Manganese tetra porphyrin

Manganese nitrosyl porphyrins [215] are considered good models for the iron-nitric oxide analogs, which are relatively unstable but very vital to many biological operations. A six-coordinate manganese nitrosyl porphyrin of the form (por)Mn(NO)(L), where por can be TTP (TTP = tetra(4-methylphenyl)porphine) and L = piperidine, methanol, 1-methyhmidazole, has been prepared [216] in moderate yields by the reductive nitrosylation of the (por)MnCl complex with NO in piperidine. The crystal structures of these compounds give indication of a linear Mn-NO bond [215]. 

Certain manganese porphyrins adsorbed on silica or alumina, or intercalated in different mineral matrices such as montmorillonite, are also very efficient in alkane hydroxylation.150 151 Alcohol yields and alcohol ketone ratios are remarkably higher than those obtained with the corresponding soluble manganese porphyrins. Manganese tetra(4-Al-methylpyridiniumyl)porphyrin supported on montmorillonite, for instance, is efficient in the hydroxylation of compounds of low reactivity such as n-pentane and n-heptane.151... 

The reactions of peroxidases have been mimicked, using synthetic iron(III) and manganese(III) porphyrins catalysts as models for the haem prosthetic group, and these simplified systems have been used to obtain mechanistic information about the oxidations. " At York we have been investigating the oxidation of phenols by oxoiron(IV) and oxomanganese(IV) porphyrin models for HRP II in aqueous solution. This research has shown that, at pH 7.6, oxidation proceeds by hydrogen atom abstraction by the oxometallo(IV) species from the phenol rather than electron transfer from the phenolate anion. Preliminary studies with commercial azo dyes has revealed that these are also substrates for oxoiron(IV)porphyrins. In this paper we report the results from our investigations of the mechanism of oxidation of l-phenylazo-2-naphthol-6-sulfonates by oxoiron(IV) tetra(2,6-dichloro-3-sulfonatophenyl)porphyrin (1) in aqueous solution. 

With regard to the pressure effects, we have, as usual, been interested in systems that are not simple. One system we have been looking at involves water-soluble porphyrins. Actually, the only reactions we have studied thus far involve the iron(III) and manganese(III) tetra(4-N-methylpyridyl)porphyrin complexes. These complexes are in the form of tosylate salts, which causes some problems. The rate constants are on the order... 

In the case of manganese porphyrin catalyzed epoxidations, the axial ligands have been used alone or together with other additives like carboxylic acids (Banfi and coworkers) and soluble bases (Johnstone and coworkers). For example, Mansny and coworkers showed that in the presence of imidazole, 2-methylimidazole or 4-imidazole chloromanganese(tetra-2,6-dichlorophenylporphyrin) catalyzes the epoxidation of varions aUtenes including 1-alkenes by Under these conditions alkene conversion... 

The extremely hindered manganese(III) tetra(2,4,6-triphenylphenyl)porphyrin acetate [Mn(TTPPP)OAc], in contrast, gives the less hindered 3,3-dimethylbutane-l-ol with exceptionally high selectivity. Hindered metalloporphyrins also exhibit an increasing reactivity in the oxidation of the -1 CH2 site in straight-chain alkanes.148... 

Certain robust manganese porphyrins [e.g., manganese(IH) tetra(2, 6 -dichloro-pheny])porphyrin chloride] are able to catalyze stereoselective epoxidations, when applied in the presence of imidazole324-327 or other heterocyclic nitrogen bases.326 NaI04324 or even H202325-327 can be used as oxidant. 

The phthalocyanine complexes of manganese have been studied for many years ° The most recent work has established the formation of an rf dioxygen complex on oxygenation of [Mn(Pc)] in N,N-dimethylacetamide solution and a similar result has been obtained for a tetra-sulphonated phthalocyanine derivative The porphyrin complex Mn(TPP)02 was assigned an rf structure on the basis of E.P.R. data and this assignment has recently been supported by infra-red data using 02 Schiff base complexes of Mn(II) were reported to form dinuclear rf complexes on oxygenation in... 

The synthesis of manganese acetate tetra-p-aminophenylporphyrinate (MnAc-TAPhP) chemically immobilized on different polymeric supports was carried out, and its catalytic activity during cholesterol oxidation by molecular oxygen was studied [107]. Soluble porphyrin-containing polymers were obtained by copolymerization of methacrylate or 4-vinylpyridine with the product of interaction of acrylic acid chloride with MnAcTAPhP. Cholesterol oxidation was performed in a 1 1 mixture of ethanol and chloroform. The effective rate constants, / eff, were determined from the initial rate of product formation. 

Di- and tetra-9,9 -spirobifiuorene porphyrins 105-107, shown in Fig. 39, were synthesized by Poriel et al. [22]. These compounds show a hindered rotation about the porphyrin-spiro bond, which leads to the occurrence of at-ropisomers. Manganese and iron complexes of these spiro-porphyrins have been studied with respect to their properties as oxidation catalysts in heterogeneous catalysis [133,134]. 

One of the challenges in the recognition and binding of G-quadruplexes is the competition with duplex (double-stranded) DNA. While it was reported that cationic tetra(A-methylpyridiniumyl) porphyrin, 23 Mn, could target quadruplex DNA, there was no discrimination, since it was also found to bind duplex DNA well. In 2007, Dixon et al. reported a pentacationic manganese(III)... 

Miscellaneous Metal Ions.—Mention has been made already of a relatively slow formation reaction for the normally labile manganese(ii) ion. Incorporations of the labile bivalent metal ions zinc(ii), copper(ii), manganese(n), cobalt(ii), and nickel(n) into water-soluble porphyrin molecules such as tetrakis-(4-N-methyI-pyridyl)porphine, tetrasulphonated tetraphenylporphine, and uroporphine are also relatively slow reactions. However, by taking into account the porphyrin deformation which is necessary, an Id mechanism can be fitted to these reactions. The rates of formation and dissociation of nickel(ii), copper(n), cobalt(ii), and zinc(ii) complexes of the sterically hindered ligand 1,4,8,11-tetramethyl-1,4,8,11-tetra-azacyclotetra-decane (Meicyclam) are also 10 —10 smaller than is normal for these metal ions. ... 

Sulfadimethoxine (SMD) is a dmg frequently used to prevent the spreading of diseases in freshwater fish aquaculture, but its control is important to avoid environmental contamination. A potentiometric sensor selective to SMD was built inside a micropipette tip [211] by immersing a PVC membrane loaded with 1 % of meTO-tetra(phenyl)porphyrinate manganese(lll) chloride in a reference solution. This electrode gave near Nemstian response (54.1 mV/decade) and excellent detection limit (2.4 x 10 mol L ) was attained. For the quantification of SO2, a selective electrode was prepared by incorporation of Cio-(tetraphenyl)porphyr-inate zinc(ll) in a PVC membrane plasticized with 2-nitrophenyl-phenylether [212]. The new electrode presented a selective response to sulphite, with good linearity in an interval larger than four decades of concentration and slope of -59.5 mV per decade, and detection limit of 3.7 x 10 mol L . This sensor presented high... 

Quintino MSM, Araki K, Toma HE, Angnes L (2008) New hydrazine sensors based on electropolymerized meso-tetra(4-sulphonatephenyl)porphyrinate manganese(III)/silver nanomaterial. Talanta 74(4) 730-735... 

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