8
614 J. Phys. Chem. B, Vol. 114, No. 26, 2010
Rauwald et al.
accurately.72 With improvements in algorithms and computer
performance, powerful calculation schemes have arisen for the
estimation of solvation free energies. Different competing
strategies have been suggested, such as solvent reaction fields
using a self-consistent field approach to the Schr o¨ dinger
equation,73 group additivity methods, and also an implementa-
it is expected to be of general interest to biochemical research
areas, such as protein-ligand and drug-receptor design.
Acknowledgment. Mr. Sean Ohlinger from Wavefunction
is gratefully acknowledged for helpful discussions and providing
us with the new SM8 solvation implementation of Spartan’08.
The authors also thank the EPSRC, the Walters-Kundert Trust,
the Royal Society, and the Fondation Wiener-Anspach for
funding. F.B. thanks the German Academic Exchange Service
(DAAD) and Studienstiftung des Deutschen Volkes for financial
support.
74
7
5
tion of the Poisson-Boltzmann theory.
In this work, the SM8 quantum mechanical continuum
7
6,77
solvation model,
developed by Cramer and Truhlar, was
chosen for its low computational cost, facile implementation,
and good performance in “blind” studies with mean errors of
78
2
.3 kJ/mol. In addition, its wide applicability to various solvent
Supporting Information Available: Figures containing ITC
and ESI-MS data of various H·G complexes, and a plot
illustrating the effect of concentration on the extent of complex
formation. This material is available free of charge via the
Internet at http://pubs.acs.org/.
combinations allows for the extension of our ESI-MS method
to other solvent environments. However, it should be noted that
these computational methods need to be applied cautiously
toward molecules that substantially differ from the parametriza-
tion set.72 Indeed, close inspection of the reported training set
for SM877 revealed that no ortho-substituted aromatic com-
pounds capable of intramolecular hydrogen bond formation were
included; hence, the calculated ∆Gsolv’s in these instances are
questionable. Furthermore, the lack of experimental values for
highly polar compounds may be reflected in lower quality
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