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Facile synthesis of chiral (right-handed) calcium carbonate with exceptional enantioseparation performance of dibenzoyltartaric acid

Guo, Zhongya, Wang, Jiashi, Qin, Fangfang, Shen, Wenzhong
Journal of colloid and interface science 2019
Fourier transform infrared spectroscopy, X-ray diffraction, ammonia, ammonium carbonate, aspartic acid, calcium carbonate, calcium chloride, carbon dioxide, enantiomers, maleates, moieties, nanosheets, scanning electron microscopy, stereochemistry, synergism, transmission electron microscopy, vaterite
The chiral morphology of calcium carbonate (mainly vaterite) was successfully synthesized by using CaCl2 under L-aspartic acid guiding by diffusion of in-site generation of CO2 and NH3 from (NH4)2CO3 and NH3·H2O. Its structure was characterized by XRD, SEM/TEM and FT-IR, it indicated that the helical-shaped chiral calcium carbonate was uniform in a diameter of 10-20 μm and height of 1 μm, and tortuous nanosheets with a thickness of 50 nm were evolved more abundant from center to edge in counterclockwise. The enantioseparation performance for racemic dibenzoyltartaric acid was evaluated, the chiral calcium carbonate showed certain recognition ability for L-dibenzoyltartaric acid due to its better matching with L-dibenzoyltartaric acid molecules in stereochemical structure. Chiral separation ability for dibenzoyltartaric acid could be significantly improved by dibutyl maleate modification of chiral calcium carbonate; the maximal ee values for dibenzoyltartaric acid increased from 20.62% to 62.15%. The synergism of chiral helical-shaped suprastructure, large proportion of vaterite and modification of surface by functional group resulted in the excellent enantiomer separation.