Density Functional Theory Calculations of the Molecular Force Field of L-Ascorbic Acid, Vitamin C
Density Functional Theory Calculations of the Molecular Force Field of L-Ascorbic Acid, Vitamin C
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DOI：
10.1021/jp912251g
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发表时间：
2010-04-15
影响因子：
2.9
通讯作者：
Brandan, Silvia A.
中科院分区：
文献类型：
--
作者：
Bichara, Laura C.;Lanus, Hernan E.;Brandan, Silvia A.
对L抗坏血酸进行了研究，并用红外光谱对其进行了表征。密度泛函理论(DFT)方法与Pop le基组相结合，从理论上确定了该化合物在气相中的三个稳定构象，而在实验观察到的固相中平均只存在两个较稳定的构象。在B3LYP/6-31G*和B3LYP/6-311++G**水平上计算了两种结构优化构型的简谐振动波数。将密度泛函理论计算与Pulay的尺度量子力学力场方法相结合，对化合物固体和水溶液的振动光谱进行了完整的归属，以使理论波数与实验值相吻合。用这种方法，完成了L-抗坏血酸红外光谱中所有观察到的谱带的完整归属。自然键轨道研究揭示了这三种结构的电子离域特征，并用Bader原子分子理论分析了相应的电子电荷密度的拓扑性质。
We have studied L-ascorbic acid and characterized it by infrared spectroscopy in solid and aqueous solution phases. The density functional theory (DFT) method together with Pop le's basis set show that three stable molecules for the compound have been theoretically determined in the gas phase, and that an average of only two more stable conformations are present in the solid phase, as it was experimentally observed. The harmonic vibrational wavenumbers for the optimized geometries of both structures were calculated at B3LYP/6-31G*and B3LYP/6-311++G** levels at the proximity of the isolated molecule. For a complete assignment of the vibrational spectra in the compound solid and aqueous solution phases, DFT calculations were combined with Pulay's scaled quantum mechanics force field methodology in order to fit the theoretical wavenumber values to the experimental ones. In this way, a complete assignment of all the observed bands in the infrared spectrum for L-ascorbic acid was performed. The natural bond orbital study reveals the characteristics of the electronic delocalization of the three structures while the corresponding topological properties of electronic charge density are analyzed by employing Bader's atoms-in-molecules theory.