAB). The results indicate that M06-L/def2-TZVP describes trans-AB, while ωB97X-D3(BJ) is more suitable for the ground-state properties of 3-FCAB, with O3LYP performing best for excited-state properties. The Pauling point concept emerges as a guiding principle, highlighting the balance between computational cost and accuracy. Our findings suggest that gasphase optimized geometries can yield accurate TD-DFT spectra, avoiding unnecessary complexity from solvation effects. The study reinforces system- and property-dependent nature of DFT, emphasizing the need for testing different density functionals. It provides a guide and recommends functionals as starting points for treating similar organic and coordination compounds.