磷酸与水分子间相互作用的密度泛函理论研究

Density function theory on intermolecular interactions of H_3PO_4 with H_2O

采用密度泛函理论(DFT),在PBEPBE/6-311++G**水平上,对H3PO4…H2O和H3PO4…2H2O氢键复合物的可能构型进行优化,频率验证,找到复合物的稳定结构,并分析其结构参数,计算了复合物的结合能,同时进行了振动频率分析.结果表明,水与磷酸作用的优势位置在OPOH键两端的O原子与H原子之间的分子内氢键上;磷酸和水都作为质子受体和供体,相互作用形成多元环状氢键复合物,磷酸和水的O—H伸缩振动频率都发生红移;最稳定构型复合物Trans-H3PO4…H2O的结合能为-59.57kJ.mol-1,Trans-H3PO4…2H2O的结合能为-124.70kJ.mol-1.

Based on the level of PBEPBE/6-311＋＋G＊＊,the density function theory（DFT） is used to optimize all the possible structures of H3PO4…H2O and H3PO4…2H2O hydrogen-bond complexes and to validate frequencies,as well as to analyze their parameters to find out the predominant places of interaction with water.The interaction energies have been calculated,and their vibrational frequencies have been analyzed on the same theory level.The results show that the predominated place of water interacting is the intramolecular POHO hydrogen bonds.Orthophosphoric acid and water are the providers and accepters of proton when interacting each other form two stronger relative hydrogen bonds.All the OH stretch vibration frequencies in orthophosphoric acid and water get red shifted.The bind energy of the most stable structure complex Trans-H3PO4…H2O is-59.57 kJ·mol-1,and Trans-H3PO4…2H2O is-124.70 kJ·mol-1.