Metalloporphyrin components

Isocyanides bearing ammonium side-chains 51 and 52 have been polymerized in the presence of nickel catalysts [72, 73]. The amphiphilic isocyanide 51 forms vesicles on dispersion in water. The isocyano groups located in the vesicle bilayers were polymerized by nickel capronate to form polymerized vesicles. The isocyanide 51 was also used in the preparation of polymerized vesicles containing metalloporphyrin components within the bilayer membrane [74]. The redox behavior of this membrane-bound cytochrome P-450 mimic has been investigated in detail. In addition to those bearing cationic side chains, isocyanides 53 and 54 bearing zwitterionic side chains were successfully used [75]. 

Fullerenes are spontaneously attracted to porphyrins and metalloporphyrins. The palladium-linked m-pyridyl dimer (shown in Figure 42) has a high binding constant in solution. Addition of C60 or C70 to solutions of these palladium-linked bis-porphyrins gave complexes that were chromatographically distinct from their individual components. This indication of tight binding was also seen in MALDI mass spectra.517... 

Metal nanoparticles have extraordinary size-dependent optical properties, not present in the bulk metal and have, consequently, been the subject of intense research during the past decade or so.27 Attention has recently focused on functionalising colloidal nanoparticles with molecular recognition components for potential sensing applications.28,29,30 We have prepared a new amido-disulfide functionalised zinc metalloporphyrin (8) which was self-assembled on to gold nanoparticles to produce a novel anion-selective optical sensing system (9) (Scheme 3).4... 

The results from the publications mentioned are of interest because they can help in the creation of effective catalytic systems containing porphyrins, which combine functions typical of multienzyme systems. The task in hand is the possible synthesis of bifunctional catalysts based on metalloporphyrin systems, when with the help of manganese porphyrins, for example, or SOD mimic, hydrogen peroxide is accumulated in the system. Afterwards, the accumulated hydrogen peroxide is used in oxidation reactions of various substrates with iron porphyrin components of the catalyst. 

In summary, the electrochemistry of organometallic and metalloporphyrins is dominated by synergistic electron transfer of extramolecular solution components (H20, 02, electrophiles, and nucleophiles). This provides a convenient means for evaluation of the molecular activation (catalytic) properties of these important metal-centered systems. Only in the case of iron (II)- and cobalt(II)-... 

The microemulsion components, particularly the nature of the oil, has been shown to have a dramatic effect on the interaction of metal ions in the microdroplet Interfaclal region. In particular, the change from benzene to mineral oil causes a change in the quinoline dependence of the rate of metalloporphyrin formation and a 0.9 volt shift in copper(II) half- ave potential. The... 

Tetra(4-pyridyl) porphyrin (TPyP) metalloligands also were explored as potential MOF constituents. It is of more than passing interest that TPyPs are often capable of self-association via bonding of the pyridyl nitrogens to the coordina-tively unsaturated central metal of another porphyrin molecule. Several research groups have made an active study of such stmctures (111-117). However, because these coordination polymers tend to be formed from a single molecular component, rather than having the metalloporphyrin bound to a secondary metal center or SBU, they will be omitted from further discussion here. 

Hydrogen producing systems employing metalloporphyrin sensitizers have usually consisted of the same components as systems employing [Ru(bipy)3] as sensitizer, that is EDTA and... 

The limited extent of charge transfer interaction between the exciplex components in the nonpolar benzene solutions is Indicated by plots of the logarithm of kq, the observed rate constant for the quenching of the metalloporphyrin triplet, versus the quencher electrochemical reduction potential. Although the slopes of such plots were linear for the nitroaromatics and for the chloro compounds, the slopes differed for the two groups of... 

It has been found that in two component systems zinc (II) porphyrin-ligand coordination properties of the metalloporphyrins increase in the following order ZnTPhPelectron effects of peripheral substitutes. In three component systems zinc (II) porphyrin-ligand-benzene the mentioned above properties change in the following order ZnPP>ZnDP>ZnHP>ZnTPhP and are inversely proportional to an ability of the macrocycle to 7r-7i-interactions with benzene. Thus, the new approach to molecular recognition based on specific salvation 71-71-interactions is demonstrated on example of znc (II) porphyrins. 

There is an EXAFS report on the hydroxylase component of the MMO from Methylobacterium CRL-26 that shows an average Fe-L distance of 1.92 A and an Fe-Fe separation of 3.05 A (42). The tack of a short Fe-p,-0 bond is consistent with the apparent absence of an oxo bridge based on other techniques, while the presence of a Fe scatterer at 3.05 A corroborates the dinuclear nature of the site. However, the apparent lower purity of the sample as indicated by the observ ation of metalloporphyrin-like absorption features in the visible spectrum and the later report by Ericson et al. (52) that MMO from M. capsulatas (Bath) is photoreduced in the synchrotron beam raise doubts about the reliability of these results. 

The average Ni/V ratio for the three oil components was 15.2, and this value was used to calculate a weighted extinction coefficient used for all metalloporphyrin determinations. 

Zn, Hg, Co, Cr and Ni. Examination of the absorption spectra of the methanol-soluble, resin, and asphaltene fractions of the oil showed the presence of porphyrin complexes in all fractions. Liquid chromatography on silica and alumina was used to separate the metalloporphyrins in the low-molecular fractions of the three oil components. Only Ni porphyrins and very small amounts of V porphyrins were identified in the chromatographic fractions. The absorption spectrum of the separated Ni porphyrins corresponds to Ni deoxophyl-... 

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