Characterization of oxovanadium (IV) complexes of d-gluconic and d-saccharic acids and their bioactivity on osteoblast-like cells in culture

Oxovanadium (IV) complexes of the alpha-hydroxycarboxylic ligands D-gluconic and D-saccharic acids of stoichiometry Na(2)[VO(gluconate)(2)].H(2)O, K(2)[VO(saccharate)(2)].4H(2)O, Na(4)[VO(gluconate)(2)].2H(2)O and K(5)[VO(saccharate)(2)].4H(2)O were obtained in aqueous solutions; the first two in acid, the other two in alkaline media. They were characterized by infrared and UV-Vis spectroscopies, thermoanalytical (thermogravimetric and differential thermal analysis) data and magnetic susceptibility measurements. The complexes were found to be mononuclear, possessing the VO(2+) moiety, and the thorough analysis of the spectral data allowed the determination of the characteristics of the metal-to-ligand interactions. The biological activities of these complexes on the proliferation, differentiation and glucose consumption were tested on osteoblast-like cells in culture. Comparisons of these effects and those of the oxovanadium (IV) cation and the free ligands were performed. Different behaviors could be observed for the complexes obtained at acidic or alkaline pH-values, as well as for the different cellular types. The free ligands did not show any biological effect.

Spectroscopic study of the interactions of alkali fluorides with D-xylose

The interactions of alkali fluorides with D-xylose have been studied by X-ray diffraction (XRD), infrared spectroscopy (IR), nuclear magnetic resonance (NMR, 1H and 13C) and atomic absorption spectrophotometry. KF and CsF form complexes with D-xylose in a 1:1 molar ratio. These complexes can be obtained by solid state milling the reactants in an agate mortar or from methanolic solutions of the sugar and the salt. LiF and NaF do not form complex with D-xylose. IR and XRD prove the identical nature of the complexes obtained by milling and from solution. IR spectra indicate strong perturbation of the OH stretching vibrations with considerable shifts to lower frequencies, which must be caused by strong hydrogen bond formation to the fluorine anion. The perturbations of C-O bond are weak, indicating that cation binding to the oxygen atoms is not the main interaction responsible for the complex formation. 1H NMR spectra of the D-xylose-KF complex dissolved in deuterium oxide is equal to that of pure D-xylose, indicating the destruction of the complex in solution. The complex is stable in DMSO, and 13C spectra of the complex in DMSO-d6 and in solid state (CPMAS) spectra are in accordance with the observed interactions in the IR spectra. As far as we know, this is the first report of a sugar-halide salt complex in which the anion instead of the cation provides the binding forces.

Carbohydrate-derived alkylcobalt carbonyl:([(1,2:5,6-di-O,O-isopropylidene-alpha-D-glucofuranos-3-yl)oxycarbonyl]methyl)cobalt tricarbonyl triphenylphosphene

A carbohydrate-derivative alkylcobalt carbonyl,([(1,2:5,6-di-O,O-isopropylidene-alpha-D-glucofuranos-3-yl)oxycarbonyl]methyl)cobalt tricarbonyl triphenylphosphene(3) was prepared and characterized by IR, NMR, and CD spectra, as well as by X-ray diffraction. The supramolecular chemistry in the crystalline P2(1)2(1)2(1) (chiral) phase and in solution was analyzed and compared. The bulky carbohydrate-based ligand stabilized one chiral conformation, which, however, is less ordered than for analogous compounds with more flexible and less bulky chiral groups. Intermolecular, H-bond interactions are more important in the P2(1)2(1)2(1) phase of complex 3 than at other analogous compounds.

Synthesis and characterization of novel platinum(IV) complexes with non-functionalized acetylated carbohydrates

[PtMe3(Me2CO)3]BF4 (1) reacts in acetone with 1,2,3,4-tetraacetyl-beta-D-glucopyranose (C2), pentaacetyl-alpha-D-glucopyranose (C3), pentaacetyl-beta-D-mannopyranose (C4) and pentaacetyl-beta-D-galactopyranose (C5) to give trimethyl(carbohydrate)platinum tetrafluoroborate complexes [PtMe3L]BF4 (2-5) (2, L=C2; 3, L=C3; 4, L=C4; 5, L=C5). The platinum-carbohydrate complexes were isolated as white, air and moisture sensitive powders in moderate to good yields (26-87%), and their identities were confirmed by microanalysis, 1H-, 13C- and 195Pt-NMR spectroscopy and ESI mass spectrometry. The coordination modes of the tridentately bound carbohydrate ligands (2, OH+Oring+Oacetyl; 3, Oring+Oether+Oacetyl; 4,5, Oring+Oether+Oether where Oring is the oxygen of a pyranose ring and Oacetyl/ether is the acetyl and ether oxygen of an acetoxy substituent, respectively) were established by evaluating the chemical shifts and the 2J(Pt,H) coupling constants of the methyl ligands and by 2D-NOE experiments. Evaluation of the 3J(H,H) coupling constants shows that the pyranose rings are present in their 4C1 conformation. The results show that carbohydrates without anchoring groups and even without hydroxyl groups can coordinate to the metal center only through very weak donors such as oxygen atoms of pyranose rings and acetoxy substituents.

Sugar interaction with metal ions. Crystal structure and FT-IR spectroscopic study of strontium galactarate mono-hydrate

The crystal structure of strontium galactarate mono-hydrate, Sr2+ x C6H8O8(2-) x H2O, Mr = 313.76, monoclinic, P2(1)/c, a = 10.268(2), b = 10.333(2), c = 10.194(2) A, beta = 117.87(3) degrees, lambda(Mo K alpha) = 0.71073 A, Z = 4, Dx = 2.180 Mg m(-3), V = 956.1(3) A3, mu = 5.676 mm(-1), F(000) = 624, T = 293(2) K, R = 0.0260 for 1690 observed reflections and 145 parameters refined, has been determined. The galactarate ion is centro-symmetrical in the crystal structure, although it contains independent half-ions. The Sr2+ ion is nine-coordinated (tricapped trigonal prism) with five Sr-O bonds from carboxylic groups, and four from hydroxyl groups. The water molecule does not take part in the coordination. Six hydrogen bonds are formed, three of them related to the water molecule. The spectroscopic evidence shows that the carboxylic acid dimers of the free acid dissociate. The asymmetric stretching vibrations of the anionic COO groups in the salt are observed at 1609 and 1548, and 1581 cm(-1), assigned to a mono-dentate and a tetra-dentate coordination, respectively. The symmetric stretching vibration is located at 1397 cm(-1). The hydroxyl groups of the galactarate skeleton take part in the metal-oxygen interaction, and the hydrogen-bonding network is rearranged upon sugar metalation.