DFT Theoretical Study On The Intermolecular Interaction Of Phosphoric Acid And Water

The intermolecular interaction is very important in the areas such as chemistry, biology and so on. The experiment and theory study on the series of effect is attracting more and more attention of chemists, biologists and scientists of material area. In the research of the interaction between molecules, hydrogen bond is the earliest one that people studied, and the researching process of it also stand for the understanding process of the intermolecular interaction on certain side. To study the further realization, the interaction between molecules in terms of theory can explain some profounder level problems such as biological phenomena, process of evolution even life science to a certain degree.Phosphoric acid is the highest valence oxyacid of phosphorus, including orthophosphoric acid(.H₃PO₄), pyrophosphoric acid (H₄P₂O₇) ,triphosphoric acid (H₅P₃O₁₀)and metaphosphoric acid [(HPO₃)_n]. Phosphoric acid is one of the common inorganic oxyacid and belong to middling intensity acid. It is widely used in technology and agriculture. Especially, phosphoric acid can form ester with many organic compounds, and phosphate ester and its acid anhydride dominate the biosphere. DNA and RNA as the heredity matters, they belong to phosphoric di-ester that is their bridge linkage group. Adenosine triphosphate ATP is composed of adenine, D-ribose and three orthophosphoric acid groups. AMP and ADP separately comprise one and two orthophosphoric acid groups. When ATP hydrolysis its phosphate chain parts and then forms one or two orthophosphate groups. Although phosphoric acid is big differences between DNA, RNA and ATP on chemical character, phosphoric acid is a fragment of their molecules, and it is also a prototype of understanding them.Water is the source of life. Water plays an important role in structure stabilization of biologic high molecules and running its biologic function. According to research the interaction between phosphoric acid and water, we may provide some important information about the interaction on DNA with water, ATP hydrolysis and the "high energy" phosphate linkage P-O-P.This thesis employed Gaussian03 program on the level of PBEPBE/6-311++G** to optimize all the possible structures of H₃PO₄…H₂O,H₃PO₄…2H₂O,H₄P₂O₇…H₂O and H₅P₃O₁₀…H₂O Hydrogen-Bond complexes and to validate frequencies, as well as to...