Multinuclear NMR study of the complexes of 6-phospho-d-gluconic acid with W(VI) and Mo(VI)

NMR and DFT studies of the complexation of W(VI) and Mo(VI) with 3-phospho-D-glyceric and 2-phospho-D-glyceric acids

Multinuclear ((1)H, (13)C, (17)O, (31)P, (95)Mo, (183)W) magnetic resonance spectroscopy (1D and 2D) has been used to study the complexation of molybdate(VI) and tungstate(VI) with 3-phospho-D-glyceric and 2-phospho-D-glyceric acids. 3-Phospho-D-glyceric acid forms four and five complexes, respectively, with molybdate and tungstate. These have MO(2)(2+) centres, and involve the carboxylate and the adjacent OH groups. Two isomeric 1:2 (metal-ligand) complexes are detected, in addition to one mononuclear species having MO(3) centres and involving the ligand in a tridentate chelation and a dominant 12:4 species with both tungstate(VI) and molybdate(VI). The dominant 12:4 species can be seen as two 1:2 complexes bound together in a ring through two diphosphometalate moieties, derived from heptamolybdate or heptatungstate, respectively, by inclusion of two phosphate groups from the ligands. Tungstate is also able to form an additional 2:1 tridentate species. 2-Phospho-D-glyceric acid does not interact with tungstate but is able to form one phosphomolybdate species with molybdate, which can be regarded as a heptamolybdate derivative. Density functional theory (DFT) calculations were performed for 1:2 complexes, including calculations on the relative energies of the 1:2 complexes detected in related systems, to validate previously proposed structures. The results are compared with those obtained from multinuclear NMR spectroscopy.

Two new acylgluconic acids from the nearly ripe fruits of Evodia rutaecarpa

Two new acylgluconic acids, trans-feruloylgluconic acid (1) and trans-caffeoylgluconic acid (2), together with three known compounds, myo-inositol (3), phthalic acid dibutyl ester (4), and wuzhuyuamide-I (5), were isolated from the water soluble part of the dried nearly ripe fruits of Evodia rutaecarpa (Juss.) Benth. Their structures were determined by spectroscopic methods, including IR, UV, ESITOFMS, HRSIMS, 1D and 2D NMR spectral analyses.