A small shielding effect on the hydrogen atoms of chiral carbons of β-cyclodextrin （β-CD） was detected by 1H nuclear magnetic resonance, but a large environmental change of the chiral carbon atoms at high concentr...A small shielding effect on the hydrogen atoms of chiral carbons of β-cyclodextrin （β-CD） was detected by 1H nuclear magnetic resonance, but a large environmental change of the chiral carbon atoms at high concentration ratios of lithium carbonate （Li2CO3） to β-CD was observed by polarimetry in aqueous solution. These findings urged us to investigate whether different formation conditions of the molecule-ion system between Li2CO3 and β-CD in solid state were involved in different spectral performances. To answer the question, we prepared three adducts of Li2CO3 to β-CD, i.e., samples 1, 2, and 3, by magnetic stirring, solvothermal and grinding conditions, respectively. Powder X-ray diffraction and Fourier transformation infrared spectroscopy provided the information of formation of the three molecule-ion adducts. Besides, scanning electron microscope images provided different surface information of the three adducts. Further, significant spectral differences in thermal behavior of these adducts were found by thermogravimetry and derivative thermogravimetry.展开更多
基金ACKNOWLEDGMENTS This work was supported by the Innovation Foundation of Graduate Students in University of Science and Technology of China （No.KD2008020）, and the Natural Science Foundation of Anhui Province （No.090416228）.
文摘A small shielding effect on the hydrogen atoms of chiral carbons of β-cyclodextrin （β-CD） was detected by 1H nuclear magnetic resonance, but a large environmental change of the chiral carbon atoms at high concentration ratios of lithium carbonate （Li2CO3） to β-CD was observed by polarimetry in aqueous solution. These findings urged us to investigate whether different formation conditions of the molecule-ion system between Li2CO3 and β-CD in solid state were involved in different spectral performances. To answer the question, we prepared three adducts of Li2CO3 to β-CD, i.e., samples 1, 2, and 3, by magnetic stirring, solvothermal and grinding conditions, respectively. Powder X-ray diffraction and Fourier transformation infrared spectroscopy provided the information of formation of the three molecule-ion adducts. Besides, scanning electron microscope images provided different surface information of the three adducts. Further, significant spectral differences in thermal behavior of these adducts were found by thermogravimetry and derivative thermogravimetry.
