Through-space electrostatic field effect on protonation energies OF α,ω-diamino acids

Klára Ösapay, Gábor Náray-Szabó

Research output: Article

4 Citations (Scopus)


Theoretical gas-phase protonation energies, Ep, of the zwitterionic forms of 2,3-diaminopropionic acid, 2,4-diaminobutyric acid, ornithine and lysine are compared. It is shown that the charged carboxylate or ammonium groups strongly influence the value of Ep even if they are located far from the protonated nitrogen atom. Comparing Ep with the minimum electrostatic potentials, calculated from fully transferable bond fragments, it is demonstrated that the above substituents influence protonation energies by a through-space electrostatic, rather than by a through-bond inductive, mechanism. A simple equation is given to estimate substituent effects. By analyzing pKa values, measured in aqueous solution, the primary importance of hydration is stressed.

Original languageEnglish
Pages (from-to)57-62
Number of pages6
JournalJournal of Molecular Structure
Issue numberC
Publication statusPublished - 1983

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry
  • Inorganic Chemistry

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