Hydration of para-aminobenzoic acid (PABA) and its anion¡ªThe view from statistical mechanics

详细信息    查看全文

• 作者：Marina V. Fedotova ; Sergey E. Kruchinin
• 关键词：PABA ; Hydration structure ; 1D-RISM approach ; 3D-RISM approach
• 刊名：Journal of Molecular Liquids
• 出版年：2013
• 出版时间：October, 2013
• 年：2013
• 卷：186
• 期：Complete
• 页码：90-97
• 全文大小：961 K

文摘

The hydration of para-aminobenzoic acid (PABA) and its anion (PABA^?) in aqueous solution was investigated by 1D- and 3D-RISM integral equation methods. It was found that the first hydration shell of PABA and PABA^? consists of ~ 28.4 and 27.2 water molecules, respectively. The average number of water molecules close the amino group is ~ 6.6 for PABA and ~ 7 for PABA^?. The total number of H-bonds formed by the amino group is ~ 1.8 for PABA and ~ 1.9 for PABA^?. The carboxyl (COOH) group forms on average ~ 2.9 hydrogen bonds, whereas carboxylate (COO^?) has ~ 5.5. Thus, deprotonation of PABA is facilitated by increased hydration of the carboxylate moiety. For PABA and PABA^? ~ 1.2 ¦Ð-coordinated water molecules are preferably found above and below the plane of the aromatic ring at a distance of ~ 0.3 nm from the ring center with slightly stronger binding for PABA^?.