Selective deprotection of tethered glycoderivatives with unsaturated spacer

Pascariu, Mihai-Cosmin; Rusnac, Lucian Mircea

doi:10.1515/hc.2011.022

Cited by 1 publication

(3 citation statements)

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“…The minimum ∆ f H and ∆ f G values (kcal/mol) and Equations ( 1) and (2) were used, where ∆ f H (M) is the molecule enthalpy, ∆ f H (M + ) is the molecular ion enthalpy and Σ∆ f H (F) is the sum of the fragment enthalpies. The meanings are similar for ∆ f G. Although easy to calculate, the database did not contain ionization energies because molecular ions do not appear in the electron ionization mass spectra of di-O-isopropylidene monosaccharides [29]. The ions at m/z 245, m/z 187 and m/z 127 had calculated energy for all structures (1)(2)(3)(4)(5)(6)(7)(8)(9)(10).…”

Section: Resultsmentioning

confidence: 99%

“…The meanings are similar for ΔfG. Although easy to calculate, the database did not contain ionization energies because molecular ions do not appear in the electron ionization mass spectra of di-O-isopropylidene monosaccharides [29]. The ions at m/z 245, m/z 187 and m/z 127 had calculated energy for all structures (1)(2)(3)(4)(5)(6)(7)(8)(9)(10).…”

Section: Resultsmentioning

confidence: 99%

“…The meanings are similar for ΔfG. Although easy to calculate, the database did not contain ionization energies because molecular ions do not appear in the electron ionization mass spectra of di-O-isopropylidene monosaccharides [29]. The ions at m/z 245, m/z 187 and m/z 127 had calculated en- The enthalpies and Gibbs energies that were computed using semi-empirical methods RM1, PM7 and DFT (at the B3LYP/6-31G level of theory) for each candidate structure are shown in Tables 3-6.…”

Section: Resultsmentioning

confidence: 99%

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Computed Mass-Fragmentation Energy Profiles of Some Acetalized Monosaccharides for Identification in Mass Spectrometry

et al. 2022

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Our study found that quantum calculations can differentiate fragmentation energies into isomeric structures with asymmetric carbon atoms, such as those of acetalized monosaccharides. It was justified by the good results that have been published in recent years on the discrimination of structural isomers and diastereomers by correlating the calculated mass energy fragmentation profiles with their mass spectra. Based on the quantitative structure–fragmentation relationship (QSFR), this technique compares the intensities of primary ions from the experimental spectrum using the mass energy profiles calculated for the candidate structures. Maximum fit is obtained for the true structure. For a preliminary assessment of the accuracy of the identification of some di-O-isopropylidene monosaccharide diastereomers, we used fragmentation enthalpies (ΔfH) and Gibbs energies (ΔfG) as the energetic descriptors of fragmentation. Four quantum chemical methods were used: RM1, PM7, DFT ΔfH and DFT ΔfG. The mass energy database shows that the differences between the profiles of the isomeric candidate structures could be large enough to be distinguished from each other. This database allows the optimization of energy descriptors and quantum computing methods that can ensure the correct identification of these isomers.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…The meanings are similar for ΔfG. Although easy to calculate, the database did not contain ionization energies because molecular ions do not appear in the electron ionization mass spectra of di-O-isopropylidene monosaccharides [29]. The ions at m/z 245, m/z 187 and m/z 127 had calculated en- The enthalpies and Gibbs energies that were computed using semi-empirical methods RM1, PM7 and DFT (at the B3LYP/6-31G level of theory) for each candidate structure are shown in Tables 3-6.…”

Section: Resultsmentioning

confidence: 99%

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