| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1229241 | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2015 | 10 Pages |
•Citrate-metal complexes (Cd2+ and Pb2+) were studied by theoretical calculations, ESI MS and FTIR-ATR.•The thermodynamic stability of the metal complex was analyzed.•Theoretical calculations allowed the band assignments.
The combined use of ESI-MS, FTIR-ATR and theoretical calculations for the determination of metal-citrate (metal = Cd and Pb) structures are reported. Mass spectrometry allowed to determine the stoichiometry 1:1 and 2:1 of the complexes, corroborating the theoretical calculations. The species found in the ratio 2:1 had their molecular structures readjusted, since the deprotonation of citric acid differed from what was simulated. The calculations of thermodynamic stability (ΔH0(aq.)) for the complexes obtained by B3LYP/LANL2DZ were more exoenergetic than those found by PM6. However, for both methods, the stability of the complexes follows a trend, that is, the lowest-energy isomers in PM6 are also the most stable in B3LYP/LANL2DZ. The infrared analysis suggested that carboxyl groups are complexation sites and hydrogen bonds can help in the stability of the complexes. The vibrational frequencies in B3LYP/LANL2DZ had a good correlation with the experimental infrared results.
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