5种氨基酸缓蚀机理的量子化学及分子动力学研究

运用密度泛函理论(DFT),在B3LYP/6-31G*水平上,计算甘氨酸、亮氨酸、天冬氨酸、精氨酸及蛋氨酸5种氨基酸类缓蚀剂的前线分子轨道能量、最高占有轨道、最低空轨道的组成及各重原子的自然电荷分布、亲核Fukui指数和亲电Fukui指数.结果表明,这5种氨基酸缓蚀性能与其分子的最高占据轨道能量EHoMo及能级差△E密切相关,EHoMo越大、△E越小,其缓蚀性能越好.其次,通过分析分子最高占有轨道、最低空轨道的组成及原子的Fukui指数,探讨此类缓蚀剂分子的反应活性位点,发现这5种氨基酸是通过N、S及羰基O原子与金属形成配位键而具有缓蚀效果.运用分子动力学模拟,获得了这5种氨基酸分子与Fe(111)晶面的结合能,结合能排列顺序由大到小依次为蛋氨酸＞精氨酸＞天冬氨酸＞亮氨酸＞甘氨酸.为判断氨基酸类缓蚀剂性能的优劣,合成新型、高效氨基酸类缓蚀剂提供了理论依据.

Quantum Chemical and Molecular Dynamics Studies on the Corrosion Inhibition Mechanism of Five Kinds of Amino Acids

Some quantum chemical parameters（front-line molecular orbital energy,composition of the highest occupied molecular orbital、the lowest unoccupied molecular orbital,natural charge of each heavy atom,nucleophilic Fukui indice,electrophilic Fukui indice） of glycin、leucine、aspartic acid、arginine and methionine were obtained at B3LYP/6-31G＊ level by means of Density Functional Theory（DFT） methods.It is found that the effects on corrosion inhibition of the five kinds of amino acids have a certain relation to the energy of the highest occupied molecular（EHOMO）and the energy gap（△E）.The larger the EHOMO and the smaller the energy gap,the better corrosion performance.Secondly,the reaction active sites were also discussed by analyzing the composition of the highest occupied molecular orbital、the lowest unoccupied molecular orbital and Fukui indice of atoms.It is found that corrosion performance of the five kinds of amino acids depends on nitrogen、sulfur and carbonyl oxygen atoms and the metal coordination bond formation.The binding energies of the five amino acid molecules with（111） crystal surface of Fe have been acquired by molecular dynamics simulation,and the orders of binding energy are as follows：methioninearginineaspartic acidleucineglycin.It provides theoretical guidance to judging the performance of amino acid corrosion inhibitors,synthesizing new,highly effective amino acid corrosion inhibitors,studying the synergistic effect of water treatment agents.