2019/01/09 by Baishakhi Mondal, Soumen Saha, Dibyajyoti Borah +2 · 4 citations
Chemistry · Medicine · Materials Science · #Metal-Catalyzed Oxygenation Mechanisms #Nitric Oxide and Endothelin Effects #Porphyrin and Phthalocyanine Chemistry
paper · doi:10.1021/acs.inorgchem.8b02722
The reaction of a cobalt porphyrin complex, [(F8TPP)Co], 1 F8TPP = 5,10,15,20-tetrakis(2,6-difluorophenyl)porphyrinate dianion in dichloromethane with nitric oxide (NO) led to the nitrosyl complex, [(F8TPP)Co(NO)], 2. Spectroscopic studies and structural characterization revealed it as a bent nitrosyl of CoNO8 description. It was stable in the presence of dioxygen. However, it reacts with H2O2 in acetonitrile (or THF) solution at −40 °C (or −80 °C) to result in the corresponding Co(III)-nitrate complex, [(F8TPP)Co(NO3)], 3. The reaction presumably proceeds via the formation of a Co-peroxynitrite intermediate. X-Band electron paramagnetic resonance and electrospray ionization–mass spectroscopic studies suggest the intermediate formation of the [(porphyrin)Co(III)–O•] radical, which in turn supports the generation of the corresponding Co(IV)-oxo species during the reaction. This is in accord with the homolytic cleavage of the O–O bond in heme-peroxynitrite proposed in the nitric oxide dioxygenases activity. In addition, the characteristic peroxynitrite-induced phenol ring reaction was also observed.