Hydrogen bond geometries and proton tautomerism of homoconjugated anions of carboxylic acids studied via H/D isotope effects on 13 C NMR chemical shifts

Jing Guo, Peter M. Tolstoy, Benjamin Koeppe, Nikolai S. Golubev, Gleb S. Denisov, Sergei N. Smirnov, Hans Heinrich Limbach

Research output

23 Citations (Scopus)

Abstract

Ten formally symmetric anionic OHO hydrogen bonded complexes, modeling Asp/Glu amino acid side chain interactions in nonaqueous environment (CDF 3 /CDF 2 Cl solution, 200-110 K) have been studied by 1 H, 2 H, and 13 C NMR spectroscopy, i.e. intermolecularly H-bonded homoconjugated anions of acetic, chloroacetic, dichloroacetic, trifluoroacetic, trimethylacetic, and isobutyric acids, and intramolecularly H-bonded hydrogen succinate, hydrogen rac-dimethylsuccinate, hydrogen maleate, and hydrogen phthalate. In particular, primary H/D isotope effects on the hydrogen bond proton signals as well as secondary H/D isotope effects on the 13 C signals of the carboxylic groups are reported and analyzed. We demonstrate that in most of the studied systems there is a degenerate proton tautomerism between O-H•••O - and O - •••H-O structures which is fast in the NMR time scale. The stronger is the proton donating ability of the acid, the shorter and more symmetric are the H-bonds in each tautomer of the homoconjugate. For the maleate and phthalate anions exhibiting intramolecular hydrogen bonds, evidence for symmetric single well potentials is obtained. We propose a correlation between H/D isotope effects on carboxylic carbon chemical shifts and the proton transfer coordinate, q 1 = 1 / 2 (r OH - r HO ), which allows us to estimate the desired OHO hydrogen bond geometries from the observed 13 C NMR parameters, taking into account the degenerate proton tautomerism.

Original languageEnglish
Pages (from-to)11180-11188
Number of pages9
JournalJournal of Physical Chemistry A
Volume116
Issue number46
DOIs
Publication statusPublished - 26 Nov 2012

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Chemical shift
Carboxylic Acids
carboxylic acids
Isotopes
isotope effect
Anions
chemical equilibrium
Protons
Hydrogen
Hydrogen bonds
Nuclear magnetic resonance
hydrogen bonds
anions
nuclear magnetic resonance
protons
Geometry
maleates
hydrogen
geometry
phthalates

Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Guo, Jing ; Tolstoy, Peter M. ; Koeppe, Benjamin ; Golubev, Nikolai S. ; Denisov, Gleb S. ; Smirnov, Sergei N. ; Limbach, Hans Heinrich. / Hydrogen bond geometries and proton tautomerism of homoconjugated anions of carboxylic acids studied via H/D isotope effects on 13 C NMR chemical shifts. In: Journal of Physical Chemistry A. 2012 ; Vol. 116, No. 46. pp. 11180-11188.
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abstract = "Ten formally symmetric anionic OHO hydrogen bonded complexes, modeling Asp/Glu amino acid side chain interactions in nonaqueous environment (CDF 3 /CDF 2 Cl solution, 200-110 K) have been studied by 1 H, 2 H, and 13 C NMR spectroscopy, i.e. intermolecularly H-bonded homoconjugated anions of acetic, chloroacetic, dichloroacetic, trifluoroacetic, trimethylacetic, and isobutyric acids, and intramolecularly H-bonded hydrogen succinate, hydrogen rac-dimethylsuccinate, hydrogen maleate, and hydrogen phthalate. In particular, primary H/D isotope effects on the hydrogen bond proton signals as well as secondary H/D isotope effects on the 13 C signals of the carboxylic groups are reported and analyzed. We demonstrate that in most of the studied systems there is a degenerate proton tautomerism between O-H•••O - and O - •••H-O structures which is fast in the NMR time scale. The stronger is the proton donating ability of the acid, the shorter and more symmetric are the H-bonds in each tautomer of the homoconjugate. For the maleate and phthalate anions exhibiting intramolecular hydrogen bonds, evidence for symmetric single well potentials is obtained. We propose a correlation between H/D isotope effects on carboxylic carbon chemical shifts and the proton transfer coordinate, q 1 = 1 / 2 (r OH - r HO ), which allows us to estimate the desired OHO hydrogen bond geometries from the observed 13 C NMR parameters, taking into account the degenerate proton tautomerism.",
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Hydrogen bond geometries and proton tautomerism of homoconjugated anions of carboxylic acids studied via H/D isotope effects on 13 C NMR chemical shifts. / Guo, Jing; Tolstoy, Peter M.; Koeppe, Benjamin; Golubev, Nikolai S.; Denisov, Gleb S.; Smirnov, Sergei N.; Limbach, Hans Heinrich.

In: Journal of Physical Chemistry A, Vol. 116, No. 46, 26.11.2012, p. 11180-11188.

Research output

TY - JOUR

T1 - Hydrogen bond geometries and proton tautomerism of homoconjugated anions of carboxylic acids studied via H/D isotope effects on 13 C NMR chemical shifts

AU - Guo, Jing

AU - Tolstoy, Peter M.

AU - Koeppe, Benjamin

AU - Golubev, Nikolai S.

AU - Denisov, Gleb S.

AU - Smirnov, Sergei N.

AU - Limbach, Hans Heinrich

PY - 2012/11/26

Y1 - 2012/11/26

N2 - Ten formally symmetric anionic OHO hydrogen bonded complexes, modeling Asp/Glu amino acid side chain interactions in nonaqueous environment (CDF 3 /CDF 2 Cl solution, 200-110 K) have been studied by 1 H, 2 H, and 13 C NMR spectroscopy, i.e. intermolecularly H-bonded homoconjugated anions of acetic, chloroacetic, dichloroacetic, trifluoroacetic, trimethylacetic, and isobutyric acids, and intramolecularly H-bonded hydrogen succinate, hydrogen rac-dimethylsuccinate, hydrogen maleate, and hydrogen phthalate. In particular, primary H/D isotope effects on the hydrogen bond proton signals as well as secondary H/D isotope effects on the 13 C signals of the carboxylic groups are reported and analyzed. We demonstrate that in most of the studied systems there is a degenerate proton tautomerism between O-H•••O - and O - •••H-O structures which is fast in the NMR time scale. The stronger is the proton donating ability of the acid, the shorter and more symmetric are the H-bonds in each tautomer of the homoconjugate. For the maleate and phthalate anions exhibiting intramolecular hydrogen bonds, evidence for symmetric single well potentials is obtained. We propose a correlation between H/D isotope effects on carboxylic carbon chemical shifts and the proton transfer coordinate, q 1 = 1 / 2 (r OH - r HO ), which allows us to estimate the desired OHO hydrogen bond geometries from the observed 13 C NMR parameters, taking into account the degenerate proton tautomerism.

AB - Ten formally symmetric anionic OHO hydrogen bonded complexes, modeling Asp/Glu amino acid side chain interactions in nonaqueous environment (CDF 3 /CDF 2 Cl solution, 200-110 K) have been studied by 1 H, 2 H, and 13 C NMR spectroscopy, i.e. intermolecularly H-bonded homoconjugated anions of acetic, chloroacetic, dichloroacetic, trifluoroacetic, trimethylacetic, and isobutyric acids, and intramolecularly H-bonded hydrogen succinate, hydrogen rac-dimethylsuccinate, hydrogen maleate, and hydrogen phthalate. In particular, primary H/D isotope effects on the hydrogen bond proton signals as well as secondary H/D isotope effects on the 13 C signals of the carboxylic groups are reported and analyzed. We demonstrate that in most of the studied systems there is a degenerate proton tautomerism between O-H•••O - and O - •••H-O structures which is fast in the NMR time scale. The stronger is the proton donating ability of the acid, the shorter and more symmetric are the H-bonds in each tautomer of the homoconjugate. For the maleate and phthalate anions exhibiting intramolecular hydrogen bonds, evidence for symmetric single well potentials is obtained. We propose a correlation between H/D isotope effects on carboxylic carbon chemical shifts and the proton transfer coordinate, q 1 = 1 / 2 (r OH - r HO ), which allows us to estimate the desired OHO hydrogen bond geometries from the observed 13 C NMR parameters, taking into account the degenerate proton tautomerism.

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U2 - 10.1021/jp304943h

DO - 10.1021/jp304943h

M3 - Article

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JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

IS - 46

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