Optical properties of wine pigments: theoretical guidelines with new methodological perspectives

Wine pigmentation results from the complex chemistry of anthocyanins. Their flavylium cation form is stabilized either by chemical transformation occurring during wine aging (e.g., pyranoanthocyanin formation), or by the formation of non-covalent complexes with (phenolic) copigments. Molecular modeling (quantum mechanics and molecular dynamics) is more and more adapted to understand wine chemistry and pigmentation. The constant developments of theoretical methodologies might get non-specialists easily lost. This manuscript is a review of the theoretical studies dedicated to the field of wine pigments, showing conformational analysis, energetics of the various forms, pigment/copigment (non-)covalent association, and charge transfer excited states. QM/MM calculations are newly performed here, which improve solvent description. The conclusion is a comprehensive guideline for an accurate prediction of light absorption by wine pigments and all related supramolecular processes.P.T. thanks INSERM and the ‘Conseil Régional du Limousin’. Financial support from the Czech Science Foundation (P208/12/G016), the Operational Program Research and Development for Innovations—European Regional Development Fund (project CZ.1.05/2.1.00/03.0058 of the Ministry of Education, Youth and Sports of the Czech Republic), the Barrande Project (No. 7AMB12FR026) and the Operational Program Education for Competitiveness—European Social Fund (project CZ.1.07/2.3.00/20.0058 of the Ministry of Education, Youth and Sports of the Czech Republic) is also gratefully acknowledged. The work at IMDEA was supported by the Spanish Ministerio de Economía y Competitividad (MINECO; project CTQ2011-27317). M.L. thanks the Swedish e-Science Research Center (SeRC) for financial support