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An Inorganic Pac‐Man: Synthesis, structure and electrochemical studies of a heterometallic {YCoII3W} cluster sandwiched by two germanotungstates. Z Anorg Allg Chem 2022. [DOI: 10.1002/zaac.202200112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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2
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A tetrameric praseodymium substituted arsenotungstate (III) – Synthesis & characterization, electrochemistry, catalytic and its magnetic applications. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.115698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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3
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Understanding polyoxometalates as water oxidation catalysts through iron vs. cobalt reactivity. Chem Sci 2021; 12:8755-8766. [PMID: 34257875 PMCID: PMC8246111 DOI: 10.1039/d1sc01016f] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 05/13/2021] [Indexed: 01/08/2023] Open
Abstract
Cobalt polyoxometalates (Co-POMs) have emerged as promising water oxidation catalysts (WOCs), with the added advantage of their molecular nature despite being metal oxide fragments. In comparison with metal oxides, that do not offer well-defined active surfaces, POMs have a controlled, discrete structure that allows for precise correlations between experiment and computational analyses. Thus, beyond highly active WOCs, POMs are also model systems to gain deeper mechanistic understanding on the oxygen evolution reaction (OER). The tetracobalt Weakley sandwich [CoII 4(H2O)2(B-α-PW9O34)2]10- (Co4-WS) has been one of the most extensively studied. We have compared its activity with that of the iron analog [FeIII 4(H2O)2(B-α-PW9O34)2]6- (Fe4-WS) looking for the electronic effects determining their activity. Furthermore, the effect of POM nuclearity was also investigated by comparison with the iron- and cobalt-monosubstituted Keggin clusters. Electrocatalytic experiments employing solid state electrodes containing the POMs and the corresponding computational calculations demonstrate that CoII-POMs display better WOC activity than the FeIII derivatives. Moreover, the activity of POMs is less influenced by their nuclearity, thus Weakley sandwich moieties show slightly improved WOC characteristics than Keggin clusters. In good agreement with the experimental data, computational methods, including pK a values, confirm that the resting state for Fe-POMs in neutral media corresponds to the S1 (FeIII-OH) species. Overall, the proposed reaction mechanism for Fe4-WS is analogous to that found for Co4-WS, despite their electronic differences. The potential limiting step is a proton-coupled electron transfer event yielding the active S2 (FeIV[double bond, length as m-dash]O) species, which receives a water nucleophilic attack to form the O-O bond. The latter has activation energies slightly higher than those computed for the Co-POMs, in good agreement with experimental observations. These results provide new insights for the accurate understanding of the structure-reactivity relationships of polyoxometalates in particular, and or metal oxides in general, which are of utmost importance for the development of new bottom-up synthetic approaches to design efficient, robust and non-expensive earth-abundant water oxidation catalysts.
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Electrochemical Reduction of α-Amino Allenylphosphonates to α-Amino Allylphosphonates. European J Org Chem 2020. [DOI: 10.1002/ejoc.202000534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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5
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Syntheses, Crystal Structure, Electrocatalytic, and Magnetic Properties of the Monolanthanide-Containing Germanotungstates [Ln(H 2O) n GeW 11O 39] 5- (Ln = Dy, Er, n = 4,3). ACS OMEGA 2019; 4:21873-21882. [PMID: 31891065 PMCID: PMC6933596 DOI: 10.1021/acsomega.9b02846] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/18/2019] [Indexed: 06/10/2023]
Abstract
Two monolanthanide-containing polyanions based on monolacunary Keggin germanotungstates [Ln(H2O) n GeW11O39]5- (Ln = Dy, Er, n = 4,3) have been synthesized in simple one-pot synthetic procedure and compositionally characterized in solid state by single-crystal X-ray diffraction, powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and elemental analysis. Electronic absorption and emission spectra of the title compounds in solution were also studied. The [DyIII(H2O)4GeW11O39]5- Keggin POM exhibits a slow relaxation of magnetization. The cyclic voltammetry measurements and mass spectrometry were carried out to check the stability of the compounds in solution. Both polyanions prove efficient in the electrocatalytic reduction of nitrite. To our knowledge, this observation establishes the first example of electrocatalysis of nitrite reduction by all inorganic monolanthanide-containing germanotungstates family.
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Self‐Assembled Tetrameric Lanthanide‐Containing Germanotungstates [(Ln
2
GeW
10
O
38
)
4
(W
3
O
8
)(OH)
4
(H
2
O)
2
]
26−
: Syntheses, Crystal Structure, Photoluminescence and Electrochemical Properties. ChemistrySelect 2019. [DOI: 10.1002/slct.201903379] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Synthesis, structure and electrochemical characterization of an isopolytungstate (W4O16) held by MnII anchors within a superlacunary crown heteropolyanion {P8W48}. Dalton Trans 2019; 48:15545-15552. [DOI: 10.1039/c9dt02478f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The first example of an isopolyanion (W4O16) held by redox-active MnII anchors within an archetypal superlacunary heteropolyanion {P8W48}.
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8
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The role of interleukins in vitiligo: a systematic review. J Eur Acad Dermatol Venereol 2018; 32:2097-2111. [PMID: 29704266 DOI: 10.1111/jdv.15016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 03/20/2018] [Indexed: 12/30/2022]
Abstract
Vitiligo is a disorder of the skin that causes depigmentation and asymptomatic macules whose exact cause is still unclear. Although its aetiology is not fully elucidated, the main theory of its pathomechanism is that it is associated with the autoimmune process. There is few summarized information about the role of inflammatory mediators, as interleukins, in vitiligo, so our aim was to present a systematic review of the role of interleukins in vitiligo, focusing on interleukins. In this review, we included all studies assessing interleukin levels in vitiligo patients conducted up to June 2017. Quality assessment of these studies was performed using the Newcastle-Ottawa Scale (NOS). The interleukins mainly involved were IL-2, IL-4, IL-6, IL-10 and IL-17. The studies highlight the crucial role of IL-17 in the onset and progression of the disease, and its synergistic action with IL-2, IL-6 and IL-33. Dysregulated levels of the interleukins were also correlated with the stage of disease, the affected skin surface area, and indicated as the main factor for lymphocyte infiltration found in depigmented regions. These findings illustrate the growing need for new therapies targeting vitiligo and further research into the role of interleukins as an area of particular interest.
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Two New Sandwich-Type Manganese {Mn5}-Substituted Polyoxotungstates: Syntheses, Crystal Structures, Electrochemistry, and Magnetic Properties. Inorg Chem 2017; 56:8759-8767. [DOI: 10.1021/acs.inorgchem.6b02994] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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10
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One-Electron Oxidation of Methionine-Containing Dipeptides of Reverse Sequence: Sulfur versus Sulfoxide Characterized by IRMPD Spectroscopy and Static and Dynamics DFT Simulations. J Phys Chem B 2017; 121:2083-2094. [DOI: 10.1021/acs.jpcb.6b12638] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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11
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Synthesis, Structure, and Magnetic Electrochemical Properties of a Family of Tungstoarsenates Containing Just Co II Centers or Both Co II and Fe III Centers. Inorg Chem 2017; 56:1999-2012. [PMID: 28177256 DOI: 10.1021/acs.inorgchem.6b02593] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The three polyoxotungstates [(NaOH2)2CoII2(As2W15O56)2]18- (1), [(NaOH2)(CoIIOH2)CoII2(As2W15O56)2]17- (2), and [(CoIIOH2)2CoII2(As2W15O56)2]16- (3) have been prepared in aqueous solution upon mixing cobalt(II) salts with the ligand [As2W15O56]12-. The reaction of 1 or 2 with the Fe3+ ion leads invariably to the same species [(FeIIIOH2)(CoIIOH2)CoII2(As2W15O56)2]15- (4) possessing three cobalt atoms and a single iron atom. However, if the Fe-containing homologue of compound 1, that is, the polyoxotungstate [(NaOH2)2FeIII2(As2W15O56)2]16- (5), is employed instead to react with the Co2+ ion, the species [(CoIIOH2)2FeIII2(As2W15O56)2]14- (6) is obtained, having two cobalt atoms and two iron atoms. The compounds 1, 2, 3, 4, and 6 are described for the first time and have been characterized by several physicochemical methods such as FTIR, UV-visible, ATG, and elemental analysis. Structural analysis by single-crystal X-ray diffraction has been carried out with compounds 2 (monoclinic space group P21/c, a = 17.0622(5) Å, b = 15.0828(4) Å, c = 32.0872(8) Å, β = 91.170(1)°, and Z = 2) and 3 (triclinic space group P1̅, a = 13.6137(7) Å, b = 13.8836(8) Å, c = 22.9276(6) Å, α = 89.906(3)°, β = 78.356(2)°, γ = 61.451(2)°, and Z = 1). Electrochemical studies undertaken with all the above-mentioned compounds and some of their homologues shed light on the influence of the chemical composition on their electrocatalytic properties toward substrates such as the nitrite ion and dioxygen. Magnetic measurements evidence anisotropic ferromagnetic interactions between Co2+ ions and antiferromagnetic interactions between Fe3+ ions. The nature and the strength of the Co2+-Fe3+ interactions depend on the relative orientations of their 3d orbitals. The effective magnetic moment of the Co2+ ions varies with the temperature and with the distortion of the octahedral sites in which they are located.
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Methionine one-electron oxidation: Coherent contributions from radiolysis, IRMPD spectroscopy, DFT calculations and electrochemistry. Radiat Phys Chem Oxf Engl 1993 2016. [DOI: 10.1016/j.radphyschem.2016.05.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Cr III-Substituted Heteropoly-16-Tungstates [Cr III2(B-β-X IVW 8O 31) 2] 14- (X = Si, Ge): Magnetic, Biological, and Electrochemical Studies. Inorg Chem 2016; 55:10936-10946. [PMID: 27768287 DOI: 10.1021/acs.inorgchem.6b01458] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The dichromium(III)-containing heteropoly-16-tungstates [CrIII2(B-β-SiIVW8O31)2]14- (1) and [CrIII2(B-β-GeIVW8O31)2]14- (2) were prepared via a one-pot reaction of the composing elements in aqueous, basic medium. Polyanions 1 and 2 represent the first examples of CrIII-containing heteropolytungstates comprising the octatungstate unit {XW8O31} (X = Si, Ge). Magnetic studies demonstrated that, in the solid state, the two polyanions exhibit a weak antiferromagnetic interaction between the two CrIII centers with J = -3.5 ± 0.5 cm-1, with no long-range ordering down to 1.8 K. The ground-state spin of polyanions 1 and 2 was thus deduced to be 0, but the detection of a complex set of EPR signals implies that there are thermally accessible excited states containing unpaired spins resulting from the two S = 3/2 CrIII ions. A comprehensive electrochemistry study on 1 and 2 in solution was performed, and biological tests showed that both polyanions display significant antidiabetic and anticancer activities.
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Preparation of α1- and α2-isomers of mono-Ru-substituted Dawson-type phosphotungstates with an aqua ligand and comparison of their redox potentials, catalytic activities, and thermal stabilities with Keggin-type derivatives. Dalton Trans 2016; 45:3715-26. [PMID: 26672976 DOI: 10.1039/c5dt04219d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Both the α1- and the α2-isomers of mono-ruthenium (Ru)-substituted Dawson-type phosphotungstates with terminal aqua ligands, [α1-P2W17O61Ru(III)(H2O)](7-) (α1-RuH2O) and [α2-P2W17O61Ru(III)(H2O)](7-) (α2-RuH2O), were prepared in pure form by cleavage of the Ru-S bond of the corresponding DMSO derivatives, [α1-P2W17O61Ru(DMSO)](8-) (α1-RuDMSO) and [α2-P2W17O61Ru(DMSO)](8-) (α2-RuDMSO), respectively. Redox studies indicated that α1-RuH2O and α2-RuH2O show proton-coupled electron transfer (PCET), and the Ru(III)(H2O) species was reversibly reduced to Ru(II)(H2O) species and oxidized to Ru(IV)([double bond, length as m-dash]O) species and further to Ru(V)([double bond, length as m-dash]O) species in aqueous solution depending on the pH. Their redox potentials and thermal stabilities were compared with those of the corresponding α-Keggin-type derivatives ([α-XW11O39Ru(H2O)](n-); X = Si(4+) (n = 5), Ge(4+) (n = 5), or P(5+) (n = 4)). The basic electronic and redox features of Ru(L)-substituted Keggin- and Dawson-type heteropolytungstates (with L = H2O or O(2-)) were analyzed by means of density functional calculations. Similar to the corresponding α-Keggin-type derivatives, both α1-RuH2O and α2-RuH2O show catalytic activity for water oxidation.
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Heptanickel(ii) double-cubane core in wells-dawson heteropolytungstate, [Ni7(OH)6(H2O)6(P2W15O56)2](16-). Chem Commun (Camb) 2016; 52:2601-4. [PMID: 26751147 DOI: 10.1039/c5cc09823h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The hepta-Ni(2+)-containing 30-tungsto-4-phosphate(v) [Ni7(OH)6(H2O)6(P2W15O56)2](16-) (1) has been synthesized in aqueous, slightly basic medium under conventional reaction conditions, and charactarized via different physical methods. Single-crystal XRD showed that 1 consists of a corner-fused double-cubane {Ni7(OH)6(H2O)6}(8+) fragment sandwiched by two trilacunary [P2W15O56](12-) units. Polyanion 1 is solution-stable as shown by (31)P NMR. Ferromagnetic coupling interaction between the 7 paramagnetic centers of the double-cubane core in 1 with a S = 7 ground state was demonstrated. Electrochemical studies were also performed on 1.
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Tetradecanuclear Iron(III)-Oxo Nanoclusters Stabilized by Trilacunary Heteropolyanions. Inorg Chem 2015; 54:6136-46. [DOI: 10.1021/acs.inorgchem.5b00124] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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17
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Toward an Understanding of the Oxidation Process of Methionine Enkephalin: A Combined Electrochemistry, Quantum Chemistry and Quantum Chemical Topology Analysis. J Phys Chem B 2015; 119:6885-93. [DOI: 10.1021/acs.jpcb.5b01207] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Syntheses, crystal structure, electrochemistry and luminescence properties of lanthano–germanotungstates. RSC Adv 2015. [DOI: 10.1039/c5ra19726k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
[Ln(α-GeW11O39)2]13− (Ln = LaIII and CeIII) and [{Ln(μ-CH3COO)GeW11O39(H2O)}2]12− (Ln = PrIII, NdIII and SmIII) complexes were synthesized using a one-pot reaction. Similar complexes were isolated and their electrochemical and photochromic properties were studied.
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Effect of low-level laser therapy on the gene expression of collagen and vascular endothelial growth factor in a culture of fibroblast cells in mice. Lasers Med Sci 2014; 30:203-8. [PMID: 25171833 DOI: 10.1007/s10103-014-1644-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 08/21/2014] [Indexed: 01/16/2023]
Abstract
Low-level laser therapy treatment (LLLT) is widely used in rehabilitation clinics with the aim of accelerating the process of tissue repair; however, the molecular bases of the effect of LLLT have not been fully established. The aim of the present study was to evaluate the influence of the exposure of different doses of LLLT on the expression of collagen genes type I alpha 1 (COL1α1) and vascular endothelial growth factor (VEGF) in the fibroblast cells of mice (L929) cultivated in vitro. Fibroblast cells were irradiated with a Gallium-Arsenide laser (904 nm) every 24 h for 2 consecutive days, stored in an oven at 37 °C, with 5% CO2 and divided into 3 groups: G1-control group, G2-irradiated at 2 J/cm(2), and G3-irradiated at 3 J/cm(2). After irradiation, the total RNA was extracted and used in the complementary DNA (cDNA) synthesis. The gene expression was analyzed by real-time polymerase chain reaction. The cells irradiated in G2 exhibited a statistically significant growth of 1.78 in the expression of the messenger RNA (mRNA) of the COL1α1 gene (p = 0.036) in comparison with G1 and G3. As for the VEGF gene, an increase in expression was observed in the two irradiated groups in comparison with the control group. There was an increase in expression in G2 of 2.054 and G3 of 2.562 (p = 0.037) for this gene. LLLT (904 nm) had an influence on the expression of the genes COL1α1 (2 J/cm(2)) and VEGF (2 e 3 J/cm(2)) in a culture of the fibroblast cells of mice.
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Effect of Electron (De)localization and Pairing in the Electrochemistry of Polyoxometalates: Study of Wells–Dawson Molybdotungstophosphate Derivatives. Inorg Chem 2014; 53:5941-9. [DOI: 10.1021/ic500087t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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21
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183W INADEQUATE 2D NMR Spectroscopy of Hetero Arsenato–Phosphato–Tungstate PV/AsV Substitution in Dawson-Type α-[AsxP2–xW18O62]6– (x = 0–2) and α-[H4AsyP1–yW18O62]7– (y = 0, 1). Inorg Chem 2014; 53:5568-74. [DOI: 10.1021/ic500286v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Electrochemical behaviour of mixed d metal-iron containing Wells-Dawson sandwich-type complexes: [(FeOH2)2M2(X2W15O56)2]− and [(MOH2)2Fe2(X2W15O56)2]− (M = CrIII, MnIII, MnII, CoII, NiII, CuII, ZnII, X = AsV or PV and n = 12 or 14). Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2014.01.151] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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23
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Lanthanoid containing phosphotungstates: the syntheses, crystal structure, electrochemistry, photoluminescence and magnetic properties. Dalton Trans 2014; 43:8290-9. [DOI: 10.1039/c4dt00260a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A series of Peacock and Weakley type dimers was synthesized in a one pot reaction with high yield using ligand [P2W19O69(H2O)]14−. All nano clusters were structurally characterized by various analytical techniques.
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Oxidation of methionine-containing peptides by OH radicals: Is sulfoxide the only product? Study by mass spectrometry and IRMPD spectroscopy. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.10.057] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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25
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Synthesis, Magnetism, and Electrochemistry of the Ni14- and Ni5-Containing Heteropolytungstates [Ni14(OH)6(H2O)10(HPO4)4(P2W15O56)4]34– and [Ni5(OH)4(H2O)4(β-GeW9O34)(β-GeW8O30(OH))]13–. Inorg Chem 2013; 52:8399-408. [DOI: 10.1021/ic400943j] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Polyoxopalladates encapsulating 8-coordinated metal ions, [MO8Pd(II)12L8]n- (M = Sc3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Lu3+; L = PhAsO3(2-), PhPO3(2-), SeO3(2-)). Inorg Chem 2012. [PMID: 23194400 DOI: 10.1021/ic301537n] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A total of 16 discrete polyoxopalladates(II) [MO(8)Pd(II)(12)L(8)](n-), with a metal ion M encapsulated in a cuboid-shaped {Pd(12)O(8)L(8)} cage, have been synthesized: the phenylarsonate-capped series (1) L = PhAsO(3)(2-), M = Sc(3+) (ScPhAs), Mn(2+) (MnPhAs), Fe(3+) (FePhAs), Co(2+) (CoPhAs), Ni(2+) (NiPhAs), Cu(2+) (CuPhAs), Zn(2+) (ZnPhAs); the phenylphosphonate-capped series: (2) L = PhPO(3)(2-), M = Cu(2+) (CuPhP), Zn(2+) (ZnPhP); and the selenite-capped series (3) L = SeO(3)(2-), M = Mn(2+) (MnSe), Fe(3+) (FeSe), Co(2+) (CoSe), Ni(2+) (NiSe), Cu(2+), (CuSe), Zn(2+) (ZnSe), Lu(3+) (LuSe)). The polyanions were prepared in one-pot reactions in aqueous solution of [Pd(3)(CH(3)COO)(6)] with an appropriate salt of the metal ion M, as well as PhAsO(3)H(2), PhPO(3)H(2), and SeO(2), respectively, and then isolated as hydrated sodium salts Na(n)[MO(8)Pd(II)(12)L(8)]·yH(2)O (y = 10-37). The compounds were characterized in the solid state by IR spectroscopy, single-crystal XRD, elemental and thermogravimetric analyses. The solution stability of the diamagnetic polyanions ScPhAs, ZnPhAs, ZnPhP, ZnSe, and LuSe was confirmed by multinuclear ((77)Se, (31)P, (13)C, and (1)H) NMR spectroscopy. The polyoxopalladates ScPhAs, MnPhAs, CoPhAs, and CuPhAs were investigated by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS). Electrochemical studies on the manganese- and iron-containing derivatives demonstrated that the redox properties of the Mn(2+), Fe(3+), and Pd(2+) centers in the polyanions are strikingly influenced by the nature of the capping group. These results have subsequently been verified by density functional theory (DFT) calculations. Interestingly, electron paramagnetic resonance (EPR) measurements suggest that the coordination geometry around Mn(2+) is dynamically distorted on the EPR time scale (∼10(-11) s), whereas it appears as a static ensemble with cubic symmetry on the X-ray diffraction (XRD) time-scale (10(-15) s). The octacoordinated Cu(2+) cuboid is similarly distorted, in good agreement with DFT calculations. Interestingly, g(∥) is smaller than g(⊥), which is quite unusual, needing further theoretical development.
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Direct and mediated electrochemical response of the cytochrome P450 106A2 from Bacillus megaterium ATCC 13368. Bioelectrochemistry 2012; 87:71-7. [DOI: 10.1016/j.bioelechem.2012.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 01/12/2012] [Accepted: 01/20/2012] [Indexed: 11/27/2022]
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The one-electron reduction potential of methionine-containing peptides depends on the sequence. J Phys Chem B 2012; 116:9352-62. [PMID: 22747412 DOI: 10.1021/jp304741e] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The protein residue methionine (Met) is one of the main targets of oxidizing free radicals produced in oxidative stress. Despite its biological importance, the mechanism of the oxidation of this residue is still partly unknown. In particular the one-electron redox potentials of the couple Met(•+)/Met have not been measured. In this work, two approaches, experimental as well as theoretical, were applied for three dipeptides L-Met L-Gly, L-Gly L-Met and L-Met L-Met. Measurements by electrochemistry indicated differences in the ease of oxidation. Two DFT methods (BH&HLYP and PBE0) with two basis sets (6-31G(d) and 6-311+G(2d,2p)) were used to determine the redox potentials of Met in these peptides present in different conformations. In agreement with experimental results, we show that they vary with the sequence and the spatial structure of the peptide, most of the values being higher than 1 V (up to 2 V) vs NHE.
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Poly(ionic liquid) and macrocyclic polyoxometalate ionic self-assemblies: new water-insoluble and visible light photosensitive catalysts. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c1jm14573h] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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M234Glu is a component of the proton sponge in the reaction center from photosynthetic bacteria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1505-15. [PMID: 19632193 DOI: 10.1016/j.bbabio.2009.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 07/13/2009] [Accepted: 07/15/2009] [Indexed: 10/20/2022]
Abstract
Bacterial reaction centers use light energy to couple the uptake of protons to the successive semi-reduction of two quinones, namely Q(A) and Q(B). These molecules are situated symmetrically in regard to a non-heme iron atom. Four histidines and one glutamic acid, M234Glu, constitute the five ligands of this atom. By flash-induced absorption spectroscopy and delayed fluorescence we have studied in the M234EH and M234EL variants the role played by this acidic residue on the energetic balance between the two quinones as well as in proton uptake. Delayed fluorescence from the P(+)Q(A)(-) state (P is the primary electron donor) and temperature dependence of the rate of P(+)Q(A)(-) charge recombination that are in good agreement show that in the two RC variants, both Q(A)(-) and Q(B)(-) are destabilized by about the same free energy amount: respectively approximately 100 +/- 5 meV and 90 +/- 5 meV for the M234EH and M234EL variants, as compared to the WT. Importantly, in the M234EH and M234EL variants we observe a collapse of the high pH band (present in the wild-type reaction center) of the proton uptake amplitudes associated with formation of Q(A)(-) and Q(B)(-). This band has recently been shown to be a signature of a collective behaviour of an extended, multi-entry, proton uptake network. M234Glu seems to play a central role in the proton sponge-like system formed by the RC protein.
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Molecular Interactions between Wells−Dawson Type Polyoxometalates and Human Serum Albumin. Biomacromolecules 2008; 9:812-7. [DOI: 10.1021/bm701120j] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Polyoxometalate Binding to Human Serum Albumin: A Thermodynamic and Spectroscopic Approach. J Phys Chem B 2007; 111:11253-9. [PMID: 17784743 DOI: 10.1021/jp072947u] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The molecular recognition of polyoxometalates by human serum albumin is studied using two different polyoxometalates (POMs) at pH 7.5. The results are compared with those obtained at pH 3.5 and 9.0. At pH 7.5, both POMs strongly interact with the protein with different binding behaviors. The Keggin shaped POM, [H(2)W(12)O(40)](6-) (H2W12), specifically binds the protein, forming a complex with a 1:1 stoichiometry with Ka = 2.9 x 10(6) M(-1). The binding constant decreased dramatically with the increase of the ionic strength, thus indicating a mostly electrostatic binding process. Isothermal titration calorimetry (ITC) experiments show that the binding is an enthalpically driven exothermic process. For the wheel shaped POM [NaP(5)W(30)O(110)](14-) (P5W30), there are up to five binding sites on the protein. Increasing the ionic strength changes the binding behavior significantly, leading to a simple exothermic process, with several binding sites. Competitive binding experiments indicate that the two POMs share one common binding site. In addition, they show the existence of another important binding site for P5W30. The two POMs exhibit different binding dependences on the pH. The combination of the experimental results with the knowledge of the surface map of the protein in its N-B conformation transition domain leads to the proposal for the probable binding site of POMs. The present work reveals a protein conformation change upon P5W30 binding, a new feature not explicitly documented in previous studies.
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The Ball-Shaped Heteropolytungstates [{Sn(CH3)2(H2O)}24{Sn(CH3)2}12(A-XW9O34)12]36− (X=P, As): Stability, Redox and Electrocatalytic Properties in Aqueous Media. Chemistry 2007; 13:5480-91. [PMID: 17443832 DOI: 10.1002/chem.200601870] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The electrochemical behavior of the ball-shaped heteropolytungstates [[Sn(CH(3))(2)(H(2)O)](24)[Sn(CH(3))(2)](12)(A-XW(9)O(34))(12)](36-) (X=P, 1; As, 2) was examined in aqueous electrolytes by redissolution of their respective mixed cesium-sodium salts Cs(14)Na(22)[[Sn(CH(3))(2)(H(2)O)](24)[Sn(CH(3))(2)](12) (A-PW(9)O(34))(12)]149 H(2)O (Cs(14)-1) and Cs(14)Na(22)[[Sn(CH(3))(2)(H(2)O)](24)[Sn(CH(3))(2)](12)(A-AsW(9)O(34))(12)]149 H(2)O (Cs(14)-2). In the studied media, Cs(14)-2 is readily soluble in contrast to the significantly less soluble Cs(14)-1. The solubility of Cs(14)-1 is increased by the presence of Li(+) ions in solution. Gel filtration studies with 1 and 2 rule out a decay of the dodecameric spherical assemblies to Keggin-based monomers on the timescale of the experiment. By UV/Vis spectroscopy and cyclic voltammetry, 2 was found to be significantly less stable than 1 and both polyanions also show rather different decomposition pathways. Polyanion 1 collapses first into Keggin-type monomers which might contain the trilacunary [A-alpha-PW(9)O(34)](9-). The final monomeric species obtained from 1 appears to be very similar to [PW(11)O(39)](7-), which is the final transformation product of [A-alpha-PW(9)O(34)](9-) in the same media. In contrast, 2 does not seem to follow an analogous transformation pathway as that of the trilacunary [A-alpha-AsW(9)O(34)](9-). Importantly, stabilization of 1 is observed in chloride media. The fairly long-term stability of 1 in 1 M LiCl, pH 3, has allowed for its electrochemical study to be carried out. The solid-state cyclic voltammogram of 1 entrapped in a carbon paste electrode shows the same characteristics as 1 dissolved in chloride solutions, thus supporting the conclusion that the polyanion is stable in these environments. Controlled potential coulometry on 1 indicates that the number of electrons consumed in the first wave is larger than twenty. To our knowledge, 1 constitutes the first example of a molecule that can take up such a large number of electrons resulting in a chemically reversible W-wave. These properties show promise for future fundamental and applied studies. Polyanion 1 is also efficient in the electrocatalytic reduction of NO(x), including nitrate. Finally, a remarkable interaction was found between 1 and NO, a highly promising feature for biomimetic applications.
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Dititanium-Containing 19-Tungstodiarsenate(III) [Ti2(OH)2As2W19O67(H2O)]8−: Synthesis, Structure, Electrochemistry, and Oxidation Catalysis. Chemistry 2007; 13:4733-42. [PMID: 17506049 DOI: 10.1002/chem.200700043] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The dititanium-containing 19-tungstodiarsenate(III) [Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)](8-) (1) has been synthesized and characterized by IR, TGA, elemental analysis, electrochemistry, and catalytic studies. Single-crystal X-ray analysis was carried out on Cs(8)[Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)].2CsCl.12H(2)O (Cs-1), which crystallizes in the monoclinic system, space group P2(1)/m, with a=12.7764(19), b=19.425(3), c=18.149(3) A, beta=110.234(3) degrees, and Z=2. Polyanion 1 comprises two (B-alpha-As(III)W(9)O(33)) Keggin moieties linked through an octahedral {WO(5)(H(2)O)} fragment and two unprecedented square-pyramidal {TiO(4)(OH)} groups, leading to a sandwich-type structure with nominal C(2v) symmetry. Synthesis of 1 was accomplished by reaction of TiOSO(4) and K(14)[As(2)W(19)O(67)(H(2)O)] in a 2:1 molar ratio in aqueous, acidic medium (pH 2). Polyanion 1 could also be isolated as a tetra-n-butyl ammonium (TBA) salt, {(n-C(4)H(9))(4)N}(5)H(3)[Ti(2)(OH)(2)As(2)W(19)O(67)(H(2)O)] (TBA-1). TBA-1 was studied by cyclic voltammetry in acetonitrile (MeCN) solutions containing 0.1 M LiClO(4) and compared with the results obtained with Cs-1 in aqueous media. In MeCN, the Ti(IV) and W(VI) waves could not be separated distinctly. An important adsorption phenomenon on the glassy carbon working electrode was encountered both in cyclic voltammetry and in controlled potential electrolysis and was confirmed by Electrochemical Quartz Crystal Microbalance (EQCM) studies on a carbon film. TBA-1, dissolved in MeCN, reacts with H(2)O(2) to give peroxo complexes stable enough for characterization by UV-visible spectroscopy, cyclic voltammetry, and EQCM. TBA-1 shows high catalytic activity (TOF=11.3 h(-1)) in cyclohexene oxidation with aqueous H(2)O(2) producing products typical of a heterolytic oxidation mechanism. The stability of TBA-1 under turnover conditions was confirmed by using IR, UV-visible spectroscopy as well as cyclic voltammetry.
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Effect of Cyanato, Azido, Carboxylato, and Carbonato Ligands on the Formation of Cobalt(II) Polyoxometalates: Characterization, Magnetic, and Electrochemical Studies of Multinuclear Cobalt Clusters. Chemistry 2007; 13:3525-36. [PMID: 17226868 DOI: 10.1002/chem.200601252] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Five Co(II) silicotungstate complexes are reported. The centrosymmetric heptanuclear compound K(20)[{(B-beta-SiW(9)O(33)(OH))(beta-SiW(8)O(29)(OH)(2))Co(3)(H(2)O)}(2)Co(H(2)O)(2)]47 H(2)O (1) consists of two {(B-beta-SiW(9)O(33)(OH))(beta-SiW(8)O(29)(OH)(2))Co(3)(H(2)O)} units connected by a {CoO(4)(H(2)O)(2)} group. In the chiral species K(7)[Co(1.5)(H(2)O)(7))][(gamma-SiW(10)O(36))(beta-SiW(8)O(30)(OH))Co(4)(OH)(H(2)O)(7)]36 H(2)O (2), a {gamma-SiW(10)O(36)} and a {beta-SiW(8)O(30)(OH)} unit enclose a mononuclear {CoO(4)(H(2)O)(2)} group and a {Co(3)O(7)(OH)(H(2)O)(5)} fragment. The two trinuclear Co(II) clusters present in 1 enclose a mu(4)-O atom, while in 2 a mu(3)-OH bridging group connects the three paramagnetic centers of the trinuclear unit, inducing significantly larger Co-L-Co (L=mu(4)-O (1), mu(3)-OH (2)) bridging angles in 2 (theta(av(Co-L-Co))=99.1 degrees ) than in 1 (theta(av(Co-L-Co))=92.8 degrees ). Weaker ferromagnetic interactions were found in 2 than in 1, in agreement with larger Co-L-Co angles in 2. The electrochemistry of 1 was studied in detail. The two chemically reversible redox couples observed in the positive potential domain were attributed to the redox processes of Co(II) centers, and indicated that two types of Co(II) centers in the structure were oxidized in separate waves. Redox activity of the seventh Co(II) center was not detected. Preliminary experiments indicated that 1 catalyzes the reduction of nitrite and NO. Remarkably, a reversible interaction exists with NO or related species. The hybrid tetranuclear complexes K(5)Na(3)[(A-alpha-SiW(9)O(34))Co(4)(OH)(3)(CH(3)COO)(3)]18 H(2)O (3) and K(5)Na(3)[(A-alpha-SiW(9)O(34))Co(4)(OH)(N(3))(2)(CH(3)COO)(3)]18 H(2)O (4) were characterized: in both, a tetrahedral {Co(4)(L(1))(L(2))(2)(CH(3)COO)(3)} (3: L(1)=L(2)=OH; 4: L(1)=OH, L(2)=N(3)) unit capped the [A-alpha-SiW(9)O(34)](10-) trivacant polyanion. The octanuclear complex K(8)Na(8)[(A-alpha-SiW(9)O(34))(2)Co(8)(OH)(6)(H(2)O)(2)(CO(3))(3)]52 H(2)O (5), containing two {Co(4)O(9)(OH)(3)(H(2)O)} units, was also obtained. Compounds 2, 3, 4, and 5 were less stable than 1, but their partial electrochemical characterization was possible; the electronic effect expected for 3 and 4 was observed.
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Evidence for Delocalized Anticooperative Flash Induced Proton Binding as Revealed by Mutants at the M266His Iron Ligand in Bacterial Reaction Centers. Biochemistry 2007; 46:4510-21. [PMID: 17378585 DOI: 10.1021/bi602416s] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bacterial reaction centers (RCs) convert light energy into chemical free energy via the double reduction and protonation of the secondary quinone electron acceptor, QB, to the dihydroquinone QBH2. Two RC mutants (M266His --> Leu and M266His --> Ala) with a modified ligand of the non-heme iron have been studied by flash-induced absorbance change spectroscopy. No important changes were observed for the rate constants of the first and second electron transfers between the first quinone electron acceptor, QA, and QB. However, in the M266HL mutant a destabilization of approximately 40 meV of the free energy level of QA- was observed, at variance with the M266HA mutant. The superposition of the three-dimensional X-ray structures of the three proteins in the QA region provides no obvious explanation for the energy modification in the M266HL mutant. The shift of the midpoint redox potential of QA/QA- in M266HL caused accelerated recombination of the charges in the P+ QA- state of the RCs where the native QA was replaced by a low potential anthraquinone (AQA). As previously reported for the native RCs, in the M266HL we observed a biphasicity of the P+ AQA- --> P AQA charge recombination. Interestingly, both phases present a similar acceleration in the M266HL mutant with respect to the wild type. The pH dependencies of the proton uptake upon QA- and QB- formations are superimposable in both mutants but very different from those of native RCs. The data measured in mutants are similar to those that we previously obtained on strains modified at various sites of the cytoplasmic region. The similarity of the response to these different mutations is puzzling, and we propose that it arises from a collective behavior of multiple acidic residues resulting in strongly anticooperative proton binding. The unspecific disappearance of the high pH band of proton uptake observed in all these mutants appears as the natural consequence of removing any member of an interactive proton cluster. This long range interaction also accounts for the similar responses to mutations of the proton uptake pattern induced by either QA- or QB-. We surmise that the presence of an extended protonated water H-bond network providing protons to QB is responsible for these effects.
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Molecular interaction and energy transfer between human serum albumin and polyoxometalates. J Phys Chem B 2007; 111:1809-14. [PMID: 17256886 DOI: 10.1021/jp063758z] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
As a step toward the elucidation of the mechanistic pathways governing the known bioactivity of polyoxometalates (POMs), two representative molecules of this class of chemicals, the wheel-shaped [NaP(5)W(30)O(110)]14- (P(5)W(30)) and the Keggin-type anion [H(2)W(12)O(40)]6- (H(2)W(12)), are shown, by two independent techniques, to interact with the fatty-acid-free human serum albumin (HSA). The excited-state lifetime of the single tryptophan molecule of this protein is dramatically decreased by the binding. The quenching mechanism is found to constitute the first example of energy transfer between HSA and POMs. Such molecular recognition is believed to be a key step for subsequent evolution of the systems. Circular dichroism (CD) was used to assess the structural effects of POM binding on HSA and to confirm the interaction revealed by fluorescence studies. CD experiments showed that the two POMs have different effects on the secondary structure of the protein. Binding P(5)W(30) partially unfolds the protein whereas H(2)W(12) has no remarkable effect on the structure of the protein.
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Electrochemical generation of high-valent manganese catalysts in aqueous solutions from the sandwich-type polyoxoanion [(MnIII(H2O))3(SbW9O33)2]9−. Electrochem commun 2007. [DOI: 10.1016/j.elecom.2006.08.051] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Preliminary electrochemical studies of the flavohaemoprotein from Ralstonia eutropha entrapped in a film of methyl cellulose: Activation of the reduction of dioxygen. Bioelectrochemistry 2007; 70:185-91. [PMID: 16750432 DOI: 10.1016/j.bioelechem.2006.03.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Indexed: 11/19/2022]
Abstract
A flavohaemoprotein (FHP) from Ralstonia eutropha, obtained in a pure and active form, has been entrapped in a film of methyl cellulose on the electrode surface and gives a stable and reproducible electrochemical response at pH 7.00 when subject to cyclic voltammetry using a glassy carbon electrode. To our knowledge, no previous direct electrochemistry had been achieved with a bacterial flavohaemoglobin, which possess both a FAD and a haem. A single couple is observed which is assigned to the haem moiety of the protein, since the same result is obtained with a semi-apo form of the protein deprived of FAD (semi-apo FHP). The data collected were further confirmed by potentiometry with a platinum electrode, and the homogeneous electron transfer rate estimated by double potential step chronocoulometry at a bare glassy carbon electrode in the presence of methyl viologen (MV). The presence of FAD in the holoprotein is easily confirmed by UV-Vis spectrophotometry, but its expected electron relay role remains elusive. The protein activates the reduction of dioxygen by about 400 mV, the reduction current being proportional to the concentration of dioxygen up to 10% in volume in the gas mixture.
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Synthesis and Anti-Mycobacterial Activity of N-[(E)-(Disubstituted- Phenyl)Methylidene]Isonicotino-Hydrazide Derivatives. LETT DRUG DES DISCOV 2005. [DOI: 10.2174/157018005774479131] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Cobalt-Containing Silicotungstate Sandwich Dimer [{Co3(B-β-SiW9O33(OH))(B-β-SiW8O29(OH)2)}2]22-. Inorg Chem 2005; 44:9360-8. [PMID: 16323921 DOI: 10.1021/ic0515554] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The 6-cobalt-substituted [{Co3(B-beta-SiW9O33(OH))(B-beta-SiW8O29(OH)2)}2]22- has been characterized by IR and UV-vis spectroscopy, elemental analysis, magnetic studies, electrochemistry, and gel filtration chromatography. A single-crystal X-ray analysis was carried out on K10Na12[{Co3(B-beta-SiW9O33(OH))(B-beta-SiW8O29(OH)2)}2].49H2O (KNa-1), which crystallizes in the monoclinic system, space group P2(1)/n, with a=19.9466(8) A, b=24.6607(10) A, c=34.0978(13) A, beta=102.175(1) degrees, and Z=2. Polyanion 1 represents a novel class of asymmetric sandwich-type polyanions. It contains three cobalt ions, which are encapsulated between an unprecedented (B-beta-SiW9O34) fragment and a (B-beta-SiW8O31) unit. Polyanion 1 is composed of two sandwich species via two Co-O-W bridges in the solid state and almost certainly in solution as well based on gel filtration chromatography. UV-visible spectroscopy and cyclic voltammetry also confirmed its stability. Two well-separated groups of waves appeared in the voltammetric pattern: the wave observed in the negative potential range versus a saturated calomel electrode features the redox processes of WVI centers; the two reversible redox couples observed in the positive potential domain are attributed to the redox processes of Co2+ centers and indicated that the two types of Co2+ centers in the structure are oxidized in separate waves. Such reversibility of Co2+ centers within multi-Co-substituted polyoxometalates is uncommon. The magnetic properties of KNa-1 are also discussed. The ferromagnetic ground state has been studied by magnetic susceptibility and magnetization measurements and fitted according to an anisotropic exchange model.
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Primary evaluation of patients suspected of having interstitial cystitis (IC). Eur Urol 2004; 45:662-9. [PMID: 15082211 DOI: 10.1016/j.eururo.2003.11.021] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2003] [Indexed: 10/26/2022]
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Characterization of the Electrochemical Oxidation of Peroxynitrite: Relevance to Oxidative Stress Bursts Measured at the Single Cell Level. Chemistry 2001. [DOI: 10.1002/1521-3765(20011001)7:19%3c4171::aid-chem4171%3e3.0.co;2-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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In vitro platelet hypoaggregability to ADP after body hypothermia in anaesthesized dogs is due to phenobarbital. Thromb Res 1992; 66:609-12. [PMID: 1523615 DOI: 10.1016/0049-3848(92)90316-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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46
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Proteins C and S in patients with advanced prostatic cancer. Thromb Res 1991; 63:195-200. [PMID: 1835181 DOI: 10.1016/0049-3848(91)90282-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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