1H-NMR as a Structural and Analytical Tool of Intra- and Intermolecular Hydrogen Bonds of Phenol-Containing Natural Products and Model Compounds

Abstract

be calculated using a combination of DFT and discrete solute-solvent hydrogen bond interaction at relatively inexpensive levels of theory, namely, DFT/B3LYP/6-311++G (2d,p). Excellent correlations between experimental 1 H chemical shifts and those calculated at the ab initio level can provide a method of primary interest in order to obtain structural and conformational description of solute-solvent interactions at a molecular level. The use of the high resolution phenol hydroxyl group 1 H-NMR spectral region provides a general method for the analysis of complex plant extracts without the need for the isolation of the individual components.

Accurate ab initio calculations of O–H⋯O and O–H⋯−O proton chemical shifts: towards elucidation of the nature of the hydrogen bond and prediction of hydrogen bond distances

“…NMR spectroscopy is one of the most powerful methods for investigating hydrogen bonding interactions both in solution [11][12][13] and in the solid. NMR spectroscopy is one of the most powerful methods for investigating hydrogen bonding interactions both in solution [11][12][13] and in the solid.…”

“…It has been established that the NMR chemical shift is a very sensitive indicator of hydrogenbonding strength. Amide protons in peptide/proteins 27,28 or hydroxyl OH protons of carbohydrates [29][30][31] and phenol OH protons of natural products 13,32,33 involved in an intermolecular hydrogen bond show very strong temperature dependence (∼−12 ppb°C −1 ) whereas those involved in an intramolecular hydrogen bond have markedly lower temperature dependence (<−6 ppb°C −1 ). [16][17][18][19][20][21][22] These correlations have already been used for the characterization of strong and short hydrogen bonds in biological systems.…”

“…35 (5) Direct, across hydrogen bonds, spin-spin scalar couplings between nuclei on both sides of the hydrogen bond. 39 This technique has been used to characterize α-helix structures in polypeptides by measuring 13 CvO⋯ 1 H-15 N hydrogen bond lengths. 38 (6) REDOR experiments, which are an attractive tool for studies of hydrogen bonding in the solid.…”

“…Proton exchange rates in -OH groups can be significantly reduced in the presence of O-H⋯O intramolecular hydrogen bonds, 13,32,33 by dissolving in DMSO-d 6 or acetone-d 6 , 29 by supercooling aqueous solutions 30 or by using organic co-solvents 31 and, thus, have already been utilized in structural analysis of carbohydrates 31,46 and natural products. Proton exchange rates in -OH groups can be significantly reduced in the presence of O-H⋯O intramolecular hydrogen bonds, 13,32,33 by dissolving in DMSO-d 6 or acetone-d 6 , 29 by supercooling aqueous solutions 30 or by using organic co-solvents 31 and, thus, have already been utilized in structural analysis of carbohydrates 31,46 and natural products.…”

NMR Study of the Phenolic Component Composition of Plant Metabolomes

“…A resonance width of <10 Hz can be achieved for compound concentrations in the mM or fractions of mM range. The influences of various factors on the resonance width and position of DMSO solutions of the compounds were examined [12].…”