Mixed-valence Vanadium Research Articles

Reaction of Ph2C(X)(CO2H) (X = OH, NH2) with [VO(OR)3] (R = Et, nPr): structure, magnetic susceptibility and ROP capability.

Reaction of [VO(OR)3] (R = Et, nPr) with 2,2'-diphenylglycine afforded the alkoxide-bridged dimers {[VO(OR)(μ-OR)][Ph2C(NH2)(CO2)]}2, whereas use of benzilic acid, in the presence of alkali metals, afforded 16-membered metallocycles {V8(O)4M(OR)8[Ph2C(OH)(CO2)]12} (M = <1 Na, K). For the ring systems, magnetic susceptibility data is consistent with mixed-valence vanadium with an average oxidation state of 3.5. The dimer and ring systems are capable of the ring opening polymerisation (ROP) of ε-caprolactone under N2, air, or as melts affording mostly low to medium molecular weight cyclic and linear products.

Optimized V‐Doped Defective TiO2/α‐(Fe2O3)1‐x(Cr2O3)x Heterojunctions for Photo‐Assisted Supercapacitor Devices: Insights on the Materials Integrity and Dual Conversion‐Storage Mechanism

AbstractEnergy conversion and storage integrated power units suffer from multiple engineering issues. Replacing two devices (solar cell and supercapacitor assembly) with one device (photo‐enhanced supercapacitor‐ PSC) requires materials with emerged dual solar‐electrochemical storage attributes. Herein, a propitious approach is developed to fabricate all visible light‐enhanced semisolid flexible PCS. Nanoflakes‐based p‐n junction α‐(Fe2O3)1‐x(Cr2O3)x photocathode is synthesized directly on industrial waste stainless steel mesh (316L‐SS). Alongside, three TiO2‐based electrodes are utilized as positive photoactive electrodes. Tuning the optical properties of TiO2 is displayed via doping with mixed valence vanadium (V4+/V5+) together with thermal hydrogen annealing. This is revealed via the reduction of the bandgap energy from 2.89 to 2.15 eV, which can be ascribed to the induced oxygen vacancies. The device can sustain up to 1.6 V potential window with 91% stability after 350 successive charge/discharge cycles with the possibility of performance regeneration to its 100% retention. An illustration of the photo‐storage mechanism is proposed based on the X–ray photoelectron spectroscopy, X–ray crystallography, and band position/alignment results. Quasi‐reversible water splitting/formation is concluded as the main storage mechanism in the semisolid state electrolyte under illumination conditions.

Octa- and Tetradecanuclear Mixed-Valent Vanadium(III/IV) Malates with Triazoles: Gas Adsorptions, Chiral Interface Recognition, and In Situ Decarboxylation.

Spontaneous resolution has been found for a pair of cage-like octanuclear mixed-valent vanadium(III/IV) malate enantiomers [Δ-VIII4VIV4O5(R-mal)6(Hdatrz)6]·44.5H2O (ΔR-1) and [Λ-VIII4VIV4O5(S-mal)6(Hdatrz)6]·38.5H2O (ΛS-1, H3mal = malic acid; Hdatrz = 3,5-diamino-1,2,4-triazole). Their racemic reduced product K7[VIII5VIV3O5(R,S-mal)6(trz)6]·17H2O (2) and tetradecanuclear species K11[VIII3VIV11O11(R,S-mal)12(atrz)6]·45.5H2O (3) (Htrz = 1,2,3-triazole, Hatrz = 3-amino-1,2,4-triazole) have also been obtained. In situ decarboxylation happens for 3-amino-1,2,4-triazole-5-carboxylic acid (H2atrzc) to yield 3-amino-1,2,4-triazole under hydrothermal conditions. Both 1 and 2 show an interesting bicapped-triangular-prismatic {V8O5(mal)6} building block, which further decorates symmetrically with three [VIV2O2(R,S-mal)2]2- units to construct a pinwheel-like {V14}-cluster, 3. Bond valence calculation sum (BVS) analyses manifest that the oxidation states of bicapped V atoms are +3 in 1-3, while the other V atoms in the {V6O5} core are ambiguous between +3 and +4 states with strong electron delocalization. Intriguingly, the triple helical chains in 1 associate in parallel to generate an amine-functionalized chiral polyoxovanadate (POV)-based supramolecular open-framework. The diameter of the interior channel is 13.6 Å, showing preferential adsorption of CO2 over gases N2, H2, and CH4. Importantly, homochiral framework ΔR-1 is capable of performing chiral interface recognition for R-1,3-butanediol (R-BDO) through host-guest interactions, as confirmed by the structural analysis of the host-guest complex ΔR-1·3(R-BDO). There are six R-BDO molecules in the channel of ΔR-1.

Glutathione-Activated In Situ Transformation of Nanosized Vanadium Oxides for Postoperative Precision Tumor Theranostics

It is highly desirable to precisely observe the real-time location of residual tumor tissues after surgery without interference and further realize postoperative tumor-specific therapy. Herein, glutathione (GSH)-activated in situ transformation of nanosized vanadium (V) oxides (V2O5) to mixed valence vanadium oxides (VOx) was carried out to realize postoperative precision tumor theranostics. Especially, hyaluronic acid-hybridized V2O5 nanoparticles (HA@V2O5 NPs) were in-situ-transformed to HA-hybridized VOx NPs via the reduction of GSH overexpressed in residual tumor. The transformation of V2O5 to VOx could not only generate near-infrared absorption but also endow VOx with the ability to catalyze hydrogen peroxide to produce hydroxyl radicals. By combining receptor-mediated targeting (RMT) toward tumor cells of HA and GSH-activated in situ transformation, HA@V2O5 NPs could be applied to precisely determine the location of residual tumor tissues in real time via photoacoustic (PA) observation without interference of inflammation after surgery and further realize postoperative tumor-specific photothermal/chemodynamic eradication of them. Therefore, the present work opens the way to utilize the combination strategy of RMT and GSH-activated in situ transformation of inorganic metal oxides to meet the need of postoperative precision tumor theranostics.

MXene Aerogel Derived Ultra-Active Vanadia Catalyst for Selective Conversion of Sustainable Alcohols to Base Chemicals.

Selective oxidation reactions are an important class of the current chemical industry and will be highly important for future sustainable chemical production. Especially, the selective oxidation of primary alcohols is expected to be of high future interest, as alcohols can be obtained on technical scales from biomass fermentation. The oxidation of primary alcohols produces aldehydes, which are important intermediates. While selective methanol oxidation is industrially established, the commercial catalyst suffers from deactivation. Ethanol selective oxidation is not commercialized but would give access to sustainable acetaldehyde production when using renewable ethanol. In this work, it is shown that employing 2D MXenes as building blocks allows one to design a nanostructured oxide catalyst composed of mixed valence vanadium oxides, which outperforms on both reactions known materials by nearly an order of magnitude in activity, while showing high selectivity and stability. The study shows that the synthesis route employing 2D materials is key to obtain these attractive catalysts. V4C3Tx MXene structured as an aerogel precursor needs to be employed and mildly oxidized in an alcohol and oxygen atmosphere to result in the aspired nanostructured catalyst composed of mixed valence VO2, V6O13, and V3O7. Very likely, the bulk stable reduced valence state of the material together coupled with the nanorod arrangement allows for unprecedented oxygen mobility as well as active sites and results in an ultra-active catalyst.

Ionic Liquid-Stabilizing Vanadium Oxo-Cluster Catalysts for One-Step Selective Oxidative Cleavage of β–O–4 Lignin Model Compounds

An easily accessible and efficient catalyst is highly promising for the cleavage of the C–C bond and C–O bond of β–O–4 lignin model compounds. In this work, ionic liquid [Bim][Pic] (Bim = 1-butyl imidazolium, Pic = picolinate anion)-stabilizing vanadium oxo-cluster catalysts were constructed conveniently for selective aerobic oxidation to cleave the β–O–4 linkages into phenols, eaters and acids. The as-synthesized vanadium oxo-cluster catalysts Bim-V-n (n = 1–3) were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), electron paramagnetic resonance (EPR), mass spectrometry (MS), and elemental analysis. The vanadium in the catalyst exists stably in a mixed-valence state of V4+ and V5+. Molecular oxygen was activated through the mutual transformation of V4+ and V5+ to form superoxide free radicals, which were captured by the EPR spectrum. Especially, Bim-V-2 afforded superior catalytic activity under aerobic conditions (10 h, 120 °C). The highly reversible interconversion of V4+ and V5+ species in vanadium oxo-cluster allowed the coexistence of the mixed-valence vanadium species, which was responsible for oxidizing β–O–4 alcohols to β–O–4 ketones. Moreover, superoxide free radicals can facilitate the cleavage of C–C and C–O bonds in β–O–4 ketones. Especially, 1-butyl imidazolium also played a positive role in the cleavage of C–O bonds by the action of the cation protons. No appreciable loss of catalytic activity was observed, and the catalyst could be recovered and reused up to five times, reflecting the excellent recyclability of the present vanadium oxo-cluster catalysts. The catalytic system can be extended for the cleavage of the C–C bond and C–O bond of β–O–4 of the other lignin model compounds, and the reaction could still be completed efficiently. This provides a new perspective for the selective aerobic oxidation of β–O–4 lignin without co-catalysts.

Clean preparation of mixed trivalent and quadrivalent vanadium electrolyte for vanadium redox flow batteries by catalytic reduction with hydrogen

The vanadium redox flow battery (VRFB) is a promising technology for large-scale stationary energy storage systems. However, the high preparation cost of mixed valent vanadium electrolyte hinders the large-scale commercial application of VRFB. In this work, a simple, green and low-cost method is proposed to prepare the mixed valent vanadium electrolyte for VRFB. The clean hydrogen is chosen as the reducing agent to obtain trivalent vanadium ions from quadrivalent vanadium ions. The Pt/C material is used as the catalyst to accelerate the reduction rate at atmospheric pressure. The impurity-free mixed valent vanadium electrolyte, with a mean valence number of 3.5, prepared by the catalytic reduction process exhibits excellent battery performance with CE of 93% and EE of 85%. Furthermore, a catalytic reactor using Pt/C decorated graphite felt is designed and used to continuously produce the mixed valent vanadium electrolyte. According to the result of simple cost analysis, the proposed catalytic hydrogen reduction process can reduce theoretically the manufacturing cost by approximately 22.6% compared with the present industrial electrolytic process. As a consequence, the simple, clean and low-cost manufacture method of the mixed valent vanadium electrolyte exhibits remarkable competitiveness and promising potential for the practical production application of VRFB.

Photocatalytic Selective Oxidation of Toluene into Benzaldehyde on Mixed-Valence Vanadium Oxide V6O13 Catalyst with Density Functional Theory

Photocatalytic Selective Oxidation of Toluene into Benzaldehyde on Mixed-Valence Vanadium Oxide V6O13 Catalyst with Density Functional Theory

Proton-assisted mixed-valence vanadium oxides cathode with long-term stability for rechargeable aqueous zinc ion batteries

In this work, we developed a rGO assisted vanadium oxide xerogel (abbreviate as VOHG) as cathode material for rechargeable aqueous zinc ion batteries (RA-ZIBs). The VOHG cathode exhibits an ultra-high specific capacity of 625 mA h g−1 at current density of 0.1 A g−1, superior reversibility and a long cycle life with a coulombic efficiency of 100.0% after 10,000 cycles. The VOHG material has mixed valent vanadium ions V4+/V5+and a layer structure with interlayer water. The interlayer water acts as soft support for the VO6 octahedron, forming a large space in the layers for H+/Zn2+ intercalation, which improves the migration rate of Zn2+ due to its charge shielding effect. Protons can move quickly through the interlayer water network by Grotthuss proton transport mechanism. The application of the unique structure of VOHG makes zinc ions battery will be a promising candidate of energy storage device with high-capacity and long cycle stability.

Structural and magnetic characterization of mixed-valence vanadium (IV/V) complex with {(VO)2(µ‒O)}3+ core: Theoretical and experimental insights

Using deprotonated forms of tetradentate phenol amine ligands 2-((((1-methylbenzimidazol-2-yl)methyl)(pyridin-2-ylmethyl)amino)methyl)phenol (HL1), dinuclear vanadium(IV,V) complex of composition [(L1)2(VIVO)(µ-O)(VVO)](ClO4) (1) was synthesized and characterized by X–ray crystallography, UV–Vis, EPR and magnetic susceptibility measurements. Direct current (DC) variable-temperature magnetic susceptibility measurements on polycrystalline sample of 1 were carried out in the temperature range 1.8–300 K. Electron paramagnetic resonance and magnetic studies for 1 demonstrated the complete localization of the single 3d electron on one of vanadium ion and very weak antiferromagnetic interaction between the paramagnetic vanadium(IV) ions in the crystal lattice. The cyclic voltammogram observed with 1, revealed one oxidation process which is tentatively assigned to VIVVV/V2V. [(L1)2(VVO)2(µ-O)](ClO4)2 (2.2.5CH2Cl2) has been synthesized chemically from 1 and were thoroughly characterized by X–ray crystallography, UV–Vis, 51V NMR and IR measurements.

V6O13 nanosheets self-assembled into 3D hollow microflowers for long-life and high-rate Li-ion batteries

Among vanadium-based materials, V6O13 is considered to be an ideal cathode candidate material due to its high theoretical capacity and energy density. However, as mixed-valence vanadium oxide, it faces the challenge of controllable synthesis, and suffers unsatisfactory cycle performance due to the unstable structure. Constructing 3D micro/nano-structures is a very effective method to solve the above problems. Herein, we report a simple template-free solvothermal method to controllably synthesize 3D hollow microflowers structure formed by self-assembly of thin nanosheets. The growth mechanism of the hollow microflowers is revealed by changing the solvothermal reaction time and the content of ethylene glycol. As a cathode material for Li-ion batteries, the V6O13 hollow microflowers exhibit an initial discharge specific capacity of 326 mAh/g at a current density of 0.1 A/g. Even at a high current density of 1 A/g, the V6O13 hollow microflowers still deliver a discharge capacity of 183.2 mAh/g, and display high capacity retention of 75.6% after 500 cycles. The excellent electrochemical performance benefits from the unique advantages of 3D hollow microflowers structure, that is, large specific surface area, abundant mesopores, and robust structure. These results indicate that the V6O13 hollow microflowers have great potential as the long-life and high-rate cathode materials for the next generation of Li-ion batteries.

Monomeric (VO2+) and dimeric mixed valence (V2O33+) vanadium species at the surface of shape controlled TiO2 anatase nano crystals

Metal atoms and ions at well-defined anatase TiO2 crystals with exposed (101) and (001) facets represent a promising platform for fundamental studies in catalysis using model systems of high complexity for the development of novel catalytic systems exhibiting higher than usual activities. Herein, we report the geometric and electronic structures of supported paramagnetic vanadium catalysts obtained by reaction of VCl4 vapours with shape controlled anatase TiO2 supports with preferential (101) and (001) facets. Electron Paramagnetic Resonance (EPR) spectroscopy and Density Functional theory (DFT) calculations reveal the presence specific monomeric (VO2+) and dimeric mixed valence (V2O33+) species with molecular structures dependent on the TiO2 surface termination.

Proton-Assisted Mixed-Valence Vanadium Oxides Cathode with Long-Term Stability for Rechargeable Aqueous Zinc Ion Batteries

Proton-Assisted Mixed-Valence Vanadium Oxides Cathode with Long-Term Stability for Rechargeable Aqueous Zinc Ion Batteries

Controlled Aerosol-based Synthesis of Vanadium Oxides Nanoparticle for Supercapacitor Applications

BackgroundNanostructured mixed-valence vanadium oxides (VOx) are attractive as electrode materials for supercapacitor applications. Development of suitable synthetic and characterization methods for the fabrication of VOx nanostructures with controlled properties is of crucial importance. MethodsA continuous aerosol-based synthetic route with in-situ mobility size characterization is developed to fabricate VOx nanoparticles (NPs) in this study. Differential mobility analysis, X-ray diffractometry, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy are employed complementarily for material characterization. Cyclic voltammetry and galvanostatic charge-discharge tests are used to evaluate the specific capacitance and charge-discharge stability of the synthesized VOx NPs. Significant FindingsParticle size and mean valence of VOx NPs are controllable by adjusting the gas-phase synthetic conditions (atmosphere, temperature, gas flow rate). The specific capacitance of VOx NPs is shown to be proportional to the average valence of V, and the maximum specific capacitance (147.8 F/g) is achievable at an average oxidation state of 4.79 for vanadium. This work demonstrates a prototype study of fast and continuous production of VOx NPs with controlled material properties, showing promise in the tuning of cluster size and valence for the optimization of the corresponding supercapacitive performance.

A Force Field for a Manganese-Vanadium Water Oxidation Catalyst: Redox Potentials in Solution as Showcase

We present a molecular mechanics force field in AMBER format for the mixed-valence manganese vanadium oxide cluster [Mn4V4O17(OAc)3]3−—a synthetic analogue of the oxygen-evolving complex that catalyzes the water oxidation reaction in photosystem II—with parameter sets for two different oxidation states. Most force field parameters involving metal atoms have been newly parametrized and the harmonic terms refined using hybrid quantum mechanics/molecular mechanics reference simulations, although some parameters were adapted from pre-existing force fields of vanadate cages and manganese oxo dimers. The characteristic Jahn–Teller distortions of d4 MnIII ions in octahedral environments are recovered by the force field. As an application, the developed parameters have been used to calculate the redox potential of the [MnIIIMn3IV] ⇌ [Mn4IV]+e− half-reaction in acetonitrile by means of Marcus theory.

A mixed-valent vanadium oxide cathode with ultrahigh rate capability for aqueous zinc-ion batteries

The V10O24·nH2O cathode with a large interlayer spacing and stable structure exhibits superior rate capability and excellent cycling stability for aqueous zinc-ion batteries.

A new tunnel-type V4O9 cathode for high power density aqueous zinc ion batteries

A mixed-valence vanadium oxide V4O9 with a tunnel structure was synthesized as a cathode material for aqueous zinc ion batteries. A Zn//V4O9 battery displays high specific capacity and excellent rate performance.

Stable Structure and Electronic Structure for Mg(MgxVyNiz)O4 As Cathode Material for Magnesium Secondary Battery in Discharge Process Using First-Principle Calculation

1. Introduction Magnesium secondary batteries are expected to be applied as a next generation battery materials having higher volume energy density than lithium ion batteries. In our laboratory, we are conducting research and development on cathode materials for magnesium secondary batteries. In recent years, the spinel MgCo2O4 and MgCo1.5Mn0.5O4 in which part of Co is substituted with Mn have been synthesized and measured the battery characteristics of average structure1). From this previous study, it became clear that the Mg/Co cation mixing become decreasing and the first discharge capacity became increasing with the substitution of Mn atom. The first-principle calculation was also performed for the spinel MgCo2O4 and MgCo1.5Mn0.5O4 in pristine and discharge process and reported that the structure changed from a spinel structure to a rock salt structure during discharge2). From the first-principle calculation, it was found that the structure change of MgCo1.5Mn0.5O4 was remarkable because the bond between Mg and O was weakened especially by the influence of Mn. In our laboratory, we have also reported that spinel type Mg(MgxVyNiz)O4 with mixed valence vanadium ions as a host structure has better cycle characteristics than MgCo2O4 system3). However, the local structure in the charge / discharge process and the structural change when Mg is inserted have not been elucidated. The purpose of this study is to investigate the stable structure of Mg(MgxVyNiz)O4 at pristine and discharge process by using the first-principles calculation, and to clarify the mechanism of Mg insertion.2. Calculation method The stable structure of the spinel Mg(Mg0.31V1.69)O4 and Mg(Mg0.31V1.56Ni0.13)O4 inserted Mg atoms (shown as Mg1+y(Mg0.31V1.69)O4 and Mg1+y(Mg0.31V1.56Ni0.13)O4 (y = 0.125~0.75); y is equal to the amount of Mg atoms), were obtained by GGA+U method (VASP code) in discharge process. The cell size of the spinel Mg(Mg0.31V1.69)O4 and Mg(Mg0.31V1.56Ni0.13)O4 were (2×1×1).3. Results and discussion The stable structures of the spinel Mg(Mg0.31V1.69)O4 and Mg(Mg0.31V1.56Ni0.13)O4 at pristine obtained by the first-principle calculation are shown in Fig. 1. In previous study, it was reported that the 8a site was occupied by only Mg atom, and the 16d site was occupied by V, Mg and Ni atom from the average structure analysis measured by the synchrotron X-ray diffraction.3) Models are created based on the results of Rietveld analysis in this study. In both Fig. a-1) and b-1), Mg at 16d site tends to coordinate relatively close to each other in the crystal. It is found from b-1) that Ni also tends to coordinate to positions close to each other. Fig. 1.a-2) and b-2) show the stable structure at the discharge with y=0.25 of Mg inserted into the vacancy 16c site the spinel Mg(Mg0.31V1.69)O4 and Mg(Mg0.31V1.56Ni0.13)O4 at pristine, respectively. Green circles in Fig. 1 a-2) and b-2) are indicated the Mg inserted into the hole 16c site. The Mg before the structural relaxation is indicated by a black dotted circle, and the Mg moved after the structural relaxation is indicated by an arrow and a red circle in in Fig. 1 a-2) and b-2), respectively. As shown in Fig. a-2) and b-2), the structure of Mg become stable when it is inserted into the 16c site near Mg, which is mixed to the 16d site. The model in which the inserted Mg coordinated away from each other in the crystal has high total energy. In both a-2) and b-2), it is found that the Mg atoms at the 8a site near the inserted Mg have moved to the 16c site. When Mg are inserted into spinel Mg(Mg0.31V1.69)O4 and Mg(Mg0.31V1.56Ni0.13)O4, it becomes clear that the structural change to rocksalt is occurred around Mg at 16d site. This structural change during discharge is also observed in the spinel type MgCo2-xMnxO4 system. Since the distance between the nearest 8a site and 16c site is about 1.7 to 1.8 Å, it is considered that repulsion between cations occurs. On the lecture, we will show the electron density and discuss the electronic state in detail. Acknowledgement This work was partly supported by ALCA-SPRING Grant Number JPMJAL1301, Japan. We are deeply grateful for the cooperation.1) Y. Idemoto, Y. Mizutani, C. Ishibashi, N. Ishida and N. Kitamura, Electrochemistry 87, 220 (2019).2) C. Ishibashi, Y. Mizutani, N. Ishida, N. Kitamura, Y. Idemoto, Bull. Chem. Soc. Jpn. 92, 1950 (2019).3) Y. Idemoto, N. Kawakami, N. Ishida, N. Kitamura, Electrochemistry 87, 281 (2019). Figure 1

Natural Polyphenol-Vanadium Oxide Nanozymes for Synergistic Chemodynamic/Photothermal Therapy.

The selection of suitable nanozymes with easy synthesis, tumor specificity, multifunction, and high therapeutics is meaningful for tumor therapy. Herein, a facile one-step assembly approach was employed to successfully prepare a novel kind of natural polyphenol tannic acid (TA) hybrid with mixed valence vanadium oxide nanosheets (TA@VOx NSs). In this system, VOx is assembled with TA through metal-phenolic coordination interaction to both introduce superior peroxidase-like activity and high near infrared (NIR) absorption owing to partial reduction of vanadium from V5+ to V4+ . The presence of mixed valence vanadium oxide in TA@VOx NSs is proved to be the key for the catalytic reaction of hydrogen peroxide (H2 O2 ) to . OH, and the corresponding catalytic mechanism of H2 O2 by TA@VOx NSs is proposed. Benefitting from such peroxidase-like activity of TA@VOx NSs, the overproduced H2 O2 of the tumor microenvironment allows the realization of tumor-specific chemodynamic therapy (CDT). As a valid supplement to CDT, the NIR absorption enables TA@VOx NSs to have NIR light-mediated conversion ability for photothermal therapy (PTT) of cancers. Furthermore, in vitro and in vivo experiments confirmed that TA@VOx NSs can effectively inhibit the growth of tumors by synergistic CDT/PTT. These results offer a promising way to develop novel vanadium oxide-based nanozymes for enhanced synergistic tumor-specific treatment.

Isolated Mixed-Valence Iron Vanadium Malate and Its Metal Hydrates (M = Fe2+, Cu2+, Zn2+) with Reversible and Irreversible Adsorptions for Oxygen.

Isolated octanuclear iron-vanadium malate (NH4)3(CH3NH3)3[FeIII2VIV2VV4O11(mal)6]·7.5H2O (1; H3mal = malic acid) and its family of metal hydrates M'3n[MII(H2O)2]1.5n[FeIII2VIV2VV4O11(mal)6]n·xnH2O (2 or 2-Fe, M' = NH4+, M = Fe, x = 7.5; 3 or 3-Cu, M' = K+, M = Cu, x = 10; 4 or 4-Zn, M' = K+, M = Zn, x = 6.5) have been obtained by self-assembly in water. The cluster anion [Fe2V6O11(mal)6]6- (1a) shows an interesting iron bicapped-triangular-prismatic structure, which is bridged by M2+ hydrates (M = Fe, Cu, Zn) to construct isostructural metal organic frameworks (MOFs) 2-4. The mixed-valence vanadium systems in 1-4 were determined by theoretical bond valence calculations (BVS) and charge balance. The magnetic susceptibilities are further elucidated as high spin for Fe3+ in 1a and bridging Fe2+ in 2-Fe, respectively. A strong ferromagnetic interaction was also observed for 2-Fe at 3 K. 2-Fe, 3-Cu, and 4-Zn have similar hydrophilic channels with diameters of 6.8, 6.5, and 6.6 Å, respectively, which show obvious affinity for O2 in comparison with no adsorption of N2, H2, CO2, and CH4 at room temperature under different pressures. Moreover, 2-Fe and 4-Zn exhibit irreversible O2 absorptions, which may be attributed to charge transfer between O2 and open metal sites (OMSs) formed during vacuum heating pretreatment. UV-vis and EPR spectra show a change in electronic structure of 2-Fe after O2 adsorption. The reversible adsorption observed in 3-Cu suggests a weak interaction between O2 and Cu2+ due to the Jahn-Teller effect. The properties of gas adsorption provide an insight into the performances of small molecules in the channels constructed by synthetic octanuclear model compounds, which are related to the interactions between the gas substrate and the heterometal cluster in biology.