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This article is part of the supplement: 7th German Conference on Chemoinformatics: 25 CIC-Workshop

Open Access Open Badges Poster presentation

Applying the unified pH scale: absolute acidities in the gas phase and anchor points for eleven representative liquid media

Sascha K Goll1*, Daniel Himmel1, Ivo Leito2 and Ingo Krossing1

Author Affiliations

1 Institute for Inorganic and Analytical Chemistry, Freiburger Materialforschungszentrum FMF and Freiburg Institute for Advanced Studies (FRIAS), Albert-Ludwigs-Universität Freiburg, Freiburg, 79104, Germany

2 Institute of Chemistry, University of Tartu, Tartu, 50411, Estonia

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Journal of Cheminformatics 2012, 4(Suppl 1):P8  doi:10.1186/1758-2946-4-S1-P8

The electronic version of this article is the complete one and can be found online at:

Published:1 May 2012

© 2012 Goll et al; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Poster presentation

The investigations on our recently introduced unified acidity scale [1] based on the absolute chemical potential of the proton pointed out the inadequateness of the established GA scale. Earlier it was inter alia found that, when trying to correlate pKa with GA values, in several cases the correlation was broken without any sufficient explanation [2,3]. However, the GA does not take into account the pressure dependent speciation in the gas phase. In this contribution we systematically extend the theory of acidity in the gas phase from standard GAs and GBs to the real existing bulk phases [4].

Furthermore we present the rCCC (relaxed COSMO cluster-continuum) model [5], a quantum chemical solvation model for the calculation of Gibbs solvation energies of the proton with good accuracy. The rCCC values can be used to anchor individual pH scales in different solvents to our universal scale.


  1. Himmel D, Goll SK, Leito I, Krossing I: A unified pH scale for all phases.

    Angew Chem Int Ed Engl 2010, 49:6885-6888. PubMed Abstract | Publisher Full Text OpenURL

  2. Koppel IA, Koppel J, Pihl V, Leito I, Mishima M, Vlasov VM, Yagupolskii LM, Taft RW: Comparison of Brønsted acidities of neutral CH acids in gas phase and dimethyl sulfoxide.

    J Chem Soc, Perkin Trans 2 2000, 1125-1133. OpenURL

  3. Kütt A, Leito I, Kaljurand I, Sooväli L, Vlasov VM, Yagupolskii LM, Koppel IA: A comprehensive self-consistent spectrophotometric acidity scale of neutral Brønsted acids in acetonitrile.

    J Org Chem 2006, 71:2829-2838. PubMed Abstract | Publisher Full Text OpenURL

  4. Himmel D, Goll SK, Leito I, Krossing I: . to be published

  5. Himmel D, Goll SK, Leito I, Krossing I: Anchor points for the unified Brønsted acidity scale: The rCCC model for the calculation of standard Gibbs energies of proton solvation in eleven representative liquid media.

    Chem Eur J 2011, 17:5808-5826. PubMed Abstract | Publisher Full Text OpenURL