Synthesis of Substituted μ-Oxo-bis[tetra-phenyl porphyrinatoiron] Compounds from Free Base Porphyrins by a One-pot Method*

A novel method for synthesis of substituted μ-oxo-bis[tetraphenyl porphyrinatoiron] compounds ([TRPPFe]2O) based on the reaction among free base porphyrins (TRPPH2), FeSO4·7H2O and H2O in one pot was proposed and investigated. Four kinds of [TRPPFe]2O were synthesized by this novel synthetic method, and their structures were characterized by elemental analysis, infrared spectra and UV-vis spectroscopy. The reaction conditions, including the effect of different iron salts on the formation of [TRPPFe]2O, the reaction time between FeSO4·7H2O and TRPPH2, the molar ratio of FeSO4·7H2O/TRPPH2 as well as the volume ratio of H2O/DMF, were investigated. The [TRPPFe]2O yield of 93%-98% could be obtained under the following optimal conditions: the reaction time of FeSO4·7H2O with TRPPH2 was about 10 h, the molar ratio of FeSO4·7H2O/TRPPH2 about 5:1, and the volume ratio of H2O/DMF exceeded 2:1. Further research indicated that only TRPPFeCl were formed once FeSO4·7H2O was replaced by FeCl2·4H2O, the reason of which might be that halogen ions in iron salts interfered the formation of [TRPPFe]2O, suggesting that halogen ions should be avoided in this novel synthetic method.