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Jay K. Kochi - One of the best experts on this subject based on the ideXlab platform.
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mechanism of inner sphere electron transfer via charge transfer precursor complexes redox energetics of aromatic donors with the Nitrosonium acceptor
Journal of the American Chemical Society, 2001Co-Authors: Sergiy V Rosokha, Jay K. KochiAbstract:Spontaneous formation of colored (1:1) complexes of various aromatic donors (ArH) with the Nitrosonium acceptor (NO+) is accompanied by the appearance of two new (charge-transfer) absorption bands in the UV−vis spectrum. IR spectral and X-ray crystallographic analyses of the [ArH,NO+] complexes reveal their inner-sphere character by the ArH/NO+ separation that is substantially less than the van der Waals contact and by the significant enlargement of the aromatic chromophore. The reversible interchange between such an inner-sphere complex [ArH,NO+] and the redox product (ArH+• + NO•) is quantitatively assessed for the first time to establish it as the critical intermediate in the overall electron-transfer process. Theoretical formulation of the NO+ binding to ArH is examined by LCAO-MO methodology sufficient to allow the unambiguous assignment of the pair of diagnostic (UV−vis) spectral bands. The MO treatment also provides quantitative insight into the high degree of charge-transfer extant in these inner-...
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charge transfer probes for molecular recognition via steric hindrance in donor acceptor pairs
Journal of the American Chemical Society, 1997Co-Authors: Rajendra Rathore, Sergey V Lindeman, Jay K. KochiAbstract:Molecular association of various aromatic hydrocarbons (D, including sterically hindered donors) with a representative group of diverse acceptors (A = quinone, trinitrobenzene, tetracyanoethylene, tropylium, tetranitromethane, and Nitrosonium) is visually apparent in solution by the spontaneous appearance of distinctive colors. Spectral (UV−vis) analyses of the colored solutions reveal their charge-transfer origin (λCT), and they provide quantitative information of the intermolecular association in the form of the KDA and eCT values for the formation and visualization, respectively, of different [D,A] complexes. Importantly, such measurements establish charge-transfer absorption to be a sensitive analytical tool for evaluating the steric inhibition of donor−acceptor association. For example, the steric differences among various hindered aromatic donors in their association with quinone are readily dramatized in their distinctive charge-transfer (color) absorptions and verified by X-ray crystallography of ...
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Direct Nitrosation of Aromatic Hydrocarbons and Ethers with the Electrophilic Nitrosonium Cation
The Journal of Organic Chemistry, 1994Co-Authors: Eric Bosch, Jay K. KochiAbstract:Various polymethylbenzenes and anisoles are selectively nitrosated with the electrophilic Nitrosonium salt NO+BF 4 - in good conversions and yields under mild conditions in which the conventional procedure (based on nitrite neutralization with strong acid) is ineffective. The reactivity patterns in acetonitrile deduced from the various time/conversions in Tables 2 and 3 indicate that aromatic nitrosation is distinctly different from those previously established for electrophilic aromatic nitration. The contrasting behavior of NO + in aromatic nitrosation is ascribed to a rate-limiting deprotonation of the reversibly formed Wheland intermediate, which in the case of aromatic nitration with NO 2 + occurs with no deuteric kinetic isotope effect. Aromatic nitroso derivatives (unlike the nitro counterpart) are excellent electron donors that are subject to a reversible one-electron oxidation at positive potentials significantly less than that of the parent polymethylbenzene or anisole. As a result, the series of nitrosobenzenes are also much better BrOnsted bases than the corresponding nitro derivatives, and this marked distinction, therfore, accounts for the large differentiation in the deprotonation rates of their respective conjugate acids (i.e. Wheland intermediates)
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time resolved charge transfer spectroscopy of aromatic electron donor acceptor complexes with Nitrosonium inner sphere mechanism for electron transfer in the isoergonic region
Journal of the American Chemical Society, 1992Co-Authors: T M Bockman, Z J Karpinski, S Sankararaman, Jay K. KochiAbstract:Photoinduced electron transfer in various 1:1 aromatic EDA complexes with Nitrosonium by the direct laser-pulse (20-ps and 10-ns fwhm) excitation of the charge-transfer bands leads to the spontaneous generation of the redox pair Ar .+ and NO. Temporal relaxation by back electron transfer to regenerate the EDA complex [Ar,NO + ] is meaured by following the spectral decay of Ar .+ with the aid of time-resolved spectroscopy over the two separate time domains I and II
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charge transfer structures of aromatic electron donor acceptor complexes leading to electron transfer with the electrophilic Nitrosonium cation
Journal of the American Chemical Society, 1991Co-Authors: Eunkyoung Kim, Jay K. KochiAbstract:Benzene and hexamethylbenzene partake in the rapid formation of unique electron donor-acceptor (EDA) complexes with the Nitrosonium cation, as reflected in the association constants that vary markedly from K=0.5 to 31 000 M −1 , respectively. The increase of Z (the degree of charge transfer) from benzene (0.52) to hexamethylbenzene (0.97) in the charge-transfer complex tracks their increasing proclivity to undergo electron transfer and afford arene cation radicals (ArH •+ ) as reactive intermediates. A general mechanistic formulation based on electron transfer from the charge-transfer complex is developed, in which the facility of the followup reactions (such as fragmentation, cycloreversion, rearrangement, ion-pair annihilation, etc.) of the labile ArH •+ is critical. When the electron transfer is reversible, this 1-electron mechanism is shown not to be readily distinguished from the more conventional electrophilic (2-electron) pathways
A. F. Vanin - One of the best experts on this subject based on the ideXlab platform.
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how is nitric oxide no converted into Nitrosonium cations no in living organisms based on the results of optical and epr analyses of dinitrosyl iron complexes with thiol containing ligands
Applied Magnetic Resonance, 2020Co-Authors: A. F. VaninAbstract:The present work provides theoretical and experimental foundations for the ability of dinitrosyl iron complexes (DNICs) with thiol-containing ligands to be not only the donors of neutral NO molecules, but also the donors of Nitrosonium cations (NO+) in living organisms ensuring S-nitrosation of various proteins and low-molecular-weight compounds. It is proposed that the emergence of those cations in DNICs is related to disproportionation reaction of NO molecules, initiated by their binding with Fe2+ ions (two NO molecules per one ion). At the same time, possible hydrolysis of iron-bound Nitrosonium cations is prevented by the electron density transition to Nitrosonium cations from sulfur atoms of thiol-containing ligands, which are included in the coordination sphere of iron. It allows supposing that iron in iron–nitrosyl complexes of DNICs has a d7 electronic configuration. This supposition is underpinned by experimental data revealing that a half of nitrosyl ligands are converted into S-nitrosothiols (RSNOs) when those complexes decompose, with the other half of those ligands released in the form of neutral NO molecules.
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dinitrosyl iron complexes with thiol containing ligands can suppress viral infections as donors of the Nitrosonium cation hypothesis
Biophysics, 2020Co-Authors: A. F. VaninAbstract:The appropriateness of verification of the possible antiviral effect of dinitrosyl iron complexes with thiol-containing ligands as donors of Nitrosonium cations (NO+) is argued. There is reason to hope that treatment of the human respiratory tract and lungs with sprayed solutions of dinitrosyl iron complexes with glutathione or N-acetylcysteine (NAC) as NO+ donors during COVID-19 infection can initiate S-nitrosylation of cellular proteases and thereby suppress viral infection.
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The Free-Radical Nature of Nitric Oxide Molecules as a Determinant of their Conversion to Nitrosonium Cations in Living Systems
Biophysics, 2020Co-Authors: A. F. VaninAbstract:This paper presents new results that confirm our previous inference that the binuclear form of biologically active dinitrosyl iron complexes (B-DNICs) with thiol-containing ligands (glutathione or N -acetyl-L-cysteine) may act as a donor of Nitrosonium cations, which are responsible for S -nitrosothiol formation during B-DNIC decomposition in acid solutions under both aerobic and anaerobic conditions. The presence of Nitrosonium cations within B-DNICs is determined by the dispropoportionation reaction of free-radical nitric oxide (NO) molecules while binding to Fe^2+ cations (two molecules per one ion) during B-DNIC synthesis. When thiolic ligands are oxidized in DNICs or inactivated by thiol-specific reagents, the Nitrosonium cations released during decomposition of these DNICs at neutral pH values are hydrolyzed and transformed to nitrite anions. A similar transformation occurs when mononuclear DNICs (M-DNICs) with nonthiolic ligands are decomposed at neutral pH values. It has been found that S -nitrosothiol formation in the decomposition of B-DNICs with thiolic ligands at acidic pH values can be inhibited by the presence of a two to threefold excess of free thiol molecules (outside the B-DNIC) with regard to the B-DNIC level. This inhibition is due to the reduction of Nitrosonium cations induced by free thiol molecules and catalyzed by iron ions. The NO molecules that result from the reduction are released from the DNICs. Thus, both forms of DNICs, M and B, that form in living systems can act not only as donors of NO, which is now recognized as one of the universal regulators of metabolic processes, but also as donors of Nitrosonium cations, which initiate S -nitrosation of low- and high-molecular-weight (protein-bound) thiols.
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dinitrosyl iron complexes with thiol containing ligands as donors of Nitrosonium cations suppress viral infections hypothesis
Biofizika, 2020Co-Authors: A. F. VaninAbstract:The importance of exploration of the possible antiviral action of dinitrosyl iron complexes with thiol-containing ligands as donors of Nitrosonium cations (NO+) has been discussed throughout the paper Evidence suggests that inhalation of nebulized dinitrosyl iron complexes with glutathione or N-acetyl-L-cysteine as NO+ donors in a person infected with a virus such as COVID-19 might initiate S-nitrosation of cellular proteases, thereby suppressing viral infection Аргументируется целесообразность проверки возможного противовирусного действия динитрозильных комплексов железа с тиолсодержащими лигандами как донорами катионов нитрозония (NO+) Есть основание надеяться, что ингаляция дыхательных путей и легких человека при COVID-19 инфекции распыленными растворами динитрозильных комплексов железа с глутатионом или N-ацетил-L-цистеином как донорами NO+ может инициировать S-нитрозирование клеточных протеаз и тем самым подавить вирусную инфекцию
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mechanism of inhibition of catalase by nitro and nitroso compounds
Biochemistry, 2008Co-Authors: Yu V Titov, Yu M Petrenko, A. F. VaninAbstract:Dinitrosyl iron complexes (DNIC) with thiolate ligands and S-nitrosothiols, which are NO and NO+ donors, share the earlier demonstrated ability of nitrite for inhibition of catalase. The efficiency of inhibition sharply (by several orders in concentration of these agents) increases in the presence of chloride, bromide, and thiocyanate. The nitro compounds tested—nitroarginine, nitroglycerol, nitrophenol, and furazolidone—gained the same inhibition ability after incubation with ferrous ions and thiols. This is probably the result of their transformation into DNIC. None of these substances lost the inhibitory effect in the presence of the well known NO scavenger oxyhemoglobin. This fact suggests that NO+ ions rather than neutral NO molecules are responsible for the enzyme inactivation due to nitrosation of its structures. The enhancement of catalase inhibition in the presence of halide ions and thiocyanate might be caused by nitrosyl halide formation. The latter protected Nitrosonium ions against hydrolysis, thereby ensuring their transfer to the targets in enzyme molecules. The addition of oxyhemoglobin plus iron chelator o-phenanthroline destroying DNIC sharply attenuated the inhibitory effect of DNIC on catalase. o-Phenanthroline added alone did not influence this effect. Oxyhemoglobin is suggested to scavenge Nitrosonium ions released from decomposing DNIC, thereby preventing catalase nitrosation. The mixture of oxyhemoglobin and o-phenanthroline did not affect the inhibitory action of nitrite or S-nitrosothiols on catalase.
Hassan Valizadeh - One of the best experts on this subject based on the ideXlab platform.
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synthesis of a nitrite functionalized star like poly ionic compound as a highly efficient Nitrosonium source and catalyst for the diazotization of anilines and subsequent facile synthesis of azo dyes under solvent free conditions
Dyes and Pigments, 2015Co-Authors: Hassan Valizadeh, Ashkan Shomali, Jalal Ghorbani, Saeideh NoorsharghAbstract:Abstract Nitrite functionalized star-like poly ionic (NFSPI) compound was synthesized and used as a highly efficient Nitrosonium source and catalyst for the conversion of aniline derivatives to diazonium salts. Azo dyes were prepared via in situ azo-coupling reaction of these diazoniums with active aromatic compounds under solvent-free conditions in very short reaction time in excellent yields. NFSPI plays dual role as a three-dimensional Nitrosonium source and catalyst because of its poly ionic characteristic. The isolated products were confirmed with FT-IR spectrum, 1H-NMR, 13C-NMR spectroscopy and CHNSO analysis. The structure of heterogeneous reagent and catalyst was confirmed by FT-IR spectrum, SEM images, EDX and CHNSO analysis. Yields and reaction times for the synthesis of a variety of products via this procedure were compared with reported values in literature.
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a new nitrite ionic liquid il ono as a Nitrosonium source for the efficient diazotization of aniline derivatives and in situ synthesis of azo dyes
Dyes and Pigments, 2012Co-Authors: Hassan Valizadeh, Ashkan ShomaliAbstract:Abstract A new task-specific nitrite containing ionic liquid derived from the O-nitrosation of N-methyl-N-hydroxybutylimidazolinium chloride was synthesized and used as a source of Nitrosonium ion to affect the efficient diazotization of arylamines. The diazonium salts thus obtained were coupled, using standard experimental procedures, to a range of tertiary anilines, phenols and naphthols to afford the requisite azo dyes in good yield. The diazotization and subsequent azo-coupling generated the related azo dyes at 0–5 °C in short reaction times with a simple experimental procedure.
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nanoparticles of organosilane based nitrite ionic liquid immobilized on silica for the diazotization of aniline derivatives and subsequent synthesis of azo dyes
Dyes and Pigments, 2012Co-Authors: Hassan Valizadeh, Mohammad Amin Amiri, Farideh HosseinzadehAbstract:Abstract Imidazolium based nitrite ionic liquid containing trimethoxysilyl group was prepared from the reaction of N-methylimidazole and (3-chloropropyl) trimethoxysilane. This ionic liquid was immobilized on silica covalently to give nanoparticles with the imidazolium nitrite moiety remaining intact. The diazotization reaction was performed as a model reaction to examine the activity of these nanoparticles as a Nitrosonium source. Excellent performance was exhibited in the diazotization reaction of various aniline derivatives in the presence of HCl under mild heterogeneous conditions (room temperature and short reaction time). In-situ coupling of diazonium salts to a range of tertiary anilines, phenols and naphthols afforded the requisite azo dyes in good yield, using standard experimental procedures.
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new nitrite ionic liquid il ono and nanoparticles of organosilane based nitrite ionic liquid immobilized on silica as Nitrosonium sources for electrophilic aromatic nitrosation
Comptes Rendus Chimie, 2011Co-Authors: Hassan Valizadeh, Mohammad Amin Amiri, Ashkan ShomaliAbstract:Abstract An improved method for the synthesis of nitrosoarenes has been developed using a new nitrite ionic liquid (IL-ONO) and immobilized nitrite ionic liquid. These ionic liquids play as Nitrosonium sources for electrophilic aromatic nitrosation of active aromatics at 0–5 °C. Their action was accomplished in water and the satisfactory results were obtained under the mild conditions in short reaction time.
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bmim no2 h3bo3 as an effective Nitrosonium source for electrophilic aromatic nitrosation under mw promoted solvent free conditions
Comptes Rendus Chimie, 2011Co-Authors: Hassan Valizadeh, Hamid GholipourAbstract:Abstract [Bmim]NO 2 /H 3 BO 3 was used as a Nitrosonium source for the efficient synthesis of nitrosoarenes. The reaction was accomplished under MW irradiation at 60 W in a solventless system. Side processes such as oxidation or dealkylation were not observed during the nitrosation of alkyl phenyl ethers in the presence of this new reagent. The satisfactory results were obtained with very short reaction time, simplicity in the experimental procedure and good to excellent yields.
Peter Mayer - One of the best experts on this subject based on the ideXlab platform.
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cyclometalation of phosphanes at iridium i interplay with intramolecular reductive elimination induced by the strong π acceptor ligands co and no
European Journal of Inorganic Chemistry, 2015Co-Authors: Hanschristian Bottcher, Merlin Junk, Peter Mayer, Wolfgang BeckAbstract:Reaction of [{Ir(μ-Cl)(coe)2}2] (1; coe = cis-cyclooctene) with 4 equiv. of PtBu2Ph in CH2Cl2 at ambient temperature resulted in oxidative addition of one phosphane ligand affording the known cyclometalated IrIII complex [IrCl(H)(PtBu2C6H4-κ2P,C)(PtBu2Ph)] (2) in high yield. Compound 2 exhibits a coordinatively unsaturated five-coordinate 16 VE species, and its reactivity towards strong π-acceptor ligands is investigated. Reaction of 2 with CO resulted in addition of the CO ligand and inversion of cyclometalation to give known IrI complex trans-[IrCl(CO)(PtBu2Ph)2] (3). In a similar manner, 1 reacted with Nitrosonium tetrafluoridoborate affording the new complex salt [IrCl(NO)(PtBu2Ph)2][BF4] (4), which is isoelectronic with 3. Compounds 2 and 4 were characterized by spectroscopic methods as well as by X-ray crystallography confirming their molecular structures.
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structurally characterized ternary u o n compound un4o12 uo2 no3 2 n2o4 or no uo2 no3 3
Inorganic Chemistry, 2005Co-Authors: Margaretjane Crawford, Peter MayerAbstract:The synthesis and characterization of the ternary U-O-N compound NO(+)UO2(NO3)3- (1) using IR and low-temperature and room-temperature Raman spectroscopy as well as 14N and 15N NMR spectroscopy are reported. In addition, solution Raman spectra of compound 1 recorded in various solvents are reported. The structure of compound 1 was determined using single-crystal X-ray diffraction techniques: monoclinic, C2/c, a = 13.3992(4) angstroms, b = 9.9781(4) angstroms, c = 7.6455(2) angstroms, beta = 115.452(2) degrees, V = 922.98(5) angstroms3, Z = 4. Compound 1 is highly moisture-sensitive and must be handled under an inert atmosphere. It reacts with water with the liberation of NO2. For the first time, this important precursor for the synthesis of anhydrous uranyl nitrate could be unambiguously identified and has been shown to be an ionic Nitrosonium salt and not an adduct between uranyl nitrate and dinitrogen tetroxide, UO2(NO3)2.N2O4, as is incorrectly and predominantly cited in the literature.
Dudley R Herschbach - One of the best experts on this subject based on the ideXlab platform.
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high pressure stability transformations and vibrational dynamics of Nitrosonium nitrate from synchrotron infrared and raman spectroscopy
Journal of Chemical Physics, 2003Co-Authors: Yang Song, Maddury Somayazulu, Hokwang Mao, Russell J Hemley, Zhenxian Liu, Dudley R HerschbachAbstract:The properties of Nitrosonium nitrate (NO+NO3−) were investigated following synthesis by laser heating of N2O and N2O4 under high pressures in a diamond anvil cell. Synchrotron infrared absorption spectra of NO+NO3− were measured at pressures up to 32 GPa at room temperature. Raman spectra were obtained at pressures up to 40 GPa at room temperature and up to 14 GPa at temperatures down to 80 K. For both lattice and intramolecular vibrational modes, a smooth evolution of spectral bands with pressure indicates that NO+NO3− forms a single phase over a broad range above 10 GPa, whereas marked changes, particularly evident in the Raman spectra at low temperature, indicate a phase transition occurs near 5 GPa. NO+NO3− could be recovered at atmospheric pressure and low temperature, persisting to 180 K. The Raman and IR spectroscopic data suggest that the NO+NO3− produced by laser heating of N2O followed by decompression may differ in structure or orientational order–disorder from that produced by autoionization ...
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high pressure structure and equation of state study of Nitrosonium nitrate from synchrotron x ray diffraction
Journal of Chemical Physics, 2003Co-Authors: Yang Song, Maddury Somayazulu, Hokwang Mao, Russell J Hemley, Dudley R HerschbachAbstract:Several nitrogen oxide compounds transform to Nitrosonium nitrate (NO+NO3−) under high pressure. In this study, NO+NO3− was synthesized by laser heating of N2O in a diamond-anvil cell and characterized by x-ray diffraction as a function of pressure at room temperature and low temperature. The unit-cell parameters were refined up to 32.2 GPa at 300 K, resulting in a denser structure than reported previously. The pressure-volume relations for NO+NO3− at 300 K were fitted to both Birch-Murnaghan and Vinet equations of state. The analysis indicates that NO+NO3− is denser than other nitrogen-oxygen assemblages, consistent with the conclusion that formation of the ionic species is driven by density rather than entropic effects. The low-temperature x-ray-diffraction data represent the first in situ measurements for this material, revealing consistent structural information and evolutions under pressure. These observations provide additional information on the stability relations and reaction diagram of N2O and N...