The structures and isomerization of magnesium fluorosilylenoid H2SiFMgF were investigated by ab initio molecular orbital theory. Four equilibrium structures and three isomeric transition states were located and fully ...The structures and isomerization of magnesium fluorosilylenoid H2SiFMgF were investigated by ab initio molecular orbital theory. Four equilibrium structures and three isomeric transition states were located and fully optimized at the B3LYP/6-31G（d,p） and G3MP2B3 levels, respectively. Based on the B3LYP/6- 31G（d,p） optimized geometries, harmonic frequencies of various structures were obtained and 29Si chemical shifts were calculated. The solvent effects were investigated by means of the polarizable continuum model using THF as a solvent at B3LYP/6-31G（d,p） level. Isomerization paths for isomers were confirmed by intrinsic reaction coordinate calculations. The calculated results show that tetrahedral structure has the lowest energy and is the most stable; tetrahedral, three-membered ring, and p-complex structures are suggested to be the experimentally detectable ones; and a-complex structure has the highest energy and will not exist.展开更多
Vitamin D is a fat soluble vitamin that is foundin a variety of forms , amongwhich 1,25-（0H） 2D3 is themain active form. It not only exhibits a major physiological function to regulate the metabolism of calcium and ...Vitamin D is a fat soluble vitamin that is foundin a variety of forms , amongwhich 1,25-（0H） 2D3 is themain active form. It not only exhibits a major physiological function to regulate the metabolism of calcium and phosphorus, but also relates to the prevention and treatment of a variety of diseases such as lung diseases, cancers, diabetes, tuberculosis, lupus erythematosus, autoimmune diseases and liver damage. In this paper, the latest research progresses of the physiological function of vitamin D were summarized and discussed, aiming at providing the solid basis for utilization and application of vitamin D.展开更多
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20574043） and the Natural Science Foundation of Shandong Province （No.Z2007B02）.
文摘The structures and isomerization of magnesium fluorosilylenoid H2SiFMgF were investigated by ab initio molecular orbital theory. Four equilibrium structures and three isomeric transition states were located and fully optimized at the B3LYP/6-31G（d,p） and G3MP2B3 levels, respectively. Based on the B3LYP/6- 31G（d,p） optimized geometries, harmonic frequencies of various structures were obtained and 29Si chemical shifts were calculated. The solvent effects were investigated by means of the polarizable continuum model using THF as a solvent at B3LYP/6-31G（d,p） level. Isomerization paths for isomers were confirmed by intrinsic reaction coordinate calculations. The calculated results show that tetrahedral structure has the lowest energy and is the most stable; tetrahedral, three-membered ring, and p-complex structures are suggested to be the experimentally detectable ones; and a-complex structure has the highest energy and will not exist.
文摘Vitamin D is a fat soluble vitamin that is foundin a variety of forms , amongwhich 1,25-（0H） 2D3 is themain active form. It not only exhibits a major physiological function to regulate the metabolism of calcium and phosphorus, but also relates to the prevention and treatment of a variety of diseases such as lung diseases, cancers, diabetes, tuberculosis, lupus erythematosus, autoimmune diseases and liver damage. In this paper, the latest research progresses of the physiological function of vitamin D were summarized and discussed, aiming at providing the solid basis for utilization and application of vitamin D.
