Estudo teórico e eletroquímico da molécula 3,6- di(tiofen-2-il)pirrolo[3,4-c]pirrol-1,4(2H,5H)-diona

Abstract

Among the most versatile materials in the area of organic and electrochemical electronics, conductive polymers have a prominent place, mainly due to their semiconductor properties and possible applications such materials can have, such as electrochromic devices, photovoltaic cells, field effect transistors, among others. For the development of these materials, however, it is necessary to study, firstly, the behavior of the respective monomers that will give rise to them, in order to make the proper adjustment of its chemical reactivity, against the possible reactions that will be used in its polymerization, as well as the adjustment of the energy levels of the border orbitals of such materials, seeking to obtain increasingly efficient optoelectronic devices. Based on these considerations, the theoretical and electrochemical study of the molecule 3,6-bis (thiophen-2-yl) -2,5 bis(alkyl)pyrrolo [3,4-c] pyrrole-1,4-(2H,5H)-dione (DPP2T), seeking to understand, in a qualitative way, the way in which its electronic structure influences its chemical reactivity against radical polymerization reactions, as well as to study other physicochemical properties such as its reduction potentials, its ionization potential and the excitation energy of the HOMO-LUMO transition. Through such a study, it has been found that, depending on the substituent which is attached at the 5-positions of the thiophene rings of the DPP2T molecule, there is a stabilization, to a greater or lesser degree, of the radical cation generated by the electrochemical oxidation of diketopyrrolopyrrolederived molecules. From the construction of the radial distribution function of the mass centers of the solvent molecules (chloroform) in relation to the center of mass of the molecule DPP2T, the radius of the first sphere of solvation of this molecule last is around 12 Å. As regards the HOMO energy estimation method of organic molecules through the electrochemical technique of cyclic voltammetry, it is noted that the inclusion of diffusers in the base 6-31G (d, p) gives a better approximation between the electrochemically obtained value and the value obtained by the DFTB3LYP method.