Structural Studies of Water-Soluble \beta-Brominated Manganese Porphyrins: Stabilities of MnTDCSPPBr _{8} and MnTSPPBr _{8} as Homogeneous and Supported Reagents Toward Hydrogen Peroxide and Sodium Hypochlorite


Abstract: This article describes the structural stabilities of [2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphinato]manganese(III) X (where X = H_{2}O and/or OH^{-} , depending on pH) (MnTDCSPPBr_{8} ) and [2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetra(4-sulfonatophenyl)porphinato] manganese(III) X (where X = H_{2}O and/or OH^{-} , depending on pH) (MnTSPPBr_{8} ) toward H_{2}O_{2} and NaOCl at various pH's, I = 0.2 M and 30^oC. In addition, the structural stabilities of these manganese porphyrins were investigated when they were bound to quaternary ammonium containing supports, namely, hexadecyltrimethylammonium bromide (CTAB), 2,6-ionene, 2,10-ionene and a poly[(vinylbenzyl)trimethylammonium chloride] latex. In alkaline media, both manganese porphyrins degraded and precipitated even in the absence of both of the oxidants. In neutral and acidic solutions, they showed increasing stabilities toward H_{2}O_{2} as pH decreased and almost no stabilities toward NaOCl. When bound to CTAB and the latex, they gained very high stabilities toward H_{2}O_2 at pH < 2 and almost no degradation was observed. On the other hand, the stabilities of the ionene-bound manganese porphyrins were close to the free complexes. The pseudo-first order degradation rate constants of MnTDCSPPBr_{8} , MnTSPPBr_{8} and their supported analogues were determined.


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