MM/QM study: Interactions of copper(II) and mercury(II) with food dyes in aqueous solutions

Aim

In this work we studied four azo dyes which are proposed for synthetic colorants in foods applications and named L₁: Sunset Yellow, E110, L₂: Tartrazin, E102, L₃: Amaranth, E123, L₄: Red Ponceau 4R, E124. In addition, electron density analysis has been carried out to highlight the possible strengths of interaction of these four azo dyes with metal ions.

Materials and methods

Density Functional Theory (DFT) was utilized, using the B3LYP functional and the 6-31G(d) basis set. This level of calculation was used to find the optimized molecular structure and to predict the molecular orbitals energies, dipole moment, Fukui function values ${f^{-}}_k$, locals nucleophilicity indexes N_k and the chemical reactivity parameters that arise from Conceptual DFT. Also, the steric energies values from the four complexes were calculated with the EMO program using MM2 method.

Results

Complexes forms with mercury are easier to form and more stable than copper. These show that the mercury intoxication is faster than the copper, knowing that mercury is toxic even with low dose. For that, the men who carry amalgams, we advise may be avoid to eat food and drugs which contain azo dyes because there exists a high trend between these azo dyes and the metal ions which released by the amalgams.