Structural and Energetic Aspects of the Protonation of Phenol, Catechol, Resorcinol, and Hydroquinone

Bouchoux, Guy; Defaye, Dirk; McMahon, T. B.; Likholyot, Alexander; Mó, Otília; Yáñez, Manuel

doi:10.1002/1521-3765(20020703)8:13<2900::aid-chem2900>3.0.co;2-t

Cited by 60 publications

(48 citation statements)

References 6 publications

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“…The differing results for 1,4-benzoquinone (Q), hydroquinone (H 2 Q), and quinhydrone (Q · H 2 Q) appear to be dictated by solution-phase, and not gas-phase, behavior. For example, the gas-phase basicity of hydroquinone was recently determined to be 808.4 kJ/mol [55] while that of 1,4-benzoquinone is slightly lower at 799.1 kJ/mol [56]. If gas-phase basicity dominated the charge reduction phenomenon, then cytochrome c admixed with hydroquinone would be expected to have a lower ACS distribution than cytochrome c admixed with 1,4-benzoquinone.…”

Section: Resultsmentioning

confidence: 74%

Shifts in protein charge state distributions with varying redox reagents in nanoelectrospray triple quadrupole mass spectrometry

Zhao

Wood

Bruckenstein

2005

J. Am. Soc. Mass Spectrom.

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The influence of a number of redox reagents on the charge state distribution in nanoelectrospray mass spectrometry was examined using cytochrome c and ubiquitin. The redox active species investigated were: 1,4-benzoquinone, quinhydrone, tetracyanoquinodimethane (TCNQ), hydroquinone, and ascorbic acid. The redox active species was mixed with the protein sample before injection into the nanoelectrospray emitter, and mass spectra were acquired using a triple quadrupole mass spectrometer. Under the same experimental conditions, the charge state distribution of cytochrome c was observed to shift from a weighted average charge state of 14.25 (in the absence of redox species) to 7.10 in the presence of 1,4-benzoquinone. When quinhydrone was mixed with cytochrome c, the charge state distribution of the protein also shifted to lower charge states (weighted average charge state ϭ 9.43), indicative of less charge state reduction for quinhydrone than with 1,4-benzoquinone. Addition of the redox reagent had little effect on the conformation of cytochrome c, as indicated by far ultraviolet circular dichroism spectra. In contrast, the reagents TCNQ, hydroquinone, and ascorbic acid exhibited negligible effects on the observed charge state distribution of the protein. The differing results for these redox reagents can be rationalized in terms of the redox half reactions involving these species. The results observed with ubiquitin upon adding quinhydrone were analogous to those observed with cytochrome c. The multiple charging phenomenon, however, also increases the complexity of the mass spectra, and may concomitantly decrease dynamic range, reduce sensitivity, and compromise mixture component analysis [4,5]. Mass spectral deconvolution procedures are frequently useful in reducing spectral complexity [6], but are decreasingly effective as the mixture complexity increases.The charge state distributions of macromolecules can be influenced by many factors, such as the analyte structure/conformation [7][8][9][10][11] [18,20,34,35]. Many of these factors are interrelated. For example, changes in the solution pH, solvent, and heating conditions can alter the conformation of a protein, thereby affecting the observed charge state distribution. Three strategies have been reported in the literature in an effort to manipulate and simplify the observed multiple charge state distributions. One condensed-phase strategy takes place by modifying the solution conditions such as pH [36]. A second condensed-phase strategy invoked to control the observed charge state distribution in ESI is to admix base molecules with different gas-phase basicities into the analyte mixture [37]. The other strategy takes place in the gas-phase; this has been achieved either by utilizing a post ion/ion reaction within an ion-trap spectrometer to reduce multiple charge states [19, 38 -42], or by utilizing a "neutralization chamber" before the mass analyzer, to reduce multiple charge states [43][44][45][46][47]. These gas-phase approaches have demonstrated great effec...

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Section: Resultsmentioning

confidence: 74%

Shifts in protein charge state distributions with varying redox reagents in nanoelectrospray triple quadrupole mass spectrometry

Zhao

Wood

Bruckenstein

2005

J. Am. Soc. Mass Spectrom.

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“…More importantly, the existence of an IHB may have a nonnegligible effect on the intrinsic basicity or acidity of the system. As it has been shown, for tropolone [3], β-chalcogenvinylaldehydes [4], resorcinol [5], and bis(tetramethylguanidine) superbases and related systems [6,7] the perturbation of the IHB upon protonation, or its disappearance in deprotonation processes, has a strong effect on the gas-phase basicity and acidity of these compounds. Similarly, the formation of an intramolecular hydrogen bond in the protonated species is responsible for a significant enhancement of the intrinsic basicity of some acid anhydrides [8].…”

Section: Introductionmentioning

confidence: 99%

The Role of Intramolecular Hydrogen Bonds vs. Other Weak Interactions on the Conformation of Hyponitrous Acid and Its Mono- and Dithio-Derivatives

et al. 2005

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High level ab initio and density functional theory calculations have been carried out to investigate the relative stability of the different conformers of hyponitrous acid and its mono-and dithioderivatives. Geometries and vibrational frequencies were obtained at the B3LYP/6-311+G(d,p) level and final energies through B3LYP/6-311++G(3df,2pd) single point calculations. The reliability of this theoretical scheme has been assessed by comparing these DFT results with those obtained at the G3 level of theory, for some suitable cases. The cis conformers of hyponitrous acid and its mono-and dithio-derivatives are systematically more stable than the trans ones because in the cis conformation a dative interaction between the nitrogen-lone pairs and the σ * NX antibonding orbital is significantly favored. Quite interestingly, in general, the conformers presenting an intramolecular hydrogen bond (IHB) are not the global minima of the corresponding potential energy surfaces and only for hyponitrous acid the conformer with a OH · · · O IHB is slightly more stable than the cis conformer without IHB. The low stability of the tautomers with IHB is closely related with another weak intramolecular interaction which involves the lone-pairs of the chalcogen atoms and the π * NN antibondig orbital, and which is significantly perturbed when the IHB is formed.

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“…The first protonation seems to occur at the βN as suggested in the literature [17]. Obviously the electron donation of the two hydroxyl groups located at the o-and p-positions of ring B is more than that of the p-located OH group on the A; therefore, βN becomes electron rich compared to αN.…”

Section: First Protonationmentioning

confidence: 99%

Synthesis, Characterization and Spectroscopic Studies on Azo-Hydrazone Tautomerism and Acidity Constants of Certain 4-(Phenyldiazenyl) Benzene-1,3-Diol Derivatives

Berber¹,

Ateş²,

Özkütük³

2016

BTDB

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In this study, monoazo dyes were synthesized through the diazotization of several substituted aminobenzenes and couplings with benzene-1,3-diols. The chemical structures of these compounds were characterized using spectroscopic techniques. The tautomeric properties of the 4-(phenyldiazenyl)benzene-1,3-diol derivative compounds were examined using UV-Vis. spectrophotometry in pure polar or apolar media (dimethyl sulfoxide, ethanol, chloroform, benzene and cyclohexane) under acidic and basic conditions at 25±1 °C, 35±1 °C and 45±1 °C. The percentage of the azo-hydrazone tautomers was calculated for all of the compounds. The UV-Vis. analysis reveals that the azo form is dominant in the presence of azo-hydrazone tautomerism for all azo dyes. Concurrently, the acidity constants for these derivatives were determined using a UV-Vis. spectroscopic technique at 25 °C (0.1 °C).

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Structural and Energetic Aspects of the Protonation of Phenol, Catechol, Resorcinol, and Hydroquinone

Cited by 60 publications

References 6 publications

Shifts in protein charge state distributions with varying redox reagents in nanoelectrospray triple quadrupole mass spectrometry

Shifts in protein charge state distributions with varying redox reagents in nanoelectrospray triple quadrupole mass spectrometry

The Role of Intramolecular Hydrogen Bonds vs. Other Weak Interactions on the Conformation of Hyponitrous Acid and Its Mono- and Dithio-Derivatives

Synthesis, Characterization and Spectroscopic Studies on Azo-Hydrazone Tautomerism and Acidity Constants of Certain 4-(Phenyldiazenyl) Benzene-1,3-Diol Derivatives

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