Efeitos solvatocrômicos e térmicos em compostos orgânicos contendo grupos doadores e receptores de elétrons

Abstract

In the lats decades, the studies about the spectroscopic properties of organic compounds have attracted a great interest due to the enormous possibility of the application of such systems in the identification of the physical conditions of microenviromenments, as well as in the development of electro-optical devices. In this context, this work aims to analyze the effects of solvent polarity on the emission and absorption spectra of two uorescent organic molecules, namely 2-(3-thienyl)ethyl dansylglycinate (TEDG) and 5- (dimethylamino) -N-phenylnaphthalene-1-sulfonamide, both derived from the dansil groups. This kind of compound presents danor and electron acceptor groups, exhibiting a rich phenomenology assocoated with electonic transition processes, such as local electron transition, electron transition with charge transfer and electron transitions with molecular torsion. In this study, it was investigated how the polarity of the solvent affect the spectroscopic properties of the compounds, such as the Stokes shift and variation of the dipoles moment between the fundamental and excited states. In addition, the excited state lifetime is obtained for distict values of the solvent polarity. Our results show that the enhancement in the polarity of the solvent leads to red shift emission and absorption bands, indicating tha the excited state exhibits a larger dipole moment than the ground state. This is verified by the increase in the life of the excited state as polarity of the solvent is enhanced.