Spatiotemporal defined release of nitric oxide

Arulsamy, Navamoney; Bohle, D. Scott; Butikofer, Jeffrey L.; Stephens, Peter W.; Yee, Gordon T.

doi:10.1039/b404728a

Cited by 6 publications

(4 citation statements)

References 19 publications

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“… a The values of d 1i and d 2i for hydroquinone and p- quinone, respectively, are considered as the experimental bond lengths of the uncomplexed organic molecules. – The average values for C n1 −O HQ/Q , C n1 −C n2/n3 and C n2 −C n3 are 1.377 ± 0.004 Å, 1.385 ± 0.005 Å, and 1.384 ± 0.003 Å for the free hydroquinone and 1.266 ± 0.003 Å, 1.476 ± 0.002 Å, and 1.332 ± 0.005 for the free quinone [where C n1 refers to the carbon atom attached to the phenolate oxygen, C n2/n3 refer to the rest of the aromatic carbons, numbering shown in Figure ]. Δ values are the dioxolene charge calculated from eqs and . b These bonds are referred to V IV −O water and they appear in double because in the asymmetric unit of 1 there two independent molecules. c From ref . …”

Section: Resultsmentioning

confidence: 99%

“…The characteristic quinoidal distortion upon oxidation allows the partial electron transfer to be quantitatively evaluated at each organic redox center of the tetranuclear complexes. The linear relationship of the charge of o- dioxolenes (Δ) versus the bond lengths of all the six intraring C/C ligand distances is given by the eqs and , where d i is the i th bond length of the dioxolene moiety under examination, and d 1 i and d 2 i are the i th bond lengths of the uncomplexed hydroquinone and p- quinone molecules, – respectively and n the number of the dioxolene bonds. Δ i = − 2 ( d i − d 2i ) / ( d 1i − d 2i ) Δ = ( ∑ Δ i ) / n …”

Section: Resultsmentioning

confidence: 99%

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Solid State and Aqueous Solution Characterization of Rectangular Tetranuclear V^IV/V-p-Semiquinonate/Hydroquinonate Complexes Exhibiting a Proton Induced Electron Transfer

Drouza

Keramidas

2008

Inorg. Chem.

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Reaction of the non-innocent dinucleating ligand 2,5-bis[N,N-bis(carboxymethyl) aminomethyl]hydroquinone (H 6bicah) with VO (2+) and VO 4 (3-) salts in water in the pH range 2 to 4.5 provides a series of novel tetranuclear V (IV) and/or V (V) macrocycles with the main core consisting of the anions [V (V) 4O 4(mu-O) 2(mu-bicah) 2] (4-) isolated at pH = 2.5 and [V (IV) 2V (V) 2O 4(mu-O) 2(mu-bicas)(mu-bicah)] (5-) and [V (IV) 4O 4(mu-O) 2(mu-bicas) 2] (6-) isolated at pH = 4.5 (bicas (*5-) = 2,5-bis[N,N-bis(carboxymethyl) aminomethyl]- p-semiquinonate), whereas at pH = 2 the dinuclear [(V (IV)O) 2(OH 2) 2(mu-bicah)] (2-) was obtained. All vanadium compounds have been characterized, and the charge of the ligand has been assigned in solid state by X-ray crystallography and infrared spectroscopy. The structures of the tetranuclear anions consist of four vanadium atoms arranged at the corners of a rectangle with the two bridging bicas (*5-) and/or bicah (6-) ligands on the long and the two V (IV/V)-O-V (IV/V) bridges on the short sides of the rectangle. UV-vis, (51)V and (1)H NMR spectroscopy and electrochemistry showed that these complexes interconvert to each other by varying the pH. This pH induced redox transformation of the tetranuclear anions has been attributed to the shift of the reduction potential of the bicas (*5-) to higher values by decreasing the pH. The electron is transferred intramolecularly from the metal ion to the electron accepting semiquinones resulting in reduction of bicas (*5-) to bicah (6-) and concurrent oxidation of the V (IV) to V (V). The resulting complexes are further oxidized by atmospheric oxygen. This system as a model for the H (+) coupled redox reactions in metalloenzymes and its relevance is discussed briefly.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Solid State and Aqueous Solution Characterization of Rectangular Tetranuclear V^IV/V-p-Semiquinonate/Hydroquinonate Complexes Exhibiting a Proton Induced Electron Transfer

Drouza

Keramidas

2008

Inorg. Chem.

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“…Crystal Structure of the CO 2 −HQ Clathrate. Some molecular structures of HQ clathrates have already been published in the literature, such as those of xenon, 46 nitric oxide, 47 hydrogen sulfide, 48 and hydrogen chloride. 49 However, the molecular structure of HQ clathrate formed with carbon dioxide has not been described to date.…”

Section: Crystal Growth and Designmentioning

confidence: 99%

CO₂–Hydroquinone Clathrate: Synthesis, Purification, Characterization and Crystal Structure

Torré

Coupan

Chabod

et al. 2016

Crystal Growth & Design

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Organic clathrate compounds, particularly those formed between hydroquinone (HQ) and gases, are supramolecular entities recently highlighted as promising alternatives for applications such as gas storage and separation processes. This study provides new insights into CO 2 −HQ clathrate, which is a key structure in some of the proposed future applications of these compounds. We present a novel synthesis and purification of CO 2 −HQ clathrate monocrystals. Clathrate crystals obtained from a single synthesis and native HQ are characterized and compared using Raman/Fourier transform infrared/NMR spectroscopies, optical microscopy, and thermogravimetric analysis coupled to mass spectrometry. The molecular structure of the clathrate has been resolved by X-ray diffraction analysis, and detailed crystallographic information is presented for the first time.

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“…The oxidation state of the p - and o -dioxolene ligands can be reasonably established by examination of the C–O phenolate and the C–C aromatic bond lengths, which are strongly dependent on the formal charge of the ligands. ,,− d C–Ohydroquinonate ranges from 1.329(2) to 1.366(1) Å for 2 , 3 , and 4 is typical for the hydroquinonate complexes. − The shorter d C‑Osemiquinonate [1.297(2)–1.301(2) Å] lengths in complex 1 reveal the semiquinone oxidation state of the ligand. The oxidation state of the ligand was also calculated from eqs and (Δ = 0, −1, and −2 ideal values for quinone, semiquinonate, and hydroquinonate, respectively), ,, where d i is the i th bond length of the dioxolene moiety under examination, d 1 i and d 2 i are the i th bond lengths of the uncomplexed hydroquinone and p -quinone molecules, − respectively, and n is the number of the dioxolene bonds. …”

Section: Resultsmentioning

confidence: 99%

Aerial Oxidation of a V^IV–Iminopyridine Hydroquinonate Complex: A Trap for the V^IV–Semiquinonate Radical Intermediate

et al. 2015

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The reaction of 2,5-bis[N,N'-bis(2-pyridyl-aminomethyl)aminomethyl]-p-hydroquinone (H2bpymah) with VO(2+) salts in acetonitrile or water at a low pH (2.2-3.5) results in the isolation of [{V(IV)(O)(Cl)}2(μ-bpymah)], the p-semiquinonate complex [{V(IV)(O)(Cl)}2(μ-bpymas)](OH), the cyclic mixed-valent hexanuclear compound [{V(V)(O)(μ-O)V(IV)(O)}(μ-bpymah)]3, and [(V(V)O2)2(μ-bpymah)]. [{V(IV)(O)(Cl)}2(μ-bpymas)](OH) is an intermediate of the radical-mediated oxidation of [{V(IV)(O)(Cl)}2(μ-bpymah)] from O2. At lower pH values (2.2), a reversible intramolecular electron transfer from the metal to the ligand of [{V(IV)(O)(Cl)}2(μ-bpymas)](OH) is induced with the concurrent substitution of chlorine atoms by the oxygen-bridging atoms, resulting in the formation of [{V(V)(O)(μ-O)V(IV)(O)}(μ-bpymah)]3. The metal complexes were fully characterized by X-ray crystallography, infrared (IR) spectroscopy, and magnetic measurements in the solid state, as well as by conductivity measurements, UV-vis spectroscopy, and electrochemical measurements in solution. The oxidation states of the metal ions and ligands were determined by the crystallographic data. The [{V(IV)(O)(Cl)}2(μ-bpymah)]-[{V(IV)(O)(Cl)}2(μ-bpymas)](OH) redox process is electrochemically reversible. The V(IV) ion in the semiquinonate compound exhibits a surprisingly low oxophilicity, resulting in the stabilization of OH(-) counterions at acidic pH values. An investigation of the mechanism of this reaction reveals that these complexes induce the reduction of O2 to H2O2, mimicking the activity of enzymes incorporating two redox-active centers (metal-organic) in the active site.

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Spatiotemporal defined release of nitric oxide

Abstract: Nitric oxide's beta-quinol clathrate rapidly and quantitatively releases nitric oxide upon dissolution to give well defined spatiotemporal gradients.

Cited by 6 publications

References 19 publications

Solid State and Aqueous Solution Characterization of Rectangular Tetranuclear V^IV/V-p-Semiquinonate/Hydroquinonate Complexes Exhibiting a Proton Induced Electron Transfer

Solid State and Aqueous Solution Characterization of Rectangular Tetranuclear V^IV/V-p-Semiquinonate/Hydroquinonate Complexes Exhibiting a Proton Induced Electron Transfer

CO₂–Hydroquinone Clathrate: Synthesis, Purification, Characterization and Crystal Structure

Aerial Oxidation of a V^IV–Iminopyridine Hydroquinonate Complex: A Trap for the V^IV–Semiquinonate Radical Intermediate

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Spatiotemporal defined release of nitric oxide

Abstract: Nitric oxide's beta-quinol clathrate rapidly and quantitatively releases nitric oxide upon dissolution to give well defined spatiotemporal gradients.

Cited by 6 publications

References 19 publications

Solid State and Aqueous Solution Characterization of Rectangular Tetranuclear VIV/V-p-Semiquinonate/Hydroquinonate Complexes Exhibiting a Proton Induced Electron Transfer

Solid State and Aqueous Solution Characterization of Rectangular Tetranuclear VIV/V-p-Semiquinonate/Hydroquinonate Complexes Exhibiting a Proton Induced Electron Transfer

CO2–Hydroquinone Clathrate: Synthesis, Purification, Characterization and Crystal Structure

Aerial Oxidation of a VIV–Iminopyridine Hydroquinonate Complex: A Trap for the VIV–Semiquinonate Radical Intermediate

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Solid State and Aqueous Solution Characterization of Rectangular Tetranuclear V^IV/V-p-Semiquinonate/Hydroquinonate Complexes Exhibiting a Proton Induced Electron Transfer

Solid State and Aqueous Solution Characterization of Rectangular Tetranuclear V^IV/V-p-Semiquinonate/Hydroquinonate Complexes Exhibiting a Proton Induced Electron Transfer

CO₂–Hydroquinone Clathrate: Synthesis, Purification, Characterization and Crystal Structure

Aerial Oxidation of a V^IV–Iminopyridine Hydroquinonate Complex: A Trap for the V^IV–Semiquinonate Radical Intermediate