Calculated bond dissociation energies and enthalpy of formation of α-amino acid radicals

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• 作者：Kabir M. Uddin ; David J. Henry ; Raymond A. Poirier…
• 刊名：Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta)
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：135
• 期：9
• 全文大小：1,598 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Theoretical and Computational Chemistry
  Inorganic Chemistry
  Organic Chemistry
  Physical Chemistry
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1432-2234
• 卷排序：135

文摘

Bond dissociation energies (BDEs), radical stabilization energies (RSEs) and the enthalpies of formation (Δ_fH°(\({\text{AA}}^{\bullet}\))) for the C_α-centered radical of 20 common α-amino acids were calculated at the G3MP2 level of theory. In addition, BDEs and Δ_fH°(\({\text{AA}}^{\bullet}\)) for the C_α-centered radicals were calculated via atomization, homolytic, isogyric and isodesmic reactions using 31 reference compounds. RSEs for the α-amino acid radicals reveal a strong captodative effect due to the resonance stabilization. Intramolecular H-bonding and steric repulsion between the side chains and –NH₂ and ‒COOH also have an effect on the stability of α-carbon-centered radicals. For the key small reference compounds investigated, the BDEs (Δ_fH°(\({\text{AA}}^{\bullet}\))) computed with isodesmic reactions were found to be quite consistent with each other in terms of mean absolute deviations (MADs) and root-mean-square deviations between 2.0 (2.6) and 3.2 (4.4) kJ mol−1 from experimental data.Keywordsα-Amino acids (α-AAs)BDEsRSEsΔ_fH°(\({\text{AA}}^{\bullet}\))G3MP2