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The tetraphenyl ketone of p-tert-butyldihomooxacalix [4]arene (2) was synthesized for the first time. This derivative possesses the cone conformation in solution at room temperature, which was confirmed by NMR measurements ( 1 H, 13C and NOE 1D). Extraction studies with metal picrates from neutral aqueous solution into dichloromethane, transport experiments with metal picrates through a dichloromethane membrane and stability constant measurements by UV absorption spectroscopy in methanol and acetonitrile were performed to evaluate the binding ability of ketone 2 towards alkali and alkaline earth metal cations. The tetraphenylketone of p-tertbutylcalix[4]arene (3) was also studied, and the results for the two derivatives were compared. Compound 2 shows a preference for K and Ba 2 cations, being selective only in the alkaline earth metal cation series. Compound 3 is a stronger binder than 2, but is a weaker extractant. Both show transport rates that are not proportional to complex stability or to extraction efficiency. Ketone 2 can be characterized as a selective receptor.

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