Impact of intramolecular hydrogen bonding of gallic acid conformers on chemical shift through NMR spectroscopy

Backler, Frederick; Wang, Feng

doi:10.1016/j.jmgm.2019.107486

Cited by 6 publications

(15 citation statements)

References 24 publications

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“…For this reason, computational XPS and NMR calculations can be employed to study conformers and intramolecular hydrogen bonding, which helps the determination of the conformer distributions. 65,66 In the NMR study of gallic acid conformers, CMS calculated C-NMR chemical shifts of theoretically possible conformers indicate that the C-NMR chemical shifts can be employed to study intramolecular hydrogen bonding of conformers, as indicated in Fig. 11.…”

Section: Photoelectron Spectroscopy and Electron Momentum Spectroscopymentioning

confidence: 99%

“…66 6)) given in the C-NMR measurement, 67 is untrue. 66 This is due to the fact that NMR spectroscopy associates with slower time scale than rotations (flipping about the axis in Fig. 11).…”

Section: Photoelectron Spectroscopy and Electron Momentum Spectroscopymentioning

confidence: 99%

“…74 As environmentsensitive fluorophores, quinazoline derivatives are a special class of chromophores that could allow for deeper understanding of biological binding and function of candidate EGFR tyrosine Fig. 11 Comparison of calculated 13 C NMR spectra of gallic acid conformers 66 with NMR experiment in dimethyl sulfoxide (DMSO) solvent. 67 Note that the vertical dashed line on the structure on the right represents the molecular axis of the gallic acid.…”

Section: Photoelectron Spectroscopy and Electron Momentum Spectroscopymentioning

confidence: 99%

“…Table 1 Comparison of the calculated 13 C-NMR chemical shift of the most stable gallic acid conformer in DMSO solvent 66 kinase inhibitors (TKI). The TKIs have different biological activities when installing (click chemistry) various active groups to the quinazoline core using synthetic methods, which have potential applications in biology, pesticides and medicine.…”

Section: Photoelectron Spectroscopy and Electron Momentum Spectroscopymentioning

confidence: 99%

“…11. 66 The conformers are formed by rotations of the hydroxyl and carbonyl groups through the C–O and C–C bonds. As indicated by the colour scheme in this figure, intramolecular hydrogen bonding interactions reveal by the chemical shift with Δ δ ≠ 0 of the carbon pairs δ (C(7)) and δ (C(3)) and Δ δ ′ Δ δ ≠ 0 of the carbon pairs δ (C(4)) and δ (C(6)).…”

Section: Microwave and Infrared Spectroscopymentioning

confidence: 99%

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Section: Photoelectron Spectroscopy and Electron Momentum Spectroscopymentioning

confidence: 99%

Section: Photoelectron Spectroscopy and Electron Momentum Spectroscopymentioning

confidence: 99%

Section: Photoelectron Spectroscopy and Electron Momentum Spectroscopymentioning

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confidence: 99%

Section: Microwave and Infrared Spectroscopymentioning

confidence: 99%

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Interfacial behavior of gallic acid and its alkyl esters in stripped soybean oil in combination with monoacylglycerol and phospholipid

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Intramolecular O···H Hydrogen Bonding of Salicylic Acid: Further Insights from O 1s XPS and ¹H NMR Spectra Using DFT Calculations

Hill

Wang

2023

J. Phys. Chem. A

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Intramolecular hydrogen bonding (HB) is a complex phenomenon that extends beyond a simple valence event, affecting the core electrons of a molecule. Salicylic acid (SA) and its conformers provide an excellent model compound for studying intramolecular HB as the proton donor (H) and acceptor (O) can be toggled by rotating the C–O and C–C bonds to form up to seven potential conformers through various HB. In this study, we computationally investigated intramolecular interactions in SA conformers with and without such HB, by examining their calculated O 1s core electron-binding energy (CEBE) and 1H NMR chemical shifts validated using recent measurements. The quantum mechanically stable SA conformers are fully defined by three rotatable bonds in the compound, which are abstracted as SA(η1η2η3) digital structures, where ηi = 0 if the ηi angles match the most stable SA conformer (000) and η i = 1 otherwise. Our findings suggest that the stability is dominated by the appearance of the intergroup intramolecular HB of Hp···O (where O is in the carboxylic acid functional group and Hp is the phenolic proton in −OHp), and η3 serves as a switch of such HB. As a result, the (η1η20) SA conformers containing such Hp···O HB are more stable than other SA conformers (η1η21) without such the Hp···O HB. The present density functional theory calculations reveal that this Hp···O HB results in splitting of the O 1s CEBEs of two hydroxyl groups (−OH) by up to 1 eV and deshielding the Hp proton 1H NMR (δHp) up to 11.68 ppm for the (η1η20) conformers. Without such Hp···O HB, the O 1s XPS binding energies of two −OH groups will be closely located in the same band, and the 1H NMR chemical shift of the Hp atom will be as small as an 4.09 ppm SA conformer [SA-G(101)]. The present study indicates that the O 1s CEBE splitting between two −OH groups serves as an indicator of the presence of the Hp···O HB in SA conformers, which is also supported by the 1H NMR results.

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Impact of intramolecular hydrogen bonding of gallic acid conformers on chemical shift through NMR spectroscopy

Cited by 6 publications

References 24 publications

Future of computational molecular spectroscopy—from supporting interpretation to leading the innovation

Future of computational molecular spectroscopy—from supporting interpretation to leading the innovation

Interfacial behavior of gallic acid and its alkyl esters in stripped soybean oil in combination with monoacylglycerol and phospholipid

Intramolecular O···H Hydrogen Bonding of Salicylic Acid: Further Insights from O 1s XPS and ¹H NMR Spectra Using DFT Calculations

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Impact of intramolecular hydrogen bonding of gallic acid conformers on chemical shift through NMR spectroscopy

Cited by 6 publications

References 24 publications

Future of computational molecular spectroscopy—from supporting interpretation to leading the innovation

Future of computational molecular spectroscopy—from supporting interpretation to leading the innovation

Interfacial behavior of gallic acid and its alkyl esters in stripped soybean oil in combination with monoacylglycerol and phospholipid

Intramolecular O···H Hydrogen Bonding of Salicylic Acid: Further Insights from O 1s XPS and 1H NMR Spectra Using DFT Calculations

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Product

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Intramolecular O···H Hydrogen Bonding of Salicylic Acid: Further Insights from O 1s XPS and ¹H NMR Spectra Using DFT Calculations