<i>meso</i>-Tetrakis(α,α,α,α-<i>o</i>-amidophenyl)porphinatoiron(II) Bearing a Proximal Histidyl Group at the β-Pyrrolic Position via an Acyl Bond: Synthesis and O<sub>2</sub>Coordination in Aqueous Media
meso-Tetrakis(α,α,α,α-o-(1-methylcyclohexanamido)phenyl)porphinatoiron(III) bearing a proximal histidyl group at the β-pyrrolic position via an acyl bond (4c) has been synthesized. Human serum albumin (HSA) incorporating the ferrous complex (4d) formed a stable O2 adduct under physiological conditions (pH 7.4, 37 °C). Although an electron-withdrawing acyl group is attached to the porphyrin periphery, the O2-binding affinity of HSA-4d was slightly higher than that of a similar analogue with a histidyl–alkylene group (2d).