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Recent interest in the absorption and photo-luminescence properties of a molecule with an envisioned optoelectronic use, such as TPD (N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine), prompted us to apply Density Functional Theory (DFT) and Time-Dependent DFT methods to obtain theoretical results in agreement with experimental findings. Based on these benchmark results, we tackled in a further step the study of a set of molecules derived from the triphenylamine moiety, trying thus to relate their structures with their expected behavior in optical devices. Therefore, we analyzed several key properties for it, like the Stokes shift (important for laser applications), or their absorption and emission spectra which, together with the energies of frontier molecular orbitals, help to determine their optical behavior.

The competition between Na+ and K+ with a protein for water was investigated by using Density Functional Theory (DFT) calculations. The optimized potential energy curves have been made in the DFT, together with balanced basis sets of split valence Def2-SV(P). Initially, calculations were done in order to know the organization of the hydration shell of the sodium and potassium ions, when up to sixteen molecules of water are added. The results indicate the structure and stability of these cations with water clusters. Then, this knowledge was used for the analysis of the hydrated protein when potassium or sodium cations approach them, showing that cation has a dehydration process more favorable energetically, and indicating for which cation, potassium or sodium is the competition with the protein for water more favorable.