Abstract: Disclosed is a metalloporphyrin-ligand complex which includes (a) a meso-tetraphenylporphyrin, (b) a crown ether rigidly attached to the meso-tetraphenylporphyrin by covalent attachment on one side of the porphyrin to two diagonally opposing phenyl groups, (c) a metal bound to the pyrrole nitrogens of the porphyrin, (d) a bridge covalently linking two diagonally opposing phenyl groups on the other side of the porphyrin, effective to hinder .mu.-oxo diner formation, and (e) a ligand having (i) a primary amine which is held noncovalently by the crown ether and (ii) a metal-coordinating atom which is coordinately bound to the metal.In another aspect, the invention includes a water-soluble oxygen carrier. The oxygen carrier includes a meso-.alpha.,.alpha.,.alpha.,.alpha.-tetrakis(o-propanoylamino)phenylporph yrin, in which the 3-carbons of the propanoyl groups are each covalently bound to a quaternary amine, and iron or cobalt is bound to the pyrrole nitrogens of the porphyrin.