42034-08-2Relevant articles and documents
Nitrosylcobalt(II) tetraphenylporphinate: Femtosecond and longer studies of the dynamics of NO loss
Morlino, Elisabeth A.,Walker II, Larry A.,Sension, Roseanne J.,Rodgers, Michael A. J.
, p. 4429 - 4430 (1995)
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Mechanism and driving force of NO transfer from S-nitrosothiol to cobalt(II) porphyrin: A detailed thermodynamic and kinetic study
Zhu, Xiao-Qing,Zhang, Jian-Yu,Cheng, Jin-Pei
, p. 592 - 600 (2007)
The thermodynamics and kinetics of NO transfer from S- nitrosotriphenylmethanethiol (Ph3CSNO) to a series of α,β,γ,δ-tetraphenylporphinatocobalt(II) derivatives [T(G)PPCoII], generating the nitrosyl cobalt atom center adducts [T(G)PPCoIINO], in benzonitrile were investigated using titration calorimetry and stopped-flow UV-vis spectrophotometry, respectively. The estimation of the energy change for each elementary step in the possible NO transfer pathways suggests that the most likely route is a concerted process of the homolytic S-NO bond dissociation and the formation of the Co-NO bond. The kinetic investigation on the NO transfer shows that the second-order rate constants at room temperature cover the range from 0.76 × 104 to 4.58 × 104 M-1 s-1, and the reaction rate was mainly governed by activation enthalpy. Hammett-type linear free-energy analysis indicates that the NO moiety in Ph3CSNO is a Lewis acid and the T(G)PPCoII is a Lewis base; the main driving force for the NO transfer is electrostatic charge attraction rather than the spin-spin coupling interaction. The effective charge distribution on the cobalt atom in the cobalt porphyrin at the various stages, the reactant [T(G)PPCoII], the transition-state, and the product [T(G)PPCoIINO], was estimated to show that the cobalt atom carries relative effective positive charges of 2.000 in the reactant [T(G)PPCoII], 2.350 in the transition state, and 2.503 in the product [T(G)PPCoIINO], which indicates that the concerted NO transfer from Ph3CSNO to T(G)PPCoII with the release of the Ph3CS? radical was actually performed by the initial negative charge (-0.350) transfer from T(G)PPCoII to Ph3CSNO to form the transition state and was followed by homolytic S-NO bond dissociation of Ph3CSNO with a further negative charge (-0.153) transfer from T(G)PPCoII to the NO group to form the final product T(G)PPCoIINO. It is evident that these important thermodynamic and kinetic results would be helpful in understanding the nature of the interaction between RSNO and metal porphyrins in both chemical and biochemical systems.
Synthesis, Characterization, and Spectroelectrochemistry of Cobalt Porphyrins Containing Axially Bound Nitric Oxide
Richter-Addo, George B.,Hodge, Shelly J.,Yi, Geun-Bae,Khan, Masood A.,Ma, Tianshu,Van Caemelbecke, Eric,Guo, Ning,Kadish, Karl M.
, p. 6530 - 6538 (1996)
Several cobalt nitrosyl porphyrins of the form (T(plm-X)PP)Co(NO) (plm-X = p-OCH3 (1), p-CH3 (2), m-CH3 (3), p-H (4), m-OCH3 (5), p-OCF3 (6), p-CF3 (7), p-CN (8)) have been synthesized in 30-85percent yields by reaction of the precursor cobalt porphyrin with nitric oxide. Compounds 1-7 were also prepared by reaction of the precursor cobalt porphyrin with nitrosonium tetrafluoroborate followed by reduction with cobaltocene. Compounds 1-8 have been characterized by elemental analysis, IR and 1H NMR spectroscopy, mass spectrometry, and UV-vis spectrophotometry. They are diamagnetic and display VNO bands in CH2Cl2 between 1681 and 1695 cm-1. The molecular structure of 1, determined by a single-crystal X-ray crystallographic analysis, reveals a Co-N-O angle of 119.6(4)°. Crystals of 1 are monoclinic, P2/c, with a = 15.052(1) A?, b = 9.390(1) A?, c = 16.274(2) A?, β = 111.04(1)°, V = 2146.8(4) A?3, Z = 2, T = 228(2) K, D(calcd) = 1.271 g cm-3, and final R1 = 0.0599 (wR2 = 0.1567, GOF = 1.054) for 3330 observed reflections with I ≥ 2σ(I). Cyclic voltammetry studies in CH2Cl2 reveal that compounds 1-7 undergo two reversible oxidations and two reversible reductions at low temperature. This is not the case for compound 8, which undergoes two reversible reductions but an irreversible oxidation due to adsorption of the oxidized product onto the electrode surface. Combined electrochemistry-infrared studies demonstrate that each of the compounds 1-7 undergoes a first oxidation at the porphyrin π ring system and a first reduction at either the metal center or the nitrosyl axial ligand. The formulation for the singly oxidized products of compounds 1-7 as porphyrin π-cation radicals was confirmed by the presence of bands in the 1289-1294 cm-1 region (for compounds 1-5), which are diagnostic IR bands for generation of tetraarylporphyrin π-cation radicals.
Physicochemical Factors That Influence the Deoxygenation of Oxyanions in Atomically Precise, Oxygen-Deficient Vanadium Oxide Assemblies
Petel, Brittney E.,Matson, Ellen M.
, p. 6855 - 6864 (2021)
Here, we report our findings related to the structural and electronic considerations that influence the rate of oxygen-atom transfer (OAT) to oxygen-deficient polyoxovanadate alkoxide (POV-alkoxide) clusters ([V6O6(OC2H5)12]nn = 1-, 0, 1+). A comparison of the reaction times required for the reduction of nitrogen-containing oxyanions (NOx-, x = 2, 3) by the POV-ethoxide cluster in its anionic (1-V6O61-VIIIVIV5), neutral (4-V6O60VIIIVIV4VV), or cationic (6-V6O61+VIIIVIV3VV2) charge state reveals that OAT is significantly influenced by three factors: (1) ion-pairing interactions between the POV-alkoxide and the negatively charged oxyanion; (2) oxidation states of remote vanadyl ions in the Lindqvist assembly; (3) the steric bulk surrounding the coordinatively unsaturated VIIIion. This work provides atomic-level insight related to structure-function relationships that govern the rate of OAT at metal oxide surfaces using polyoxometalate clusters as molecular models.
Spectroelectrochemical Characterization of Substituted Cobalt Nitrosyl Porphyrins
Kini, Abhay D.,Washington, John,Kubiak, Clifford P.,Morimoto, Brace H.
, p. 6904 - 6906 (1996)
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Adducts of nitric oxide with cobaltous tetraphenylporphyrin and phthalocyanines: Potential nitric oxide sorbents
Owens, John Wesley,Perry, Mildred,Seybert, David W.
, p. 1 - 7 (1998)
Cobaltous tetraphenylporphyrin (Co(II)TPP) andcobaltous phthalocyanine (Co(II)Pc) complexes were studied in a variety of solvents, including water. The imidazole and nitrosyl adducts were synthesized and characterized by UV-Vis spectrophotometry and electron spin resonance spectroscopy. The imidazole adducts were subsequently exposed to nitric oxide to study the competitive interactions between nitrosyl and imidazole ligands in these cobaltous compounds. This is important, since it has been suggested that aqueous solutions of cobaltous porphyrins and phthalocyanines can serve as denitrification agents when bound to an immobilized imidazole modified silica gel (IMSG) substrate. Our results indicate that while nitric oxide binds both Co(II)TPP and Co(II)Pc in organic solvents in the absence of a bound imidazole ligand, it will not bind when imidazole is axially bound to the cobalt ion. Neither Co(II)TPP nor Co(II)Pc are water soluble and both will dimerize in water. A water soluble NO sorbent which does not dimerize in water would be ideal for removing NO from flue gas streams. The Co(II)PcTs(IMSG) appears to meet these requirements. Preliminary results indicate that aqueous suspensions of Co(II)PcTs(IMSG) are capable of NO removal from a gas stream passed through these suspensions and may thus be suitable candidates for further development as NO sorbents for NOx abatement.
Lewis Acid Coordination Redirects S-Nitrosothiol Signaling Output
Bakhoda, Abolghasem,Bertke, Jeffery A.,Hosseininasab, Valiallah,McQuilken, Alison C.,Timerghazin, Qadir K.,Warren, Timothy H.
supporting information, p. 10854 - 10858 (2020/04/27)
S-Nitrosothiols (RSNOs) serve as air-stable reservoirs for nitric oxide in biology. While copper enzymes promote NO release from RSNOs by serving as Lewis acids for intramolecular electron-transfer, redox-innocent Lewis acids separate these two functions
Crystal-facet-dependent denitrosylation: Modulation of NO release from S-nitrosothiols by Cu2O polymorphs
Ghosh, Sourav,Roy, Punarbasu,Prasad, Sanjay,Mugesh, Govindasamy
, p. 5308 - 5318 (2019/05/29)
Nitric oxide (NO), a gaseous small molecule generated by the nitric oxide synthase (NOS) enzymes, plays key roles in signal transduction. The thiol groups present in many proteins and small molecules undergo nitrosylation to form the corresponding S-nitrosothiols. The release of NO from S-nitrosothiols is a key strategy to maintain the NO levels in biological systems. However, the controlled release of NO from the nitrosylated compounds at physiological pH remains a challenge. In this paper, we describe the synthesis and NO releasing ability of Cu2O nanomaterials and provide the first experimental evidence that the nanocrystals having different crystal facets within the same crystal system exhibit different activities toward S-nitrosothiols. We used various imaging techniques and time-dependent spectroscopic measurements to understand the nature of catalytically active species involved in the surface reactions. The denitrosylation reactions by Cu2O can be carried out multiple times without affecting the catalytic activity.
