An electron spin resonance study of frozen aqueous solutions containing 5,10,15,20-tetrakis(N-methyl-4′-pyridinio)porphyrinatocobait(II)

Abstract

E.s.r. spectra are reported for frozen solutions (77 K) of the 5,10,15,20-tetrakis(N-methyl-4′-pyrrdinio) porphyrinatocobalt(II) cation in pure water and water containing a variety of N donors. In pure water the (hydrated) monomer seems to be present, but with most of the N donors [including piperazine-N,N′- bis(ethane-2-sulphonic acid) buffer], N hyperfine splitting in the e.s.r. spectra shows the formation of 1:1 adducts. The reactivity of these species towards dioxygen has been investigated, and a number of dioxygen adducts characterized.