Hyperfine interaction parameters and ground-state wavefunctions of vanadyl ion complexes

Using crystal field approach a theoretical estimate of the ground-state wavefunctions of vanadyl ion doped in various crystals have been made using ESR data and is found to bed _xy in our coordinate system with slight admixture of the excited states ,d _xz andd _yz. The hyperfine interaction parameterP and Fermi contact coupling parameterK have also been estimated for these vanadyl-doped crystals. Results agree with similar studies made earlier.     

Ion-Exchange Properties of Alkali-Metal Redox-Intercalated Vanadyl Phosphate

Ion exchange of alkali metals in M_xVOPO₄·yH₂O (M=H, Na, K, Rb, Cs) is reported. The role of valence, size, and affinity of the cations in the exchange process is discussed. The interlayer distance in the H_1-xK_xVOPO₄·yH₂O system is discussed in terms of finite layer rigidity theory. Different behavior is observed for K_xNa_1-xVOPO₄·yH₂O dependening on the starting compound used. When potassium in KVOPO₄·H₂O is exchanged for Na⁺, one phase compound is formed. In contrast, K_xNa_1-xVOPO₄·yH₂O formed from NaVOPO₄·H₂O and K⁺ is a multiphase system. Ion exchange does not proceed when exchanging ions differ distinctly from each other in size, e.g., sodium and cesium.     

A novel vanadyl selenite templated by organic salt: [(VO)(H2O)2(SeO3)]2[(H2pipe)SO4]

The title compound [(VO)(H₂O)₂(SeO₃)]₂[(H₂pipe)SO₄] was synthesized under hydrothermal condition with VOSO₄, piperazidine (pipe), and SeO₂, and its crystal structure was established using single-crystal X-ray diffraction method. The title compound was characterized with IRFluorescence. The crystal data: P-1 (No. 2), a = 8.633(2) Å, b= 9.223(2) Å, c= 12.508(3) Å, =109.28(3)°, =90.42(3)°, = 107.79(3)°, Mr = 644.08, V=888.5(3) ų, Z=2, Dc = 2.407 g cm^–3, =5.350 mm^–1, F(000)=632. The structure of the title compound consists of an infinite neutral ladder chain, which is built up from VO₆ octahedral and SeO₃ pyramidal units sharing vertices, and organic salt. The biprotonized pipe (piperazidine) and SO₄ ^2– interact with one another and the inorganic chain through strong hydrogen bonds N–H···O or O–H···O to give a 3D structure. Hydrogen bonds play a role of stabilization structure.     

Intercalation of 1-Alkanol Binary Mixtures into the Layered Structure of Vanadyl Phosphate

Mixed intercalates VOPO4.C2H5 OH.C4 H9OH, VOPO4.C3H7 OH.C5H11OH, VOPO4.C3H7 OH.C6H13OH and VOPO4.C4H9 OH.C6H13OH have been prepared by reaction of polycrystalline vanadyl phosphate dihydrate with liquid mixtures of the 1-alkanols in a microwave field. The same mixed layer-type complexes were also obtained as intermediary products of exchange reactions consisting in substitution of one alkanol bound in the solid intercalate by another alkanol introduced in the form of vapour. The composition of products has been determined, and the basal spacing of all the mixed layer-type complexes prepared has been found by diffraction. A structural principle is suggested which governs the depositing of two kinds of 1-alkanol molecules (differing in the lengths of their aliphatic chains) while acting as guests in the layered structure of vanadyl phosphate.     

Multi-electron transfer process of vanadyl complexes for oxidative polymerization of diphenyl disulfide

Oligo(p-phenylene sulfide) is synthesized by oxidative polymerization of diphenyl disulfide with oxygen catalyzed by vanadyl acetylacetonate under strongly acidic conditions. The mechanistic studies reveal that the redox cycles of the vanadyl complexes give rise to catalysis through a two-electron transfer between diphenyl disulfide and molecular oxygen. The VO catalysts act as an excellent electron mediator to bridge a 1.0 V potential gap between the oxidation potential of disulfides and the reduction potential of oxygen. The VO-catalyzed oxygen-oxidative polymerization provides pure oligo(pphenylene sulfide)s containing an S–S bond. The polymeric product is of low molecular weight due to the insolubility under these conditions. (N,N′-ethylenebis(salicylideneaminato))oxovanadium-(IV), VO(salen), was used as an inert model compound to elucidate the redox chemistry of the vanadium complex. VO(salen) reacts with trifluoromethanesulfonic acid (CF₃SO₃H) or triphenylmethyl tetrafluoroborate (?₃C(BF₄)) to form a deoxygenated complex, V^IV(salen)²⁺, and a μ-oxodinuclear complex, [(salen)VOV(salen)]X₂, (X = CF₃SO₃^? or BF₄^?). The dimerization of VO(salen) is initiated by deoxygenation to produce V(salen)²⁺ which enters into an equilibrium with a second VO(salen) complex to produce the μ-oxo dimer. The two-electron transfer of the μ-oxo dinuclear vanadium complex is elucidated.     

Intercalates of Vanadyl Phosphate with Aliphatic Nitriles

Intercalates of vanadyl phosphate with aliphatic nitriles (acetonitrile, propionitrile, butyronitrile, valeronitrile and hexanenitrile) were prepared and characterized by X-ray powder diffraction, thermogravimetric analysis, IR and Raman spectroscopies. The basal spacings of all the intercalates prepared are practically identical. The nitrile intercalates (except acetonitrile) contain one nitrile molecule per formula unit. The nitrile molecules are anchored to the host layers by an N–V donor-acceptor bond and their aliphatic chains are parallel to the host layers. The acetonitrile intercalate contains two guest molecules per formula unit. Only half of them can be bonded to the vanadium atom, the second half is probably anchored by van der Waals interaction. The intercalates prepared are moisture-sensitive and the guest molecules are easily replaced by water molecules.     

Intercalation of Dimethyl Carbonate, Diethyl Carbonate and Ethylene Carbonate into Vanadyl Phosphate

Intercalation compounds of vanadyl phosphate with dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethylene carbonate (EC) were prepared from VOPO₄·2C₂H₅OH intercalate by a molecular exchange. The intercalates prepared were characterized using powder X-ray diffraction and thermogravimetric analysis. The EC intercalate is stable at ambient conditions, whereas the DMC and DEC intercalates transform to vanadyl phosphate dihydrate. Infrared spectra indicate that carbonyl oxygens of the guest molecules are coordinated to the vanadium atoms of the host layers. The arrangement of the guest molecules in the interlayer space was proposed.     

Effects of Vanadyl Complexes with Acetylacetonate Derivatives on Non-Tumor and Tumor Cell Lines

Vanadium has a good therapeutic potential, as several biological effects, but few side effects, have been demonstrated. Evidence suggests that vanadium compounds could represent a new class of non-platinum, metal antitumor agents. In the present study, we aimed to characterize the antiproliferative activities of fluorescent vanadyl complexes with acetylacetonate derivates bearing asymmetric substitutions on the β-dicarbonyl moiety on different cell lines. The effects of fluorescent vanadyl complexes on proliferation and cell cycle modulation in different cell lines were detected by ATP content using the CellTiter-Glo Luminescent Assay and flow cytometry, respectively. Western blotting was performed to assess the modulation of mitogen-activated protein kinases (MAPKs) and relevant proteins. Confocal microscopy revealed that complexes were mainly localized in the cytoplasm, with a diffuse distribution, as in podocyte or a more aggregate conformation, as in the other cell lines. The effects of complexes on cell cycle were studied by cytofluorimetry and Western blot analysis, suggesting that the inhibition of proliferation could be correlated with a block in the G2/M phase of cell cycle and an increase in cdc2 phosphorylation. Complexes modulated mitogen-activated protein kinases (MAPKs) activation in a cell-dependent manner, but MAPK modulation can only partly explain the antiproliferative activity of these complexes. All together our results demonstrate that antiproliferative effects mediated by these compounds are cell type-dependent and involve the cdc2 and MAPKs pathway.     

NaVPO5晶体的水热合成与结构研究

通过在水热合成体系中加入还原剂,利用五价钒化合物成功地合成出纯相NaVPO₅晶体,并用电子顺磁共振和四圆衍射对其进行了表征.     

邻香草醛氧钒配合物的合成和晶体结构

钒是人体所必需的微量元素,钒化合物是新一代潜在的抗糖尿病药物。我们合成了邻香草醛氧钒配合物[VO(o-van)2(H2O)],并通过红外光谱,元素分析和X-射线单晶衍射等手段确定了其结构。