Orientadora: Profa Dra Paula Homem de Melo / Tese (doutorado) - Universidade Federal do ABC. Programa de Pós-Graduação em Ciência e Tecnologia/Química, 2015. / In this work, it is shown the study of sensitizing molecules of phthalocyanines, porphyrins and chlorins families, with different ligands and ions complexed (Zn+2, Al+3 and Si+4), in order to assess, by computational methods, relevant properties for photodynamic therapy (PDT) application. In the first part of the work, was established an appropriate methodology to study all proposed molecules quickly and accurately. So it was chosen the Density Functional Theory and the best funcional-basis set combination found was B3LYP/LANL2DZ for optimization anf OLYP/6-31g(d) for excited states. The solvent effects were added by the solvation model IEFPCM, in order to represent the outside and inside of a lipid bilayer, respectively. In the second part of this work were obtained properties such as area, volume, dipole, frontier orbitals energy and electronic transitions of all molucules studied in order to compare them and define which complexed ions and ligands are able to modify these properties with focus on PDT. The third part studied dimers formation of some of these molecules, since this formation may affect the eletronic transitions, invalidating PDT. This study was performed with the DCACP¿s corrections applied to BLYP functional to simulate dispersion forces, responsible for the dimers formation. In the fourth part of this work, was simulated by molecular dynamics one phthalocyanine inserted into a lipid bilayer and, associated with quantum mechanics, it was possible to acess the electronic states of the molecule. These electronic states were compared with a second method for theating electronic states along a lipid bilayer with consists of a dielectric gradient that represents a membrane, in order to choose a more rapid and efficient method. The last part of this study used the same dielectric gradient to study the phosphorescence, along the lipid bilayer, showing that this method can be employed for this kind of property.