本文用密度泛函理论在(RO) B3LYP/6-31G (2d,2p)水平上对山奈酚及其与水分子之间形成的氢键复合物进行结构优化,通过热力学计算研究了不同位置的酚羟基发生抽氢反应的键离解能(BDE)、质子解离反应过程的质子解离能(DPE)受分子间氢键的影响.结果表明:与H2O形成的分子间氢键会影响化合物结构,改变化合物B环与AC环的二面角,A5位酚羟基更容易发生抽氢反应和质子解离反应,此位点的BDE和DPE均明显降低,同时也降低C3位质子解离的DPE.分子间氢键的形成促使酚羟基的抽氢和质子解离反应,提高化合物抗氧化活性.%Density functional theory (DFT) calculations,based on Becke's three-parameter density functional (B3LYP) method using the 6-31G (2d,2p) basis set,were performed to evaluate the O-H bond dissociation energies (BDEs) and deprotonation energies (DPEs) of kaempferoland its hydrogen bond complex with one or two water molecules.The results showed that the intermolecular hydrogen bond with H2O would change the conformer of kaempferol,twist the dihydral angel between the B ring and AC ring.The BDE and DPE from A5-OH decreased significantly,the transfer and deprotonation of the H atom from A5-OH would be more easily compared to the single kaempferol.It was conffirmed that the water around kaempferol would accelerate the hydrogen atom or proton to dissociate from phenol hydroxyl and promote its antioxidant activity.
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