Deprotonated Dicarboxylic Acid Homodimers: Hydrogen Bonds and Atmospheric Implications

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• 作者：Gao-Lei Hou ; Marat Valiev ; Xue-Bin Wang
• 刊名：Journal of Physical Chemistry A
• 出版年：2016
• 出版时间：April 21, 2016
• 年：2016
• 卷：120
• 期：15
• 页码：2342-2349
• 全文大小：453K
• 年卷期：0
• ISSN：1520-5215

文摘

Dicarboxylic acids represent an important class of water-soluble organic compounds found in the atmosphere. In this work we are studying properties of dicarboxylic acid homodimer complexes (HO₂C(CH₂)_nCO₂^–[HO₂C(CH₂)_nCO₂H], n = 0–12), as potentially important intermediates in aerosol formation processes. Our approach is based on experimental data from negative ion photoelectron spectra of the dimer complexes combined with updated measurements of the corresponding monomer species. These results are analyzed with quantum-mechanical calculations, which provide further information about equilibrium structures, thermochemical parameters associated with the complex formation, and evaporation rates. We find that upon formation of the dimer complexes the electron binding energies increase by 1.3–1.7 eV (30.0–39.2 kcal/mol), indicating increased stability of the dimerized complexes. Calculations indicate that these dimer complexes are characterized by the presence of strong intermolecular hydrogen bonds with high binding energies and are thermodynamically favorable to form with low evaporation rates. Comparison with the previously studied HSO₄^–[HO₂C(CH₂)₂CO₂H] complex (J. Phys. Chem. Lett. 2013, 4, 779–785) shows that HO₂C(CH₂)₂CO₂^–[HO₂C(CH₂)₂CO₂H] has very similar thermochemical properties. These results imply that dicarboxylic acids not only can contribute to the heterogeneous complexes formation involving sulfuric acid and dicarboxylic acids but also can promote the formation of homogeneous complexes by involving dicarboxylic acids themselves.