The unusual ascidian ability to accumulate high levels of vanadium ions at concentrations of up to 350 mM, a 10(7)-fold increase over that found in seawater, has been attracting interdisciplinary attention for a century. Accumulated V(V) is finally reduced to V(III) via V(IV) in ascidian vanadocytes. Reducing agents must therefore participate in the reduction. Previously, we identified a vanadi...

One of the major sources of lost capacity in all-vanadium redox flow batteries (VRFBs) is the undesired transport (usually called crossover) of water and vanadium ions through the ion-exchange membrane. In this work, an experimental assessment of the impact of ion-exchange membrane properties on vanadium ion crossover and capacity decay of VRFBs has been performed. Two types of cationic membran...

21 vanadium bis-phenolate benzimidazolyidene complexes spanning three oxidation states have been investigated. Special emphasis is thereby laid on their salt metathesis reactivity and the accessibility of +IV state by reductive or oxidative routes, starting from vanadium(V) vanadium(III) respectively. While route highly depended reducing agent material used, gives clean access to vanadium(IV) d...

The stoichiometry and thermodynamic stability of vanadium(IV/V) complexes of Triapine and two related α(N)-heterocyclic thiosemicarbazones (TSCs) with potential antitumor activity have been determined by pH-potentiometry, EPR and (51)V NMR spectroscopy in 30% (w/w) dimethyl sulfoxide/water solvent mixtures. In all cases, mono-ligand complexes in different protonation states were identified. Dim...

An aqueous deposition process for V(6)O(13) films is developed whereby the vanadium oxidation state is continuously controlled throughout the entire process. In the precursor stage, a controlled wet chemical reduction of the vanadium(V) source with oxalic acid is achieved and monitored by (51)Vanadium Nuclear Magnetic Resonance ((51)V-NMR) and Ultraviolet-Visible (UV-Vis) spectroscopy. The resu...

The reaction of vanadium(III) trichloride with tert-butylphosphonic acid (t-BuPO3H2) in the presence of 1,10-phenanthroline/2,2'-bipyridine as an ancillary ligand in acetonitrile at room temperature afforded two dinuclear dicationic vanadium(IV) complexes [(VO)2(phen)2{t-BuPO2(OH)}2(OH2)2]·2Cl [1] and [(VO)2(bipy)2{t-BuPO2(OH)}2(OH2)2]·2Cl [2]. On the other hand, when the reaction was carried o...

Isostructural vanadium, niobium and tantalum complexes of bis(3,5-di-tert-butyl-2-phenol)amine ([ONO]H3), were prepared and characterized to evaluate the impact of the metal ion on redox-activity of the ligand platform. New vanadium and niobium complexes with the general formula, [ONO]MCl2L (M = V, L = THF, 1-V; M = Nb, L = Et2O, 1-Nb) were prepared and structurally analysed by X-ray crystallog...

The present results show that indeed the structural data allow us to decide which vanadium centers must be considered formally as + 5 and which as + 4, at least with respect to the limit of strong localization. In fact, if the V3 and V3a centers were to be considered as vanadium(Iv), or as intermediates between vanadium(rv) and vanadium(v), they would be involved in several strong p o x 0 bridg...