Redox equilibria of the nitrosonium cation and of its nonbonded complexes

Lee, K. Y.; Kuchynka, D. J.; Kochi, Jay K.

doi:10.1021/ic00346a008

Cited by 111 publications

(82 citation statements)

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“…Nitrosonium ion, NO + , formed by disproportionation [33] of nitrito dimer B (Figure 3), is a good single-electron oxidant, as indicated by its reduction potential (E°= 1.19 V vs. SCE). [34] In path A, an electron transfer between phenoxide anion 21a (or from the corresponding phenol 1a) and nitrosonium ion NO + gives the phenoxyl radical 16a and nitrogen monoxide. Coupling of these two radicals leads to nitrosophenol.…”

Section: Resultsmentioning

confidence: 99%

New Insights into the Reactivity of Nitrogen Dioxide with Substituted Phenols: A Solvent Effect

2005

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Various alkyl‐substituted phenols react readily with nitrogen dioxide (·NO2) in different solvents at room temperature. In all cases nitration is the major reaction and leads to the formation of mono‐ and dinitrophenols and 4‐nitrocyclohexa‐2,5‐dienones from 2,4,6‐tri‐substituted phenols. Oxidation, dimerisation and, in one case, nitrosation are also observed. The reaction pathway followed changes according to the solvent and to the nature and the number of substituents on the phenolic ring. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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Section: Resultsmentioning

confidence: 99%

New Insights into the Reactivity of Nitrogen Dioxide with Substituted Phenols: A Solvent Effect

2005

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“…This fact should be attributed to the coordination of NO + by the bubbled complexes that is assumed to be present in this type of solution. [12] DMSO solutions of the compounds obtained by bubbling NO through solutions of complexes 2, 3 and 4 in dichloromethane were studied by voltammetry. The results of these experiments were also similar to those found for compounds 5, 6 and 7, respectively.…”

Section: Resultsmentioning

confidence: 99%

Ruthenium Complexes of the Scorpionate Ligand Bis(3,5‐dimethylpyrazol‐1‐yl)dithioacetate and the Effect of Nitric Oxide Coordination

et al. 2005

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Six new ruthenium(II) complexes with the scorpionateligand bis(3,5‐dimethylpyrazol‐1‐yl)dithio‐κ3N,N,S‐acetate (bdmpzdta) were obtained by treatment of the ligand with RuCl3 or [RuCl3(NO)] in 1:1 or 2:1 molar ratios in the presence or absence of ethylenediamine. In all six complexes the pyrazolic rings lie in the equatorial plane. The mononitrosyl complexes present a sharp ν(NO) band in the range 1864–1859 cm–1 for samples prepared either as KBr tablets or dichloromethane solutions. In the case of [Ru(NO)(bdmpzdta)2]Cl (7), the dithiocarboxylate group of one of the ligands is not coordinated (κ2N,N). In the other five complexes, however, bdmpzdta behaves as a κ3N,N,S scorpionate ligand. When the complexes obtained from RuCl3 were dissolved in dichloromethane and NO was bubbled through the solution, a high degree of coordination of NO+ was observed, according to IR, UV and voltammetric studies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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“…11 Under equivalent conditions, the oxidation potential of HNO is -0.11 V (vs NHE) 13 and therefore the reduction of Cu(II) to Cu(I) in BOT1 is thermodynamically favored. In contrast, oxidation of NO to give the nitrosonium cation NO + occurs at 1.52 V (vs NHE) 14 and therefore NO is not able to reduce CuBOT1.…”

Section: Fluorescent Sensors Based On Copper Complexes Of Triazolyl(dmentioning

confidence: 96%

Metal-Based Optical Probes for Live Cell Imaging of Nitroxyl (HNO)

Rivera‐Fuentes

Lippard

2015

Acc. Chem. Res.

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Conspectus: Nitroxyl (HNO) is a biological signaling agent that displays distinctive reactivity compared to nitric oxide (NO). As a consequence, these two reactive nitrogen species trigger different physiological responses. Selective detection of HNO over NO has been a challenge for chemists, and several fluorogenic molecular probes have been recently developed with that goal in mind. Common constructs take advantage of the HNO-induced reduction of Cu(II) to Cu(I).The sensing mechanism of such probes relies on the ability of the unpaired electron in a d orbital of the Cu(II) center to quench the fluorescence of a photoemissive ligand by either an electron or energy transfer mechanism. Experimental and theoretical mechanistic studies suggest that proton-coupled electron transfer mediates this process, and careful tuning of the copper coordination environment has led to sensors with optimized selectivity and kinetics.The current optical probes cover the visible and near-infrared regions of the spectrum. This palette of sensors comprises structurally and functionally diverse fluorophores such as coumarin 2 (blue/green emission), boron dipyrromethane (BODIPY, green emission), benzoresorufin (red emission), and dihydroxanthenes (near-infrared emission). Many of these sensors have been successfully applied to detect HNO production in live cells. For example, copper-based optical probes have been used to detect HNO production in live mammalian cells that have been treated with H 2 S and various nitrosating agents. These studies have established a link between HSNO, the smallest S-nitrosothiol, and HNO. In addition, a near-infrared HNO sensor has been used to perform multicolor/multianalyte microscopy, revealing that exogenously applied HNO elevates the concentration of intracellular mobile zinc. This mobilization of zinc ions is presumably a consequence of nitrosation of cysteine residues in zinc-chelating proteins such as metallothionein.Future challenges for the optical imaging of HNO include devising probes that can detect HNO reversibly, especially because ratiometric imaging can only report equilibrium concentrations when the sensing event is reversible. Another important aspect that needs to be addressed is the creation of probes that can sense HNO in specific subcellular locations. These tools would be useful to identify the organelles in which HNO is produced in mammalian cells and probe the intracellular signaling networks in which this reactive nitrogen species is involved. In addition, near-infrared emitting probes might be applied to detect HNO in thicker specimens, such as acute tissue slices and even live animals, enabling the investigation of the roles of HNO in physiological or pathological conditions in multicellular systems.

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Redox equilibria of the nitrosonium cation and of its nonbonded complexes

Cited by 111 publications

References 1 publication

New Insights into the Reactivity of Nitrogen Dioxide with Substituted Phenols: A Solvent Effect

New Insights into the Reactivity of Nitrogen Dioxide with Substituted Phenols: A Solvent Effect

Ruthenium Complexes of the Scorpionate Ligand Bis(3,5‐dimethylpyrazol‐1‐yl)dithioacetate and the Effect of Nitric Oxide Coordination

Metal-Based Optical Probes for Live Cell Imaging of Nitroxyl (HNO)

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