Determination of the Tautomeric Equilibria of Pyridoyl Benzoyl <beta>-Diketones in the Liquid and Solid State through the use of Deuterium Isotope Effects on 1H and 13C NMR Chemical Shifts and Spin Coupling Constants

Poul Erik Hansen, Eugeny V. Borisov, John C. Lindon

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The tautomeric equilibria for 2-pyridoyl-, 3-pyridoyl-, and 4-pyridoyl-benzoyl methane have been investigated using deuterium isotope effects on 1H and 13C chemical shifts both in the liquid and the solid state. Equilibria are established both in the liquid and the solid state. In addition, in the solution state the 2-bond and 3-bond J(1H–13C) coupling constants have been used to confirm the equilibrium positions. The isotope effects due to deuteriation at the OH position are shown to be superior to chemical shift in determination of equilibrium positions of these almost symmetrical -pyridoyl-benzoyl methanes. The assignments of the NMR spectra are supported by calculations of the chemical shifts at the DFT level. The equilibrium positions are shown to be different in the liquid and the solid state. In the liquid state the 4-pyridoyl derivative is at the B-form (C-1 is OH), whereas the 2-and 3-pyridoyl derivatives are in the A-form. In the solid state all three compounds are on the B-form. The 4-pyridoyl derivative shows unusual deuterium isotope effects in the solid, which are ascribed to a change of the crystal structure of the deuteriated compound
Original languageEnglish
JournalSpectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Volume136
Issue numberPart A
Pages (from-to)107-112
Number of pages6
ISSN1386-1425
DOIs
Publication statusPublished - 2015

Keywords

  • beta-diketones
  • solid state NMR
  • isotope effects
  • pyridines
  • tautomeric equilibria

Cite this

@article{75a329c5b7c04e5bb0ec4b3a3ebf8fbb,
title = "Determination of the Tautomeric Equilibria of Pyridoyl Benzoyl -Diketones in the Liquid and Solid State through the use of Deuterium Isotope Effects on 1H and 13C NMR Chemical Shifts and Spin Coupling Constants",
abstract = "The tautomeric equilibria for 2-pyridoyl-, 3-pyridoyl-, and 4-pyridoyl-benzoyl methane have been investigated using deuterium isotope effects on 1H and 13C chemical shifts both in the liquid and the solid state. Equilibria are established both in the liquid and the solid state. In addition, in the solution state the 2-bond and 3-bond J(1H–13C) coupling constants have been used to confirm the equilibrium positions. The isotope effects due to deuteriation at the OH position are shown to be superior to chemical shift in determination of equilibrium positions of these almost symmetrical -pyridoyl-benzoyl methanes. The assignments of the NMR spectra are supported by calculations of the chemical shifts at the DFT level. The equilibrium positions are shown to be different in the liquid and the solid state. In the liquid state the 4-pyridoyl derivative is at the B-form (C-1 is OH), whereas the 2-and 3-pyridoyl derivatives are in the A-form. In the solid state all three compounds are on the B-form. The 4-pyridoyl derivative shows unusual deuterium isotope effects in the solid, which are ascribed to a change of the crystal structure of the deuteriated compound",
keywords = "Tautomeric equilibria, solid state NMR, deuterium isotope effects, spin-spin couplings, beta-diketones, beta-diketones, solid state NMR, isotope effects, pyridines, tautomeric equilibria",
author = "Hansen, {Poul Erik} and Borisov, {Eugeny V.} and Lindon, {John C.}",
year = "2015",
doi = "10.1016/j.saa.2013.08.117",
language = "English",
volume = "136",
pages = "107--112",
journal = "Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy",
issn = "1386-1425",
publisher = "Elsevier BV",
number = "Part A",

}

TY - JOUR

T1 - Determination of the Tautomeric Equilibria of Pyridoyl Benzoyl -Diketones in the Liquid and Solid State through the use of Deuterium Isotope Effects on 1H and 13C NMR Chemical Shifts and Spin Coupling Constants

AU - Hansen, Poul Erik

AU - Borisov, Eugeny V.

AU - Lindon, John C.

PY - 2015

Y1 - 2015

N2 - The tautomeric equilibria for 2-pyridoyl-, 3-pyridoyl-, and 4-pyridoyl-benzoyl methane have been investigated using deuterium isotope effects on 1H and 13C chemical shifts both in the liquid and the solid state. Equilibria are established both in the liquid and the solid state. In addition, in the solution state the 2-bond and 3-bond J(1H–13C) coupling constants have been used to confirm the equilibrium positions. The isotope effects due to deuteriation at the OH position are shown to be superior to chemical shift in determination of equilibrium positions of these almost symmetrical -pyridoyl-benzoyl methanes. The assignments of the NMR spectra are supported by calculations of the chemical shifts at the DFT level. The equilibrium positions are shown to be different in the liquid and the solid state. In the liquid state the 4-pyridoyl derivative is at the B-form (C-1 is OH), whereas the 2-and 3-pyridoyl derivatives are in the A-form. In the solid state all three compounds are on the B-form. The 4-pyridoyl derivative shows unusual deuterium isotope effects in the solid, which are ascribed to a change of the crystal structure of the deuteriated compound

AB - The tautomeric equilibria for 2-pyridoyl-, 3-pyridoyl-, and 4-pyridoyl-benzoyl methane have been investigated using deuterium isotope effects on 1H and 13C chemical shifts both in the liquid and the solid state. Equilibria are established both in the liquid and the solid state. In addition, in the solution state the 2-bond and 3-bond J(1H–13C) coupling constants have been used to confirm the equilibrium positions. The isotope effects due to deuteriation at the OH position are shown to be superior to chemical shift in determination of equilibrium positions of these almost symmetrical -pyridoyl-benzoyl methanes. The assignments of the NMR spectra are supported by calculations of the chemical shifts at the DFT level. The equilibrium positions are shown to be different in the liquid and the solid state. In the liquid state the 4-pyridoyl derivative is at the B-form (C-1 is OH), whereas the 2-and 3-pyridoyl derivatives are in the A-form. In the solid state all three compounds are on the B-form. The 4-pyridoyl derivative shows unusual deuterium isotope effects in the solid, which are ascribed to a change of the crystal structure of the deuteriated compound

KW - Tautomeric equilibria

KW - solid state NMR

KW - deuterium isotope effects

KW - spin-spin couplings

KW - beta-diketones

KW - beta-diketones

KW - solid state NMR

KW - isotope effects

KW - pyridines

KW - tautomeric equilibria

U2 - 10.1016/j.saa.2013.08.117

DO - 10.1016/j.saa.2013.08.117

M3 - Journal article

VL - 136

SP - 107

EP - 112

JO - Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

JF - Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

SN - 1386-1425

IS - Part A

ER -