Optical and electron spin resonance spectra of the 11-tungstovanado(IV)phosphate anion. Heteropoly blue analog

Smith, Dorothy P.; So, Hyunsoo; Bender, Joseph; Pope, Michael T.

doi:10.1021/ic50121a040

Cited by 47 publications

(25 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At room temperature the unpaired electron will be interacting equally with the two adjacent vanadium nuclei ( 51 V, I = 7/2, 100%) by a thermally activated hopping process 26 and this leads to 15 line pattern in the EPR spectrum at room temperature. The EPR spectrum of the reduction product obtained in the present study is similar to the EPR spectrum of one electron reduced HPB prepared by controlled potential electrolysis [26][27][28] …”

Section: Products Of the Reactionsupporting

confidence: 59%

Studies on electron transfer reactions of Keggin-type mixed addenda heteropolytungstovanadophosphates with NADH

Sami

Rajasekaran

2009

J Chem Sci

View full text Add to dashboard Cite

The coenzyme nicotinamide adenine dinucleotide (NADH) undergoes facile electron transfer reaction with vanadium (V) substituted Keggin-type heteropolyanions (HPA) [PV V W 11 O 40 ] 4-(PV 1 ) and [PV V 2 W 10 O 40 ] 5-(PV 2 ) in aqueous phosphate buffer of pH 6 at ambient temperature. Electrochemical and optical studies show that the stoichiometry of the reaction is 1 : 2 (NADH : HPA). EPR and optical studies show that HPA act as one electron acceptor and the products of electron transfer reactions are one electron reduced heteropoly blues (HPB), viz. [PV IV W 11 O 40 ] 5-and [PV IV V V W 10 O 40 ] 6-.Oxygraph measurements show that there is no uptake of molecular oxygen during the course of reaction. The reaction proceeds through multi-step electron-proton-electron transfer mechanism, with rate limiting initial one electron transfer from NADH to HPA by outer sphere electron transfer process. Bimolecular rate constant for electron transfer reaction between NADH and PV 2 in phosphate buffer of pH = 6 has been determined spectrophotometrically.

show abstract

Section: Products Of the Reactionsupporting

confidence: 59%

Studies on electron transfer reactions of Keggin-type mixed addenda heteropolytungstovanadophosphates with NADH

Sami

Rajasekaran

2009

J Chem Sci

View full text Add to dashboard Cite

show abstract

“…1d). By comparison with the UV-visible spectrum reported in the literature [35], the reduction product of HPA1 was identified as the oneelectron reduced heteropoly blue, ½PV IV W 11 O 40 4À , which shows a band at 500 nm due toV(IV) ! W(VI) intervalance charge transfer band (IVCT) and a shoulder at 650 nm (d-d transition of V(IV)).…”

Section: Resultsmentioning

confidence: 89%

Vanadium(V)-substituted Keggin-type heteropolyoxotungstophosphates as electron transfer and antimicrobial agents: oxidation of glutathione and sensitization of MRSA towards β-lactam antibiotics

Sami¹,

Anand²,

Premanathan³

et al. 2010

Transition Met Chem

View full text Add to dashboard Cite

Glutathione (GSH) undergoes facile electron transfer with vanadium(V)-substituted Keggin-type heteropolyoxometalates, ½PV V W 11 O 40 4À (HPA1) and ½PV V -V V W 10 O 40 5À (HPA2). The kinetics of these reactions have been investigated in phthalate buffers spectrophotometrically at 25°C in aqueous medium. One mole of HPA1 consumes one mole of GSH and the product is the oneelectron reduced heteropoly blue, ½PV IV W 11 O 40 5À . But in the GSH-HPA2 reaction, one mole of HPA2 consumes two moles of GSH and gives the two-electron reduced heteropoly blue ½PV IV V IV W 10 O 40 7À . Both reactions show overall third-order kinetics. At constant pH, the order with respect to both [HPA] species is one and order with respect to [GSH] is two. At constant [GSH], the rate shows inverse dependence on [H ? ], suggesting participation of the deprotonated thiol group of GSH in the reaction. A suitable mechanism has been proposed and a rate law for the title reaction is derived. The antimicrobial activities of HPA1, HPA2 and ½PV V V V V V W 9 O 40 6À (HPA3) against MRSA were tested in vitro in combination with vancomycin and penicillin G. The HPAs sensitize MRSA towards penicillin G.

show abstract

“…160 mT, with the outermost hyperfine lines being clearly resolved. This subspectrum is characteristic of a monovanadium(IV) with its axial symmetry where the parallel hyperfine component, A ∥ , is larger than perpendicular component, A ⊥ (see below) . There are at least three components that comprise the EPR spectrum of 4 , with the broad lines on the isotropic component and a miniscule contribution from two axial signals identical to that seen in 2 .…”

Section: Resultsmentioning

confidence: 99%

“…However, any increase in bond covalency provided by the larger, more diffuse 4d and 5d orbitals of Mo and W ions would also reduce the 51 V hyperfine interaction as spin density is filtered away from the V IV ion. However, the A ‐values are invariant, therefore the higher g z value for molybdovanadates compared with tungstovanadates is a consequence of low‐energy charge‐transfer excited states that mix with the ground state via spin‐orbit coupling . Although tungsten has a larger spin‐orbit coupling constant, the heteronuclear intervalence charge transfer (IVCT) transition, V IV →W VI is typically above 20 000 cm −1 .…”

Section: Resultsmentioning

confidence: 99%

Directed Self‐Assembly, Symmetry Breaking, and Electronic Modulation of Metal Oxide Clusters by Pyramidal Heteroanions

Sartzi

Long

Sproules

et al. 2018

Chemistry A European J

View full text Add to dashboard Cite

Mixed valence/metal polyoxometalate (POM) clusters are one of the most interesting host species because they show the ability to incorporate a wide range of heteroatoms of various charges and geometries. We report herein the incorporation of pyramidal EO heteroanions (E=PH, S, Se, Te) that are responsible not only for directing the templated assembly of a family of mixed-metal POMs but also for the symmetry-breaking of the traditional Dawson architecture and modulation of the electronic characteristics of the cluster's shell. The isolated family of POMs consists of four members: (Me NH ) Na [Mo V O (HPO )]⋅MeOH⋅5 H O (1), (NH ) [Mo V O (SO )]⋅12 H O (2), K [Mo V O (SeO )] ⋅31 H O (3), and (Me NH ) Na[Mo V O (TeO )]⋅15 H O (4), and were characterized by X-ray structural analysis, electrospray ionization mass spectrometry (ESI-MS), thermogravimetric analysis (TGA), UV/Vis, FTIR, elemental analysis, flame atomic absorption spectroscopy (FAAS), and inductively coupled plasma optical emission spectroscopy (ICP-OES). Cyclic voltammetry (CV) and electron paramagnetic resonance (EPR) spectroscopic studies in concert with density functional theoretical (DFT) calculations have been used to elucidate the effect of the heteroatom on the electronic properties of the cluster.

show abstract

Optical and electron spin resonance spectra of the 11-tungstovanado(IV)phosphate anion. Heteropoly blue analog

Cited by 47 publications

References 1 publication

Studies on electron transfer reactions of Keggin-type mixed addenda heteropolytungstovanadophosphates with NADH

Studies on electron transfer reactions of Keggin-type mixed addenda heteropolytungstovanadophosphates with NADH

Vanadium(V)-substituted Keggin-type heteropolyoxotungstophosphates as electron transfer and antimicrobial agents: oxidation of glutathione and sensitization of MRSA towards β-lactam antibiotics

Directed Self‐Assembly, Symmetry Breaking, and Electronic Modulation of Metal Oxide Clusters by Pyramidal Heteroanions

Contact Info

Product

Resources

About