Capped Biscalix[4]arene-Zn-Porphyrin: Metalloreceptor with a Rigid Cavity

摘要

Sterically hindered (e.g. strapped, capped, picket-fence, basket-handle, etc.) porphyrins are widely known as chemical models of metalloporphyrin-dependent proteins. Oxygen and carbon monoxide transport and storage by superstructured metalloporphyrinsand mimicking of cytochrome P-450 and cytochrome C oxidase activity as well as electron transfer processes have been performed. Metalloporphyrins are also being used in supramolecular chemistry for recognition and catalysis. The complexation ability ofZn--tetraarylporphyrins toward a wide variety of polar organic molecules and anions has been extensively studied. Immobilization of different binding sites (crown ethers, Kemp's triacid derivatives, xanthene skeleton, diamidopyridines, etc.) on the (metallo)porphyrin platform gives rise to specific size-shape selectivity in substrate recognition. Recently Bonar-Law and Sanders reported large receptors in which a Zn--porphyrin core was included into a large three-dimensional array of one or two cholic acid modules, bearing convergent hydroxyl groups, which showed strong binding of polyols, pyridines, imidazole, purine, etc. Cyclodextrin-capped porphyrins have been reported to exhibit pronounced P-450 like activity and photoin-duced electron transfer toward quinones.