Effect of headgroup chirality in nanoassemblies. 2. Thermal behavior of vitamin C-based surfactants.
l-Ascorbic and d-isoascorbic acids are epimers, and their alkanoyl-esters are surfactant-like in water. These ascorbic acid derivatives retain the same stereogenic configurations of the parent molecules. That circumstance strongly affects their physicochemical properties, both in the solid and in the dispersed states. The thermal behavior of 6-O-l-ascorbyl-dodecanoate (l-ASC12), of 6-O-d-isoascorbyl-dodecanoate (d-ASC12), and of their mixtures was investigated through DSC, XRD, and FTIR experiments. The results indicate that the mixtures of the two epimers produce two eutectics and a 1:1 molecular compound, both in the pure phase and in the coagel state. From the phase diagram data, the activity coefficients of the different species and the main excess thermodynamic functions can be calculated. The results provide insight into the effects of stereochemistry on their intermolecular interactions.
Lo Nostro
Pierandrea
P
Department of Chemistry and CSGI, University of Florence, 50019 Sesto Fiorentino, Firenze, Italy.
Ambrosi
Moira
M
Ninham
Barry W
BW
Baglioni
Piero
P
D001205:Ascorbic Acid / Q000138:chemical synthesis / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology; D013055:Spectrophotometry, Infrared; D013501:Surface-Active Agents / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
D013501:Surface-Active Agents; D014867:Water; D001205:Ascorbic Acid