Synthesis and Properties of Asymmetrically Substituted Mn(III)-Nitro-Phenylporphyrins

Abstract

Mn(III)-5-(4-nitrophenyl)-10,15,20-triphenylporphyrin and Mn(III)-5,10,15-tri(4-nitrophenyl)-20-phenylporphyrin were synthesized by complex formation reactions of the specified porphyrins and by metal exchange of Cd porphyrin complexes with MnCl₂ in dimethylformamide. The products were identified by mass spectrometry and UV-Vis, IR, and ¹H NMR spectroscopy. Partial reduction of Mn(III) to Mn(II) takes place upon dissolution of manganese(III) complexes in DMF. The addition of solid NaOH to a solution in DMF or ethanolamine gives unstable Mn(II) porphyrins. The photochemical stability and oxidative degradation of Mn(III) porphyrins were studied in chloroform and in a chloroform–hydrogen peroxide mixture. The metal exchange reaction between asymmetrically substituted Cd(II) porphyrins and MnCl₂ in DMF was studied. The kinetic parameters of the reaction were calculated. The influence of substituents and the nature of the salt on the kinetic parameters of the metal exchange reaction was identified.