A calixarene-porphyrin duplex was prepared by mixing equimolar amounts of hydroxy or carboxy calixarene derivatives and pyridyl or o-aminophenylporphyrin derivatives. Electrospray ionization mass spectrometry (ESI-MS) was applied to screen a suitable pair of a calixarene and a porphyrin. meso-Tetra(2-pyridyl)porphyrin formed a duplex with tetrahydroxy or tetrahydroxymethylcalixarene via triple or quadruple hydrogen bonds. 1H NMR spectra showed that the tetrahydroxycalixarene was symmetrically located upon the porphyrin ring, whereas trihydroxycalixarene was slanted on the porphyrin ring. The duplex of meso-tetra(2-pyridyl) porphyrinatocobalt(II) and tetrahydroxymethylcalixarene formed a complex with benzylimidazole, which was capable of reversible dioxygen-binding. The capping structure upon porphyrin provided by calixarene raised the life-time of dioxygen-adduct compared with the porphyrin without calixarene.
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