Stereoelectronic effects of the meso-substituents on the catalytic performance of iron(III) meso-tetraarylporphyrins: Pyridyl and N-methylated pyridyl groups compared to phenyl, 4-methoxyphenyl and 4-sulfonatophenyl ones

Porphyrins functionalized by quaternary pyridinium units

“…One should take note of the increasing number of reports concerning porphyrins functionalized by pyridinium units for their useful applications in biological studies [116][117][118][119], as well as for showing other valuable properties [120][121][122].…”

Manganese porphyrins/mesoporous amberlyst 15 nanocomposites: Robust biomimetic catalysts for aqueous oxidation of olefins

“…[13,15] As we have shown previously, there is a much better correlation between the catalytic activity of iron meso-tetra (aryl)porphyrins and the electron-deficient character of the aryl substituents, in comparison with the corresponding manganese porphyrins. [15,16] Apparently, in the case of manganese porphyrins, oxygen transfer from the active oxidants, that is, six coordinate periodato or high valent oxo manganese porphyrin species, is not the rate determining step of the oxidation reaction. In other words, since the electrophilic strength of the oxygen atom involved in the oxidation reaction increases by increasing the electron-deficiency of manganese porphyrins, electron deficient manganese porphyrins are expected to be more efficient than the electron-rich complexes.…”

“…Meso-tetra(2-, 3-, or 4-pyridyl)porphyrins, the Nmethylated porphyrins, and manganese porphyrins were prepared according to the Adler method. [22,23] (See previous works [15,16,24,25] for more details including the synthesis procedure and spectral data. )…”

“…In spite of general agreement on the higher catalytic activity of the metal complexes of electrondeficient porphyrins compared to that of the electron-rich ones in the catalysis of the oxidation of organic compounds with different terminal oxidants, several studies are in favor of higher catalytic activity of the latter. [5,7,[13][14][15][16][17][18] Furthermore, the known substituent constants of different substituents determined by their effect on the acidity of benzoic acid derivatives, hydrolysis of esters or nucleophilic and electrophilic substitution reactions of organic compounds cannot simply be applied to large macroheterocycles such as porphyrins; ab initio studies on meso-tetra (aryl)porphyrins with -OCH 3 and -SCH 3 para-substituents showed greater electron donating ability of the latter, which in contrast to the order of the electron donor strength of these groups to benzene ring. [19] The influence of peripheral substituents on the catalytic activity of manganese porphyrins for oxidative organic transformations was investigated by different authors.…”

Exploring manganese pyridylporphyrin isomers for cyclohexane oxidation: First‐generation catalysts are better than third‐generation ones

“…[19,[23][24][25] Among the several classes of synthetic metalloporphyrins, the meso-tetrakis(2-, 3-or 4-pyridyl)porphyrin isomers ([MTXPyP], X = 2, 3, or 4; M = metal ion) are widely studied as biomimetic models for catalase, [26] superoxide dismutase (SOD), [27,28] and cytochrome P450 enzymes. [23,[29][30][31][32][33][34][35] Despite the versatility of the pyridylporphyrin isomers in catalyzing the oxidation of several organic substrates in a heterogeneous and homogeneous medium, [29][30][31][32][33][34] the oxidation of alkanes by these compounds has not been extensively explored.…”