Synthesis, X-ray structure and alkali-metal binding properties of a new hexahomotriazacalix[3]arene

Hexahomotriazacalix [3] arene 1 has been synthesized by the reaction of 2,6-bis(chloromethyl)-4-methylphenol 6 with glycine methyl ester hydrochloride under high-dilution conditions. The crystal structure of 1 indicates that the macrocycle adopts a cone shape in the solid state with all three ester groups on the same side and within the cone of the macrocycle. In contrast with the calixarenes, macrocycle 1 exhibits only a modest degree of cupping. 1H NMR spectra indicate that the cone and partial cone isomers of 1 are rapidly interconverting in the NMR timescale at room temperature. Macrocycle 1 exhibits no significant extraction of alkali metal picrates from aqueous solution.