Protonation and electronic structure of 2,6-dichlorophenolindophenolate during reduction. A theoretical study including explicit solvent

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• 作者：Michal Malček ; Lukáš Bučinský ; Zuzana Barbieriková…
• 关键词：2 ; 6 ; Dichlorophenolindophenolate ; Electronic structure ; Molecular dynamics ; Proton transfer ; QTAIM ; Solvent effects
• 刊名：Journal of Molecular Modeling
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：22
• 期：10
• 全文大小：1,598 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Computer Applications in Chemistry
  Biomedicine
  Molecular Medicine
  Health Informatics and Administration
  Life Sciences
  Computer Application in Life Sciences
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：0948-5023
• 卷排序：22

文摘

Protonation in the two-electron/two-proton reduction processes of 2,6-dichlorophenolindophenolate (DCIP) is investigated combining density functional theory (DFT) and molecular dynamics (MD) methods. DCIP (anion), DCIP•– (radical anion), and DCIP2− (dianion) are considered, including the electronic structure analysis from the prospective of quantum theory of atoms and molecules (QTAIM). It is shown that oxygen on the indophenolate moiety and nitrogen are the first and/or the second proton acceptor sites and their energetic order depends on the total charge of the system. MD simulations of differently charged species interacting with the solvent molecules have been performed for methanol, water, and oxonium cation (H₃O+). Methanol and water molecules are found to form only hydrogen bonds with the solute irrespective of its charge. The calculated pK_a values show that the imino group of DCIPH− is a weaker acid than water. While in the case of DCIP (and DCIP•–) plus oxonium cation, proton transfer from the solvent to the solute was evidenced for both aforementioned acceptor sites. In addition, MD simulations of bulks containing 15 and 43 molecules of water around the DCIP molecule have been performed, revealing the formation of 2–4 hydrogen bonds.