Mass spectral studies of unsaturated carboxylic acids—I: Some cyclic and acyclic βγ‐unsaturated acids

Alexander, Roger G.; Bigley, D. B.; Todd, John F. J.

doi:10.1002/oms.1210061013

Cited by 5 publications

(3 citation statements)

References 14 publications

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“…The crude product was purified by flash column chromatography over silica eluting with 15% methanol/85% ethyl acetate to yield 9 as a viscous foaming liquid (61 mg, 80%). 1 80,81 1-(Benzyloxy)-N-( (10). The protected backbone 5 (200 mg, 0.410 mmol) was dissolved in TFA (5 mL) and CH 2 Cl 2 (5 mL).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

A Combination of Factors: Tuning the Affinity of Europium Receptors for Phosphate in Water

2019

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Although recognition of hard anions by hard metal ions is primarily achieved via direct coordination, electrostatic and hydrogen-bonding interactions also play essential roles in tuning the affinity of such supramolecular receptors for their target. In the case of EuIII hydroxypyridinone-based complexes, the addition of a single charged group (−NH3 +, −CO2 –, or −SO3 –) or neutral hydrogen-bonding moiety (−OH) peripheral to the open coordination site substantially affects the affinity of the metal receptor for phosphate in water at neutral pH. A single primary ammonium increases the first association constant for phosphate in neutral water by 2 orders of magnitude over its neutral analogue. The addition of a peripheral alcohol group also increases the affinity of the receptor but to a lesser degree (21-fold). On the other hand, negatively charged complexes bearing either a carboxylate or sulfate moiety have negligible affinity for phosphate. Interestingly, the peripheral group also influences the stoichiometry of the lanthanide receptor for phosphate. While the complex bearing a −NH3 + group binds phosphate in a 1:2 ratio, those with −OH and H (control) both form 1:3 complexes. Although the positively charged EuIII-Lys-HOPO has the highest K a1 for phosphate, a greater increase in luminescence intensity (36-fold) is observed with the neutral EuIII-Ser-HOPO complex. Notably, whereas the affinity of the EuIII complexes for phosphate is substantially influenced by the presence of a single charged group or hydrogen-bond donor, their selectivity for phosphate over competing anions remains unaffected by the addition of the peripheral groups.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

A Combination of Factors: Tuning the Affinity of Europium Receptors for Phosphate in Water

2019

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“…3-Butenoic acid (4) displays an appreciably different spectrum; loss of CO assumes greater importance and losses of H 2 0 , OH' and CH3' are relatively much less than in acids 1-3. The cyclic isomer (5) produces a characteristic intense [M -HI' peak, but the presence of prominent ions at mlz 71, 69, 68 and 58 show that this acid has features in common with its four isomers. As with the crotonic acids, mlz 45 is a doublet, [COOH]' and [&H,O]'.…”

Section: Normal Mass Spectra and Heats Of Formation Of The Molecular mentioning

confidence: 99%

Metastable ion studies. XII—Molecular and fragment ion structures for isomeric C₄H₆O₂ acids

Holmes

Terlouw

Vijfhuizen

et al. 1979

Org. Mass Spectrom.

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Metastable peak characteristics, ionization and appearance energy data and isotopic labelling experiments have been applied to a study of the fragmentation behavioUr of the molecnlar ions of the isomeric C A O , acids, cis and trans-uotonic acids, methacrylic acid, butenoic acid and cydopropane carboxylic acid. Prior to the losses of H,O and CH,, all the metastable molecular ions rearrange to [cis-crotonic acid]+' ions. Loss of H,O, which generates a composite metastable peak, is proposed to yield vhylketene and/or cydobutenone molecular ions. Detailed mechanisms are presented for the isomerbations of the various molecular ions and for the above fragmentations. Ionized 3-butenoic and cydopropane carboxylic acids display a major loss of CO from their metastable ions, a minor prows in the other isomers. The metastable peaks consist of two components and these are ascribed to the formation of propen-1-01 and aUyl alcohol as daughter ions. Some comparative data are presented for the isomeric C&O, aads, tiglk acid, angelic acid and seneaoic acid. INTRODUCllONIt has long been known that fragmentations of many simple ionized olefins are preceded by rearrangements sufficiently extensive to lead to the random statistical loss of labelled and unlabelled groups of carbon and hydrogen atoms, and it has been widely concluded that the molecular ions decompose via a single structure or a mixture of common i0ns.l The more complex isomeric 1, l-di-and tri-alkyl substituted ethylenes have closely similar mass spectra, but in these larger molecules it is believed that the unrearranged molecular ions fragment over different potential surfaces to yield a common daughter ion from which all further reactions pr0ceed.2.~ In general (although not invariably) the effect of introducing a heteroatom into such molecules is to reduce the interconvertibility of their molecular ions, thus rendering more certain the identification of ion structures. Mass spectra1 studies of ethylenes having a single carboxyl substituent are few, although some dibasic ethylenic acids have received detailed attent i~n .~ The higher homologues of some P,yunsaturated acids have been investigated' as have the methyl esters of some hexenoic acids.6Our interest in the simple unsaturated carboxylic acids was aroused by a brief survey of their normal mass spectra and the complex shapes of the metastable peaks associated with their primary fragmentations. In this paper we report observations on metastable peaks accompanying the losses of H,O, CH,' and CO from all acids of formula C4H60, and we discuss the isomerizations of the molecular ions which precede these fragmentations. The analogous reactions of the corresponding methyl and ethyl esters are discussed elsewhere.' ~~ RESULTS AND DISCUSSIONNormal mass spectra and heats of formation of the molecular ionsThe 70 eV mass spectra of cis-crotonic acid (l), wunscrotonic acid (2), methacrylic acid (3), 3-butenoic acid The ionization energies (I(M)) of the five acids were obtained from their photoelectron (PE) spectra; these ...

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“…The results indicated that dehydration (−18) occurred easily in seco -sativenes with strong abundance of dehydration peak observed in 1 - 8 , and similar reports were found in other studies ( McLafferty and Gohike, 1959 ; Alén, 1987 ; Nawamaki and Kuroyanagi, 1996 ; Sun et al, 2012 ; Giri et al, 2017 ; Qian et al, 2018 ). This may be due to an electron impact inducing fragmentations of alkene monocarboxylic acids to form an active OH ion, which combines an available methyl-hydrogen atom to one lost molecule of H 2 O (−18) through the McLafferty rearrangement in a six-membered system ( Baldas et al, 1969 ; Alexander et al, 1972 ). The molecular ion peak [M+H] + of 1 – 7 and 9 was not easily observed in the UPLC-Q-TOF-MS/MS profile, whereas [M+Na] + and [M+H-H 2 O] + abundances of these compounds were relatively strong.…”

Section: Discussionmentioning

confidence: 99%

UPLC-Q-TOF-MS/MS Analysis of Seco-Sativene Sesquiterpenoids to Detect New and Bioactive Analogues From Plant Pathogen Bipolaris sorokiniana

Wang

Yang

et al. 2022

Front. Microbiol.

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Seco-sativene sesquiterpenoids are an important member of phytotoxins and plant growth regulators isolated from a narrow spectrum of fungi. In this report, eight seco-sativene sesquiterpenoids (1–8) were first analyzed using the UPLC-Q-TOF-MS/MS technique in positive mode, from which their mass fragmentation pathways were suggested. McLafferty rearrangement, 1,3-rearrangement, and neutral losses were considered to be the main fragmentation patterns for the [M+1]+ ions of 1–8. According to the structural features (of different substitutes at C-1, C-2, and C-13) in compounds 1–8, five subtypes (A–E) of seco-sativene were suggested, from which subtypes A, B/D, and E possessed the diagnostic daughter ions at m/z 175, 189, and 203, respectively, whereas subtype C had the characteristic daughter ion at m/z 187 in the UPLC-Q-TOF-MS/MS profiles. Based on the fragmentation patterns of 1–8, several known compounds (1–8) and two new analogues (9 and 10) were detected in the extract of plant pathogen fungus Bipolaris sorokiniana based on UPLC-Q-TOF-MS/MS analysis, of which 1, 2, 9, and 10 were then isolated and elucidated by NMR spectra. The UPLC-Q-TOF-MS/MS spectra of these two new compounds (9 and 10) were consistent with the fragmentation mechanisms of 1–8. Compound 1 displayed moderate antioxidant activities with IC50 of 0.90 and 1.97 mM for DPPH and ABTS+ scavenging capacity, respectively. The results demonstrated that seco-sativene sesquiterpenoids with the same subtypes possessed the same diagnostic daughter ions in the UPLC-Q-TOF-MS/MS profiles, which could contribute to structural characterization of seco-sativene sesquiterpenoids. Our results also further supported that UPLC-Q-TOF-MS/MS is a powerful and sensitive tool for dereplication and detection of new analogues from crude extracts of different biological origins.

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Mass spectral studies of unsaturated carboxylic acids—I: Some cyclic and acyclic βγ‐unsaturated acids

Cited by 5 publications

References 14 publications

A Combination of Factors: Tuning the Affinity of Europium Receptors for Phosphate in Water

A Combination of Factors: Tuning the Affinity of Europium Receptors for Phosphate in Water

Metastable ion studies. XII—Molecular and fragment ion structures for isomeric C₄H₆O₂ acids

UPLC-Q-TOF-MS/MS Analysis of Seco-Sativene Sesquiterpenoids to Detect New and Bioactive Analogues From Plant Pathogen Bipolaris sorokiniana

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Mass spectral studies of unsaturated carboxylic acids—I: Some cyclic and acyclic βγ‐unsaturated acids

Cited by 5 publications

References 14 publications

A Combination of Factors: Tuning the Affinity of Europium Receptors for Phosphate in Water

A Combination of Factors: Tuning the Affinity of Europium Receptors for Phosphate in Water

Metastable ion studies. XII—Molecular and fragment ion structures for isomeric C4H6O2 acids

UPLC-Q-TOF-MS/MS Analysis of Seco-Sativene Sesquiterpenoids to Detect New and Bioactive Analogues From Plant Pathogen Bipolaris sorokiniana

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Metastable ion studies. XII—Molecular and fragment ion structures for isomeric C₄H₆O₂ acids