Modelització de la melanina

Abstract

In this work, we have an exhaustive study of different melanin oligomers as well as their properties to absorb light in the whole visible spectrum. To carry out this study, computational calculations using DFT (Density Functional Theory) and TD-DFT (Time Dependent DFT) for the excited state are used. Is used the functional CAM-B3LYP and as a calculation base 6-311G*. First, we do an introduction to explain what is melanin and which is its principal function: it’s a photo protecting molecule that protects us from the UV rays avoiding possible skin cancers. Next are the structures that will be studied in the study, discussing the most relevant aspects that have been considered. At this point, the objectives of the work are also defined. Then we find the energies of the different structures (monomers, dimers, trimers and tetramers) and in the case of trimers and tetramers, the most stable isomer is identified. Once the most stable isomer is found in each case, oxidation is performed on them and the structures are studied from oxidation state 0 to oxidation state 4. In the case of trimmers, they reach only the oxidation state 2 since these structures do not have more positions to oxidize. Next, we present an analysis of the different absorptions that each structure presents and compare the results for the structures. With these data, absorption spectra are represented to compare them with the absorption spectrum of melanin in its natural form. Moreover, HOMO and LUMO orbitals of one molecule are represented to study which behavior has the electronic structure of the oligomers. However, in this work a very detailed study of this aspect is not carried out, but it will simply be the basis for further work. Finally, the conclusions of the study are extracted and it is commented on how the study could be followed to have a more complete information on the most basic structure of melanin