Toward hydrophobic carminic acid derivatives and their inclusion in polyacrylates.

Carminic acid, a natural hydrophilic dye extensively used in food and cosmetic industries, is converted in hydrophobic dyes by acetylation or pivaloylation. These derivatives are successfully used as biocolorants for polyacrylate objects. Spectroscopic properties of the carminic acid derivatives in DMSO and in polybutylacrylate are studied by means of Photoluminescence and Time Resolved Photoluminescence decays, revealing an hypsochromic effect due to presence of bulky substituents as the acetyl or pivaloyl groups. Molecular Mechanics and Density Functional Theory (DFT) calculations confirm the disruption of planarity between the sugar ring and the anthraquinoid system determined by the esterification.