Theoretical and experimental study of the structure and stability of multiply Na-substituted glucose and 2,4,6-trihydroxyacetophenone derivatives |
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Authors: | O P Charkin N M Klimenko B -G Chen S -H Lin C -H Chen |
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Institution: | 1.Institute of Problems of Chemical Physics,Russian Academy of Sciences,Chernogolovka, Moscow oblast,Russia;2.Lomonosov State Academy of Fine Chemical Technology,Moscow,Russia;3.Institute of Atomic and Molecular Sciences,Academia Sinica,Taipei, Taiwan,R.O.C.;4.Genomics Research Center,Academia Sinica,Nankang, Taipei,Taiwan |
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Abstract: | The equilibrium geometric parameters and the energetic and spectroscopic characteristics of low lying conformers for series
of polyhydroxyl molecules and ions in which sodium atoms are successively substituted for the hydroxyl hydrogen atoms have
been calculated by the density functional theory B3LYP method with the 6−31G* and 6−311+G** basis sets. The glucose derivatives
Glu − nH + nNa] and Glu − nH + (n + 1)Na]+ (n = 1−5) and the 2,4,6-trihydroxyacetophenone derivatives THAP − nH + nNa] and THAP − nH + (n + 1)Na]+ (n = 1−4) have been considered. The affinities of the neutral Glu − nH + nNa] and THAP − nH + nNa] molecules for adding Na+ cations, as well as the energies of successive substitution of Na atoms for H atoms in the Glu and THAP molecules and the
Glu+ and THAP+ ions in their reaction with sodium acetate molecules, have been estimated. Computations show that the first substitution
of Na for H in ions is slightly exothermic and, presumably, can spontaneously occur under common conditions. Further substitutions
are endothermic, but the required energy inputs are small. Therefore, successive substitutions for two, three, or more hydroxyl
H atoms in the molecules and ions under consideration are possible at relatively low energy inputs. The computation results
and conclusions are compared with the MALDI TOF mass spectral data for Na-substituted glucose and 2,4,6-trihydroxyacetophenone
derivatives in the glucose + CH3COONa + THAP] system where, in addition to common Glu · Na+ and THAP · Na+ ion-molecular complexes, multiply substituted positive ions of the Glu − nH + (n + 1)Na]+ (n = 1−4) and THAP − nH + (n + 1)Na]+ (n = 1−3) type have been identified. |
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