Spectroscopic studies of Copper I and II complexes by DFT calculations.

Mechanistic studies have helped on elucidating the mode of action of metal complexes in cancer treatment.1 Study the cell uptake and intracellular distribution of luminescent bioactive complexes2, in order to identify the main targets is one of the most applied methods. Therefore, in this work we performed DFT calculations to predict some important thermodynamical and spectroscopical information of three different ligands and their copper (I)/(II) complexes. Compounds structures were planned to achieve adequate spectroscopical characteristics, possible luminescent properties and interact to DNA by intercalation due the presence of a planar aromatic organic system (Figure 1 A). Optimization data showed that Cu(II) complexes have lower distortion of square planar geometry than Cu(I) analogues. Results demonstrated that the oxidation number determine the kind of transitions, we observed a MLCT band to the Cu(I) compounds and a band LMCT to Cu (II) complexes. Cu(II) complexes have better absorption in lower energies region (around 570 nm) (Figure 1B) compared to the Cu(I) compounds (around 420 nm). Then, Cu(II) compounds are more suitable to reach our objective, since this region is not affected by biomolecules absorptions and planar structure can help non-covalent interactions in the biological field. The most promising compound was the [Cu(DPOQ)2]2+ (DPOQ = dipyrido[1,2,5]oxadiazolo[3,4b]quinoxaline) due the more rigid structure, smaller distortion angles and higher absorption wavelengths. Experimental studies will be performed to investigate the luminescent and biological properties of this complex.