Unraveling solvent effects on the electronic absorption spectra of TRITC fluorophore in solution: a theoretical TD-DFT/PCM study.

In this paper the equilibrium between the two ground state forms of TRITC in solvents of different polarity has been studied by means of state of the art DFT calculations using the polarizable continuum model (PCM) for including bulk solvent effects. TD-DFT/PCM calculations have been used to calculate vertical excitation energies and the UV-Vis spectra of TRITC has been interpreted in terms of the equilibrium between different forms, which is modulated by the microenvironment embedding the molecule. We show that the most intense absorption bands are sensitive to solute-solvent interactions and provide a distinctive signature of specific interactions. The good agreement with experimental data makes our approach suitable to study and monitor modifications of the chemical environment of fluorophores in different solutions as well as in interaction with biological systems and nanoparticles.