Heme-protein active site models via self-assembly in water

Water solubile module of heme-protein active sites are obtained via the self-assembly of cationic porphyrins 1 and tetrasulfonato Clix[4]arene 2(K1-2=105 (m-1). Selective binding of ligands either outside or inside the cavity of assemblies 1-2 via coordination to the zinc center has been observed. Small ligands such as 4-mthylpyridine and 1-methylimidazole are encapsulated, while the bulkier caffeine is bound outside. Assemblies Co-1.2, in which the Zn porphyrin moiety has been replaced by a CoII porphyrin, ca act as O2 carriers.