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Iron porphyrins and

Professor Mahy received his Ph.D. in 1990 from the University of Paris 6 on a bioinorganic subject dealing with the importance of the complexes with an Fe—N bond in the chemistry of iron-porphyrin and hemoproteins. [Pg.352]

Picosecond Excited-State Relaxation of Some Iron Porphyrins and Hemoproteins... [Pg.168]

Experimental Results for Iron Porphyrins and Comparison with Theory... [Pg.230]

Buschmann, J., W. Angst, and R. P. Schwarzenbach, Iron porphyrin and cysteine mediated reduction of ten polyhalogenated methanes in homogeneous aqueous solution Product analyses and mechanistic considerations , Environ. Sci. Technol., 33, 1015-1020 (1999). [Pg.1218]

There have been very few reports of the Raman spectra of spin-equilibrium complexes. In one experiment the presence of both high-spin and low-spin isomers of an iron(II) Schiff base complex was observed by the resonance Raman spectra of the imine region (11). The temperature dependence of the spectra was recorded for both solid and solution samples. Recently differences were described in the resonance Raman spectra of four- and six-coordinate nickel(II) porphyrin complexes which undergo coordination-spin equilibria. These studies are extensions of a considerable literature on spin state effects on the Raman spectra of iron porphyrins and hemes. There are apparently no reports of attempts to use time-resolved Raman spectra for dynamics experiments. [Pg.13]

The structure of iron(II) octaethylchlorin shows the iron and four nitrogen atoms to be rigorously planar, but the rest of the chlorin macrocycle to be significantly S4 ruffled.732 Hydroporphyrins intrinsically have larger cores than porphyrins, but the distortion from planarity leads to a reduction in core size and shorter metal-nitrogen distances. The enhanced ability of hydroporphyrins to undergo distortion so as to adjust their core size in response to the size of the metal may be responsible for the differences between iron porphyrins and hydroporphyrins.733... [Pg.625]

Figure 14.5 Shielding of an iron porphyrin and thiolate cluster cores within dendrimers. Figure 14.5 Shielding of an iron porphyrin and thiolate cluster cores within dendrimers.
In Mb, heme is located in the heme pocket via multiple noncovalent interactions such as Fe-His coordination, hydrophobic contacts with several nonpolar amino acid residues, and hydrogen bonding between heme propionates and polar amino acids (69). Therefore, the hemin can be easily removed from the heme pocket under acidic conditions to give apomyoglobin (apoMb) (70, 71). Over the past three decades, a variety of artificial iron porphyrins and porphyrinoids have been incorporated into the apoprotein to reconstitute the... [Pg.473]

Schaefer W, Harris T, Guengerich F. Characterization of the enzymatic and non-enzymatic peroxidative degradation of iron porphyrins and cytochrome P-450 heme. Biochem J 1985 24 3254—3263. [Pg.538]

In summary, the electrochemical results indicate that the alkyl-metal bond-formation free energies range from 54 to 146 kJ mol-1 for iron porphyrins and from 84 to 159 kJ mol-1 for cobalt porphyrins. The maximum bond energies are for primary alkyl groups bonded to [(MeO)4TPP]Con and (OEP)Fen porphyrins. The porphyrin dianions [(porT)nFe and (porr)nCo ] facilitate the reduction of C02 to CO via the transient formation of a metal-carbon bond [(por7)M—C(0)0- — AGBF > 50 kJ mol-1 for iron porphyrins]. Thus, iron and cobalt porphyrins are especially effective electrocatalysts for the reduction of C02 ... [Pg.491]

Extensive RR studies on iron porphyrins and heme proteins (9) have shown that all porphyrin core frequencies give negative linear correlations with the core size of the Fe center, and the slopes of these correlations are roughly... [Pg.215]

Other Systems. Alkyl Thiols. The reduction of hemin with ethane-thiol has been suggested to occur by a free radical mechanism on the basis of product analysis (II). The reaction of n-hexanethiol with TPPFeCl in DMSO carried out in the ESR cavity gives rise to the signal illustrated in Figure 7. These are preliminary results, and the spectrum is of poor quality and probably reflects some saturation from the low steady-state concentration of the radical. Nevertheless the signal only appears during the autoreduction of the iron porphyrin and again indicates that the autoreduction occurs by a free radical pathway. [Pg.220]

The iron porphyrins and related compounds constitute an extremely important class of coordination complex due to their chemical behaviour and involvement in a number of vital biological systems. Over recent years a vast amount of work on them has been published. Chapter 21.1 deals with the general coordination chemistry of metal porphyrins, hydroporphyrins, azaporphyrins, phthalocyanines, corroles, and corrins. Low oxidation state iron porphyrin complexes are discussed in Section 44.1.4.5 and those containing nitric oxide in Section 44.1.4.7, while a later section in this chapter (44.2.9.2) is mainly concerned with iron(III) and higher oxidation state porphyrin complexes. Inevitably however, a considerable amount of information on iron(II) complexes is contained in that section as well as in Chapter 21.1. Therefore in order to prevent excessive duplication, the present section is restricted to highlighting some of the more important aspects of the coordination chemistry of the iron(II) porphyrins while the related unusually stable phthalocyanine complexes are discussed in the previous section. [Pg.1266]

Figure 2 Possible oxidation and spin states of iron porphyrins and the d orbital configurations expected in each case. AU of these states (excluding high-spin d, which is not included in the figure) have been observed for iron porphyrins, and are discussed in this article. In addition, the spin-admixed 5 = 3/2,5/2 state of Fe " and the alternative orbital configuration for low-spin Fe , with dxy higher in energy than dxi,dyz are also discussed... Figure 2 Possible oxidation and spin states of iron porphyrins and the d orbital configurations expected in each case. AU of these states (excluding high-spin d, which is not included in the figure) have been observed for iron porphyrins, and are discussed in this article. In addition, the spin-admixed 5 = 3/2,5/2 state of Fe " and the alternative orbital configuration for low-spin Fe , with dxy higher in energy than dxi,dyz are also discussed...
As part of the work on model heme FeNO complexes, mechanistic studies on the reversible binding of nitric oxide to metmyoglobin and water soluble Fe, Co and Fe porphyrin complexes in aqueous solution, ligand-promoted rapid NO or NO2 dissociation from Fe porphyrins, reductive nitrosylation of water-soluble iron porphyrins, activation of nitrite ions to carry out O-atom transfer by Fe porphyrins, demonstration of the role of scission of the proximal histidine-iron bond in the activation of soluble guanylyl cyclase through metalloporphyrin substitution studies, reactions of peroxynitrite with iron porphyrins, and the first observation of photoinduced nitrosyl linkage isomers of FeNO heme complexes have been reported. [Pg.2136]

Work on the redox chemistry of iron porphyrins and their protein adducts deals mainly with two problems, namely the electron transfer, which is mediated by the FeII/Fe111 couple in cytochromes, and the partial reduction of the oxygen molecule to the superoxide anion or to a peroxo bridge between two iron porphyrins. The work on isolated iron porphyrins will be summarized in this section, whereas the hemoproteins will be covered in Section VI. [Pg.27]

Biomimetic oxidation catalysis has largely focused on complexes with planar tetradentate ligands such as manganese or iron porphyrins and related macrocyclic trans-chelates[5]. There is considerable interest in the synthesis of multinuclear metal complexes since these molecules might be useful as building block for magnetic molecular materials[6] and model compounds for understanding the properties of metalloproteins[7]. [Pg.845]

Oxidation and spin states of iron porphyrins and their bioiogicai occurrences. [Pg.203]

Cytochrome c oxidase is the terminal member of the respiratory chain in all animals and plants, aerobic yeasts, and some bacteria." " This enzyme is always found associated with a membrane the inner mitochondrial membrane in higher organisms or the cell membrane in bacteria. It is a large, complex, multisubunit enzyme whose characterization has been complicated by its size, by the fact that it is membrane-bound, and by the diversity of the four redox metal sites, i.e., two copper ions and two heme iron units, each of which is found in a different type of environment within the protein. Because of the complexity of this system and the absence of detailed structural information, spectroscopic studies of this enzyme and comparisons of spectral properties with 02-binding proteins (see Chapter 4) and with model iron-porphyrin and copper complexes have been invaluable in its characterization. [Pg.267]

Before we consider the reactions of cytochrome c oxidase with dioxygen, it is instructive to review the reactions of dioxygen with iron porphyrins and cop-... [Pg.273]

N. Nakamura, and Y. Naruta (2001). Synthesis and characterization of alkanethiolate-coordinated iron porphyrins and their dioxygen adducts as models for the active center of cytochrome P450 Direct evidence for hydrogen bonding to bound dioxygen. J. Am. Chem. Soc. 123, 1133-1142. [Pg.230]


See other pages where Iron porphyrins and is mentioned: [Pg.258]    [Pg.111]    [Pg.385]    [Pg.169]    [Pg.420]    [Pg.619]    [Pg.66]    [Pg.70]    [Pg.92]    [Pg.337]    [Pg.300]    [Pg.211]    [Pg.386]    [Pg.111]    [Pg.2148]    [Pg.5847]    [Pg.6255]    [Pg.6263]    [Pg.31]    [Pg.440]    [Pg.82]    [Pg.62]    [Pg.2109]    [Pg.2135]   
See also in sourсe #XX -- [ Pg.17 , Pg.344 , Pg.346 , Pg.355 , Pg.356 , Pg.357 , Pg.359 , Pg.375 ]




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