甲基取代效應影響及溶劑分子效應於羧酸、胺類雨水三分子系統中氫鍵強弱之理論研究

Theoretical Study of Methylation Substitution Effect on Hydrogen Bonding Strength in the Carboxylic Acid, Amine and Water Three Molecular System

10.6623/chem.2008014

陳成(Cheng Chen)；鄭根發(Ken-Fa Cheng)；劉敏憲(Min-Hsien Liu)；洪耀勳(Yaw-Shun Hong)

甲基效應 ； 氫鍵 ； INDO程式 ； Methylation effect ； Hydrogen bonding ； INDO program

化學

66卷2期（2008 / 06 / 01）

143 - 151

繁體中文

本研究運用Gaussian 03程式中，採用密度泛函數(Density Functional Theory) B3LYP/6-311+G(2d,p)計算方法。探討甲基取代效應對羧酸、胺類與水三分子系統中氫鍵強弱之影響，發現胺上的甲基取代效應及水分子作為溶劑的結果，均顯現增強羧酸與胺類間氫鍵之趨勢。氫鍵由弱轉強促使羧酸上的氫解離，並發現氫鍵越強，羧酸上的氫之解離也較容易。同時並運用本研究室發展的INDO程式“區域化鍵分佈分析法”計算系統內之氫鍵鍵能、鍵次，輔助說明系統甲基化後的氫鍵強弱變化。

This research uses the Gaussian 03 program and adopts the density functional theory (DFT) B3LYP/6-311+G(2d,p) calculation method to explore methylation effect on the strength of hydrogen bonding among the carboxylic acid-amine-solvent medium weakly bound molecular system. It was found that the more methyl groups substitute the amine hydrogen, with existence of the water medium, the stronger for the H-bonding constructed between carboxyl and amino functional groups and the corresponding strength was stepwise increasing. The characteristic enhancement for hydrogen bonding strength leads the acidic hydrogen to dissociate easily from the carboxylic acid. The self-developed INDO program was applied for use herein. The “Localized H-bond population analysis” computed bond energy and bond order of localized Hbond, auxiliary discuss the changes of the H-bonding among research system.