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.