Synthesis of a complementary dimer from mono(imidazolyl)-substituted cobalt(II) porphyrin as a new artificial T-form hemoglobin

Mono(imidazolyl)-substituted Co(II) porphyrin dimer with a ‘picket fence’ structure was synthesized as a new artificial hemoglobin model containing two binding sites. The dimer was confirmed by UV–vis, resonance Raman and ESR spectral measurements to bind two dioxygen molecules reversibly. The dioxygen binding affinity of the dimer was lower than that of the corresponding monomer. The decrease in this affinity is discussed in terms of steric hindrance and orientational effect of the axial ligand.