Variations in reactivity of lone-pair electrons due to intramolecular hydrogen bonding as observed by Penning ionization electron spectroscopy

Ohno, Koichi; Imai, Keitaro; Harada, Yoshiya

doi:10.1021/ja00312a047

Cited by 42 publications

(36 citation statements)

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“…The stability of this conformer was attributed to the presence of an intramolecular hydrogen bond of the type OH…N, that has also been found to operate in other similar molecules [20,21]. This result has received support from theoretical calculations carried out at different levels of approximation [3][4][5][6][7][8][9][10][11][12][13][14][15]. However, different methods of calculation do not fully agree with respect to the relative order of stability of the remaining conformers, despite some general consensus has emerged from the whole set of calculations already carried out: (a) conformers where OH…N or NH…O intramolecular hydrogen bonding operate have an increased stability (the estimated stabilizing energies for the stronger intramolecular H-bonding of each type-OH…N, in g H Gg H , and NH…O in gGt -amount to ca.…”

Section: Introductionsupporting

confidence: 53%

“…Conformational isomerism in AE has been the subject of several theoretical and experimental studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. For the isolated molecule situation and in the gaseous phase, it has been shown that intramolecular hydrogen bonding plays a decisive role in stabilizing those conformations which correspond to the most stable conformational states of the studied molecule [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A concerted SCF-MO ab initio and vibrational spectroscopic study of the conformational isomerism in 2-aminoethanol

Silva

Duarte

Fausto

1999

Journal of Molecular Structure

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Conformational isomerism in isolated and liquid 2-aminoethanol was investigated by a concerted molecular orbital and vibrational spectroscopic approach. The molecular structures, relative energies, dipole moments and vibrational spectra (both infrared and Raman) of the various possible conformers of the studied compound were calculated, using the extended 6-31G* basis set at the HF-SCF ab initio level of theory. The theoretical results were then used to interpret infrared and Raman data obtained under different experimental conditions. It was found that none of the most populated conformational states existing in the pure liquid (where intermolecular H-bonding occurs extensively)-the gGt and tTt conformers-, correspond to the conformational ground state for the isolated 2-aminoethanol molecule-the intramolecularly H-bonded g H Gg H conformer.

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Section: Introductionsupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

A concerted SCF-MO ab initio and vibrational spectroscopic study of the conformational isomerism in 2-aminoethanol

Silva

Duarte

Fausto

1999

Journal of Molecular Structure

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“… a Hydrogen atom abstraction reaction efficiency = second-order hydrogen atom abstraction rate constant / collision rate constant (k exp /k coll ). b Calculated at the B3LYP/aug-cc-pVTZ//B3LYP/cc-pVTZ level of theory. c Reference 55. d Reference 56. …”

Section: Figures and Tablesmentioning

confidence: 99%

Gas-Phase Reactivity of Protonated 2-, 3-, and 4-Dehydropyridine Radicals Toward Organic Reagents

et al. 2009

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In order to explore the effects of the electronic nature of charged phenyl radicals on their reactivity, reactions of the three distonic isomers of ndehydropyridinium cation (n = 2, 3 or 4) have been investigated in the gas phase by using Fourier-transform ion cyclotron resonance mass spectrometry. All three isomers react with cyclohexane, methanol, ethanol and 1-pentanol exclusively via hydrogen atom abstraction, and with allyl iodide mainly via iodine atom abstraction, with a reaction efficiency ordering: 2 > 3 > 4. The observed reactivity ordering correlates well with the calculated vertical electron affinities of the charged radicals (i.e., the higher the vertical electron affinity, the faster the reaction). Charged radicals 2 and 3 also react with tetrahydrofuran exclusively via hydrogen atom abstraction, but the reaction of 4 with tetrahydrofuran yields products arising from nonradical reactivity. The unusual reactivity of 4 is likely to result from the contribution of an ionized carbenetype resonance structure that facilitates nucleophilic addition to the most electrophilic carbon atom (C-4) in this charged radical. The influence of such a resonance structure on the reactivity of 2 is not obvious, and this may be due to stabilizing hydrogen-bonding interactions in the transition states for this molecule. Charged radicals 2 and 3 abstract a hydrogen atom from the substituent in both phenol and toluene, but 4 abstracts a hydrogen atom from the phenyl ring -a reaction that is unprecedented for phenyl radicals. Charged radical 4 reacts with tert-butyl isocyanide mainly by hydrogen cyanide (HCN) abstraction while CN abstraction is the principal reaction for 2 and 3. The different reactivity observed for 4 (compared to 2 and 3) is likely to result from different charge and spin distributions of the reaction intermediates for these charged radicals.

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“…This also proved to be the case when PALDI matrices were utilized, in contrast to the predominant mechanism of charge transfer which prevails when dealing with small molecules 1. This is understandable since the monomers of polystyrene and polyethylene glycol have quite high ionization potentials: 8.48–8.58 eV for styrene (vertical)41, 42 and 10.55 eV for ethylene glycol (vertical),43, 44 which are considerably higher than those of the PALDI matrices, for instance 6.31 eV (vertical) in the case of 3DIO.…”

Section: Resultsmentioning

confidence: 99%

Matrix‐assisted and polymer‐assisted laser desorption/ionization time‐of‐flight mass spectrometric analysis of low molecular weight polystyrenes and polyethylene glycols

Woldegiorgis

Löwenhielm

Björk

et al. 2004

Rapid Comm Mass Spectrometry

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Recently, matrices based on oligomers of dioxin and thiophene (polymer-assisted laser desorption/ionization (PALDI)) have been described for mass spectrometric (MS) analysis of low molecular weight compounds (Woldegiorgis A, von Kieseritzky F, Dahlstedt E, Hellberg J, Brinck T, Roeraade J. Rapid Commun. Mass Spectrom. 2004; 18: 841-852). In this paper, we report the use of PALDI matrices for low molecular weight polymers. An evaluation with polystyrene and polyethylene glycol showed that no charge transfer ionization occurs. Ionization is mediated through metal ion adduction. Comparison of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) data for two very low molecular weight polymers with data obtained from size-exclusion chromatography (SEC) revealed a systematic difference regarding mean molecular weight and dispersity. Further, the mass spectra obtained with PALDI matrices had a higher signal-to-noise ratio than the spectra obtained with conventional matrices. For polymers with higher molecular weights (>1500 Da), the conventional matrices gave better performance. For evaluation of the MALDI spectra, three non-linear mathematical models were evaluated to model the cumulative distributions of the different oligomers and their maximal values of Mw, Mn and PDI. Models based on sigmoidal or Boltzmann equations proved to be most suitable. Objective modeling tools are necessary to compare different sample and instrumental conditions during method optimization of MALDI analysis of polymers, since the bias between MALDI and SEC data can be misleading.

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Variations in reactivity of lone-pair electrons due to intramolecular hydrogen bonding as observed by Penning ionization electron spectroscopy

Cited by 42 publications

References 0 publications

A concerted SCF-MO ab initio and vibrational spectroscopic study of the conformational isomerism in 2-aminoethanol

A concerted SCF-MO ab initio and vibrational spectroscopic study of the conformational isomerism in 2-aminoethanol

Gas-Phase Reactivity of Protonated 2-, 3-, and 4-Dehydropyridine Radicals Toward Organic Reagents

Matrix‐assisted and polymer‐assisted laser desorption/ionization time‐of‐flight mass spectrometric analysis of low molecular weight polystyrenes and polyethylene glycols

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