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首页> 外文期刊>Spectrochimica acta, Part A. Molecular and biomolecular spectroscopy >Theoretical study of the changes in the vibrational characteristics arising from the hydrogen bonding between Vitamin C (L-ascorbic acid) and H2O
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Theoretical study of the changes in the vibrational characteristics arising from the hydrogen bonding between Vitamin C (L-ascorbic acid) and H2O

机译：维生素C（L-抗坏血酸）与H2O之间氢键引起的振动特性变化的理论研究

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The vibrational characteristics (vibrational frequencies, infrared intensities and Raman activities) for the hydrogen-bonded system of Vitamin C (L-ascorbic acid) with five water molecules have been predicted using ab initio SCF/6-31G(d, p) calculations and DFT (BLYP) calculations with 6-31G(d,p) and 6-31++G(d,p) basis sets. The changes in the vibrational characteristics from free monomers to a complex have been calculated. The ab initio and BLYP calculations show that the complexation between Vitamin C and five water molecules leads to large red shifts of the stretching vibrations for the monomer bonds involved in the hydrogen bonding and very strong increase in their IR intensity. The predicted frequency shifts for the stretching vibrations from Vitamin C taking part in the hydrogen bonding are up to -508 cm(-1). The magnitude of the wavenumber shifts is indicative of relatively strong OH center dot center dot center dot H hydrogen-bonded interactions. In the same time the IR intensity and Raman activity of these vibrations increase upon complexation. The IR intensity increases dramatically (up to 12 times) and Raman activity increases up to three times. The ab initio and BLYP calculations show, that the symmetric OH vibrations of water molecules are more sensitive to the complexation. The hydrogen bonding leads to very large red shifts of these vibrations and very strong increase in their IR intensity. The asymmetric OH stretching vibrations of water, free from hydrogen bonding are less sensitive to the complexation than the hydrogen-bonded symmetric O-H stretching vibrations. The increases of the IR intensities for these vibrations are lower and red shifts are negligible. (c) 2005 Elsevier B.V. All rights reserved.
机译：使用从头算SCF / 6-31G（d，p）计算并预测了具有五个水分子的维生素C（L-抗坏血酸）氢键系统的振动特性（振动频率，红外强度和拉曼活性）。使用6-31G（d，p）和6-31 ++ G（d，p）基集的DFT（BLYP）计算。计算了从游离单体到复合物的振动特性的变化。从头算和BLYP计算表明，维生素C与五个水分子之间的络合导致参与氢键结合的单体键的拉伸振动出现大的红移，并极大地提高了IR强度。参与氢键作用的维生素C的拉伸振动的预测频移最大为-508 cm（-1）。波数偏移的幅度指示相对强的OH中心点中心点中心点中心氢键合的相互作用。同时，这些振动的红外强度和拉曼活性随着络合而增加。红外强度急剧增加（最多12倍），拉曼活性增加最多3倍。从头算和BLYP计算表明，水分子的对称OH振动对络合更为敏感。氢键会导致这些振动发生非常大的红移，并使其IR强度大大增加。与氢键合的对称O-H拉伸振动相比，不含氢键的水的不对称OH拉伸振动对络合的敏感性较低。这些振动的IR强度的增加较低，并且红移可以忽略不计。 （c）2005 Elsevier B.V.保留所有权利。

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