Mass spectrometry as a tool for studying tautomerism

Furlong, Jorge; Schiavoni, María Alejandra; Castro, Eduardo A.; Allegretti, Patricia Ercilia

doi:10.1134/s1070428008120014

Cited by 21 publications

(16 citation statements)

References 70 publications

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“…Several other studies have detailed the strong clustering observed with 100% water solutions in ESI [56][57][58][59]. MS/MS of the 4-ABA•H + ions isolated at a compensation voltage (CV) of −7.5 V yields (among other product channels) a unique loss of NH 3 , whereas isolation and fragmentation of the ions at CV = −1.5 V yields (among others) a more dominant loss of H 2 O [25]. These observations are consistent with previous investigations into mixed populations of the 4-ABA•H + tautomers [25], and indicate that the peak at CV = −7.5 V is associated with the Nprotonated tautomer and that the O-protonated tautomer transmits at CV = −1.5 V.…”

Section: Resultsmentioning

confidence: 99%

“…T he analysis of tautomers-isomeric species that differ only in the positioning of a labile proton [1] -has challenged mass spectrometry (MS) for many decades [2,3]. In rare cases, orthogonal separation of tautomers prior to MS analysis could be afforded by gas chromatography [4], but the vast majority of cases involve MS analysis of convolved mixtures of tautomers.…”

Section: Introductionmentioning

confidence: 99%

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Studying Gas-Phase Interconversion of Tautomers Using Differential Mobility Spectrometry

Campbell

Yang

Melo

et al. 2016

J. Am. Soc. Mass Spectrom.

125

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Abstract. In this study, we report on the use of differential mobility spectrometry (DMS) as a tool for studying tautomeric species, allowing a more in-depth interrogation of these elusive isomers using ion/molecule reactions and tandem mass spectrometry. As an example, we revisit a case study in which gas-phase hydrogendeuterium exchange (HDX)-a probe of ion structure in mass spectrometry-actually altered analyte ion structure by tautomerization. For the N-and O-protonated tautomers of 4-aminobenzoic acid, when separated using DMS and subjected to subsequent HDX with trace levels of D 2 O, the anticipated difference between the exchange rates of the two tautomers is observed. However, when using higher levels of D 2 O or a more basic reagent, equivalent and almost complete exchange of all labile protons is observed. This second observation is a result of the interconversion of the N-protonated tautomer to the Oprotonated form during HDX. We can monitor this transformation experimentally, with support from detailed molecular dynamics and electronic structure calculations. In fact, calculations suggest the onset of bulk solution phase properties for 4-aminobenzoic acid upon solvation with eight CH 3 OH molecules. These findings also underscore the need for choosing HDX reagents and conditions judiciously when separating interconvertible isomers using DMS.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Studying Gas-Phase Interconversion of Tautomers Using Differential Mobility Spectrometry

Campbell

Yang

Melo

et al. 2016

J. Am. Soc. Mass Spectrom.

125

View full text Add to dashboard Cite

show abstract

“…Mass spectrometry (MS) is very suitable for estimation of the net tautomeric changes under such structural modifications, because the external factors like solvents, intermolecular interactions, etc., can be excluded by transferring the tautomeric system into the gas phase, where the process becomes truly unimolecular 6. The use of MS is based on the assumption that there is no significant interconversion between the tautomers in the gas phase following electron ionization (EI) 7. Hence, EI‐MS provides a snapshot of the tautomeric gas‐phase mixture and normally the M + .…”

Section: Methodsmentioning

confidence: 99%

Gas-phase tautomerism in hydroxy azo dyes - from 4-phenylazo-1-phenol to 4-phenylazo-anthracen-1-ol

Nedeltcheva

Kurteva

Topalova

2010

Rapid Commun. Mass Spectrom.

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The tautomeric constants of a series of azo dyes were estimated in the gas phase by using electron ionization mass spectrometry. It was shown that the relative amount of the keto tautomer increases from 4-phenylazo-1-phenol to 4-phenylazo-anthracen-1-ol, thus confirming the quantum-chemical predictions. The existence of the enol tautomer of 4-phenylazo-anthracen-1-ol is shown for the first time by mass spectrometry in the gas phase. This finding is supported by flash photolysis measurements in solution.

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“…Mass spectrometry has been successfully used for tautomeric study [46][47][48], and hence it has been tried to use mass spectrometry for dCurc different structures elucidation by analogy to the tautomerism. Mass spectrometric decomposition of deprotonated demethoxycurcumin (negative ion [dCurc-H] − ) led to the formation of fragment ions at / 217, and 187, whereas deprotonated curcumin yielded only ion at / 217 and deprotonated bisdemethoxycurcumin yielded only ion 187 [49,50].…”

Section: Resultsmentioning

confidence: 99%

Demethoxycurcumin-Metal Complexes: Fragmentation and Comparison with Curcumin-Metal Complexes, as Studied by ESI-MS/MS

Ostrowski

Śniecikowska

Hoffmann

et al. 2013

Journal of Spectroscopy

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Two questions are asked: the first is if the lack/presence of methoxyl moiety at aromatic ring essentially affects the stability of curcuminoid-metal complexes, and the second is if it is possible that in the metal complexes one of the possible demethoxycurcumin structures predominates. To answer the first question, the ESI-MS/MS spectra were taken of ions containing demethoxycurcumin, curcumin, and metal cation (e.g., ion [dCurc + Curc-H + Pb]+), and in order to answer the second question the ESI-MS/MS spectra were recorded of ions containing demethoxycurcumin and metal cation (e.g., ion [dCurc-H + Zn]+). An interpretation of the mass spectra has indicated that (i) for some metals, curcumin-metal complexes are more stable than demethoxycurcumin-metal complexes and for some metals vice versa, and (ii) in demethoxycurcumin-metal complexes structure B1 [(1E,4Z,6E)-5-hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxyphenyl)hepta-1,4,6-trien-3-one] is more stable than structure B2 [(1E,4Z,6E)-5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl)hepta-1,4,6-trien-3-one].

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Mass spectrometry as a tool for studying tautomerism

Abstract: The review contains new data on tautomerism of organic compounds belonging to different classes, which were obtained by mass spectrometry and confirmed by quantum-chemical calculations.

Cited by 21 publications

References 70 publications

Studying Gas-Phase Interconversion of Tautomers Using Differential Mobility Spectrometry

Studying Gas-Phase Interconversion of Tautomers Using Differential Mobility Spectrometry

Gas-phase tautomerism in hydroxy azo dyes - from 4-phenylazo-1-phenol to 4-phenylazo-anthracen-1-ol

Demethoxycurcumin-Metal Complexes: Fragmentation and Comparison with Curcumin-Metal Complexes, as Studied by ESI-MS/MS

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