Structural stabilities of sulfonated manganese tetramesitylporphyrin and its β-brominated analogue toward NaOCl, H2O2 and (CH3)3COOH

This article gives the degradation rate constants of meso-tetrakis(3,5-disulfonatomesityl)porphinatomanganese(III) X (where X=H₂O and/or OH^? depending on pH) (MnTMSP) and its β-brominated analogue (MnTMSPBr₈) toward the oxidants NaOCl, H₂O₂, and (CH₃)₃COOH at various pHs, I=0.2 M and 30°C. In addition, the degradation rate constants of MnTMSP was determined when it was bound to cationic supports — namely, CTAB, a poly(vinylbenzyltrimethylammonium chloride) latex, 2,6-ionene and 2,10-ionene. MnTMSP showed high structural stability toward the peroxides in strong acidic medium and the degradation rate constants were found as low as 10^?4 min^?1 at pH<1.50. When NaOCl was employed as the oxidant, the pH dependence of the stability of MnTMSP was vice versa and its degradation rate constant was determined as 1.43×10^?4 min^?1 at pH 14.10. In strong acidic solution, the supports CTAB and latex made the stability of MnTMSP toward the peroxides improve significantly. In strong basic solution, only latex-bound MnTMSP showed higher stability toward NaOCl than the homogeneous MnTMSP. Because MnTMSPBr₈ was not stable in solutions having pH higher than 9 and containing no oxidant, its stability was investigated at pH<9 and it showed slightly lower stability toward the peroxides than the non-brominated analogue.