HemoCD as a Totally Synthetic Artificial Oxygen Carrier: Improvements in the Synthesis and O /CO Discrimination.

HemoCD, which is composed of an iron(II)porphyrin such as 5,10,15,20-tetrakis(4-sulfonatophenyl)porphinatoiron(II) (Fe(II)TPPS) and a cyclodextrin (CD) dimer having a pyridine linker, represents a synthetic hemoglobin (Hb) model compound that exhibits reversible oxygen (O ) binding ability in aqueous solution at an ambient temperature. Therefore, hemoCD has the potential to be used as a totally synthetic artificial oxygen carrier. In this article, we describe the improvements of hemoCD related to its synthesis and O /CO selectivity. The synthesis procedure of the CD dimer of hemoCD was re-examined, and the CD dimer was successively synthesized from inexpensive β-CD with a 38% yield (three-steps), which enabled us to obtain the CD dimer in gram-quantities. The O /CO selectivity of hemoCD was also markedly improved using an iron(II)porphyrin having a carboxylate group at the distal site of hemoCD.