Abstract

Aluminum (III) and Magnesium (II) interactions with the aromatic containing aminoacid chains are studied using the B3LYP density functional. Bader and the NBO analyses have been performed over the optimized structures in order to shed light on the effect of the metal on the aromatic rings. We began by studying the interactions between the metal cations and benzene. Then a methyl was added to represent more accurately the phenylalanine functional group. We have also studied, in a similar way, the functional groups of the tyrosine and tryptophan aminoacids. The strongest bond is 447 kcal/mol, which occurs between the Al(III) and the indole. For magnesium, the strongest bond is 151 kcal/mol for the methyl-indole complex. As in the complexes of previous sections, the addition of the methyl leads stronger binding complexes , and this effect is significantly larger for aluminum than for magnesium. The NBO and Bader analyses revealed that the aromaticity of the carbon rings remains after interaction with magnesium. However, when the ring interacts with aluminum, aromaticity is lost, even though certain delocalization is kept.