42034-08-2Relevant academic research and scientific papers
Nitric oxide release via oxygen atom transfer from nitrite at copper(ii)
Sakhaei, Zeinab,Kundu, Subrata,Donnelly, Jane M.,Bertke, Jeffery A.,Kim, William Y.,Warren, Timothy H.
, p. 549 - 552 (2017)
Nitric oxide is a vital signaling molecule that controls blood flow and oxygenation and nitrite serves as an important reservoir for nitric oxide in biology. While copper containing enzymes are known to reduce nitrite to nitric oxide, herein we report a new pathway to release nitric oxide via oxygen atom transfer from nitrite at a copper(ii) site.
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.
Structural and oxo-transfer reactivity differences of hexacoordinate and pentacoordinate (nitro) (tetraphenylporphinato)cobalt(III) derivatives
Goodwin,Bailey,Pennington,Rasberry,Green,Shasho,Yongsavanh,Echevarria,Tiedeken,Brown,Fromm,Lyerly,Watson,Long,De Nitto
, p. 4217 - 4225 (2001)
The oxo-transfer catalyst (nitro)(pyridyl)cobalt(III) tetraphenylporphyrin has been reinvestigated by substitution of the distal pyridine ligand with 4-N,N-dimethylaminopyridine and 3,5-dichloropyridine. Differences in their structures and in the reactivity of the compounds toward catalytic secondary oxo transfer were investigated by FT-IR and UV-visible spectroscopy, cyclic voltammetry, X-ray diffraction, semiempirical calculations, and reactions with alkenes in dichloromethane solution. Very modest differences in the hexacoordinate compounds' structures were predicted and observed, but the secondary oxo-transfer reactivity at the nitro ligand varies markedly with the basicity of the pyridine ligand and the position of the coordination equilibrium. Oxo transfer occurs rapidly through the pentacoordinate species (nitro)cobalt(III) tetraphenylporphyrin that is generated by dissociation of the pyridine ligand and therefore is strongly related to the Hammett parameters of these nitrogenous bases. The reactive pentacoordinate species CoTPP(NO2) can be generated in solution by addition of lithium perchlorate to (py)CoTPP(NO2) by Lewis acid-base interactions or more simply by using the weaker Lewis base Cl2py instead of py as the distal ligand. In contrast to pentacoordinate (nitro)iron porphyrins, disproportionation reactions of CoTPP(NO2) compound are not evident. This pentacoordinate derivative, CoTPP(NO2), is reactive enough to stoichiometrically oxidize allyl bromide in minutes. Preliminary catalytic oxidation reaction studies of alkenes also indicate the involvement of both radical and nonradical oxo-transfer steps in the mechanism, suggesting formation of a peroxynitro intermediate in the reaction of the reduced CoTPP(NO) with O2.
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.
Photochemistry of nitrosyl metalloporphyrins: Mechanisms of the photoinduced release and recombination of NO
Zavarine, Igor S.,Kini, Abhay D.,Morimoto, Bruce H.,Kubiak, Clifford P.
, p. 7287 - 7292 (1998)
A series of substituted nitrosylmetalloporphyrins of the type M(NO)(meso-tetra(p-X)phenylporphyrin) (M = Co, Mn; X = H, NO2, OMe) were prepared and studied by laser flash photolysis. The kinetics of the recombination reactions between the metalloporphyrins and NO in THF were examined. The recombination mechanism appears to be more complicated than the simple second-order process previously reported. Out-of-plane puckering of the porphyrin ring immediately after denitrosylation is one possible explanation. Kinetic experiments and NO transfer studies between manganese and cobalt porphyrins suggest that these compounds exist in equilibrium with NO in solution. Varying the substituents in the phenyl ring of the tetraphenylporphyrin ligand has little effect on rates of recombination with NO.
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.
Interaction of Nitrogen Oxides with Sublimed Layers of (meso-Tetraphenylporphyrinato)cobalt(II); IR Evidence of Oxo-Transfer from (Nitro)porphyrinatocobalt(III) to Free Nitric Oxide
Kurtikyan, Tigran S.,Mardyukov, Arthur N.,Goodwin, John A.
, p. 8489 - 8493 (2003)
Interaction of a low-pressure NO2 with sublimed layers of (meso-tetraphenylporphyrinato)cobalt(II) (Co(TPP)) leads to formation of 5-coordinate nitro complex Co(III)(TPP)(NO2). Upon exposure of these layers to pyridine vapors, the fast reaction with formation of 6-coordinate nitro-pyridine porphyrins (Py)Co(III)(TPP)(NO2) occurs. By means of IR spectroscopy and use of nitrogen oxide isotopomers, it is shown that an oxo-transfer reaction occurs from 5-coordinate species to free nitric oxide (NO) while the 6-coordinate complex is rather inert. It is also demonstrated that the stepwise addition of low-pressure NO2 to nitrosyl complex Co(TPP)(NO) leads to formation of the nitro complex most likely by an exchange reaction.
Nitric oxide deligation from nitrosyl complexes of two transition metal porphyrins: A photokinetic investigation
Morlino, Elisabeth A.,Rodgers, Michael A. J.
, p. 11798 - 11804 (1996)
The results of an investigation of the ultrafast dynamics of photoinduced deligation in two transition metalloporphyrin-nitrosyl complexes, TPPFe(II)NO and TPPCo(II)NO, in conjuction with the results of an energy transfer study lead to the conclusion that the difference in the denitrosylation yields (?(NO) = 0.5 for TPPFe(II)NO and ?(NO) = 1.0 for TPPCo(II)NO is the result of energy partitioning in the upper excited states of the porphyrin. The energy transfer study yielded the energies of the metal centered states, believed to be of CT(π,d(z)2) nature, and of the localized porphyrin triplet states. The CT states in the two complexes were found to lie at similar energies (TPPFe(II)NO 8650 cm-1 and TPPCo(II)NO 8900 cm-1); however, the localized porphyrin triplet states were found to be at 16200 cm-1 in TPPFe(II)NO and 14700 cm-1 in TPPCo(II)NO. This difference in energies of the respective triplet states facilitates efficient intersystem crossing in the excited state deactivation of TPPFe(II)NO, but does not allow any triplet formation in TPPCo(II)NO. The direct excitation studies revealed that intersystem crossing in TPPFe11NO occurs with a rate constant of 7.3 x 1011 s-1 to yield a localized porphyrin triplet state that absorbs maximally at 450 nm. This state then relaxes back to the ground state without the loss of NO. Only those excited states that relax via the CT state result in loss of NO. The direct excitation studies yielded no evidence for intersystem crossing in the deactivation of the electronically excited singlet state of TPPCo(II)NO, hence all of the energy deposited in the initial photoexcitation step results in NO loss. The lifetimes and spectral characteristics of the other excited states involved in deactivation of these transition metalloporphyrin-nitrosyl complexes will be discussed.
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.
Thionitrite and Perthionitrite in NO Signaling at Zinc
Bertke, Jeffery A.,Hosseininasab, Valiallah,Warren, Timothy H.
supporting information, p. 21184 - 21188 (2021/08/25)
NO and H2S serve as signaling molecules in biology with intertwined reactivity. HSNO and HSSNO with their conjugate bases ?SNO and ?SSNO form in the reaction of H2S with NO as well as S-nitrosothiols (RSNO) and nitrite (NO2?) that serve as NO reservoirs. While HSNO and HSSNO are elusive, their conjugate bases form isolable zinc complexes Ph,MeTpZn(SNO) and Ph,MeTpZn(SSNO) supported by tris(pyrazolyl)borate ligands. Reaction of Na(15-C-5)SSNO with Ph,MeTpZn(ClO4) provides Ph,MeTpZn(SSNO) that undergoes S-atom removal by PEt3 to give Ph,MeTpZn(SNO) and S=PEt3. Unexpectedly stable at room temperature, these Zn-SNO and Zn-SSNO complexes release NO upon heating. Ph,MeTpZn(SNO) and Ph,MeTpZn(SSNO) quickly react with acidic thiols such as C6F5SH to form N2O and NO, respectively. Increasing the thiol basicity in p-substituted aromatic thiols 4?XArSH in the reaction with Ph,MeTpZn(SNO) turns on competing S-nitrosation to form Ph,MeTpZn-SH and RSNO, the latter a known precursor for NO.
