Syntheses and ion selectivities of tri-amide derivatives of hexahomotrioxacalix[3]arene. Remarkably large metal template effect on the ratio of cone vs. Partial-cone conformers

• Published in: Tetrahedron 1995-04, Vol.51 (16), p.4647-4654
• Main Authors: Matsumoto, Hitoshi, Nishio, Shoko, Takeshita, Michinori, Shinkai, Seiji
• Format: Article
• Language: English
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/0040-4020(95)00165-5

We have found that a homotrioxacalix[3]arene (1H 3) -based ionophore with a cone conformation, which is very difficult to obtain by the reaction of 1H 3 and ethyl bromoacetate, can be synthesized quantitatively by the reaction of 1H 3 and N, N-diethylchloroacetamide in THF in the presence of NaH. The conformer distribution of the tri-amide derivative (1Am 3) between cone and partial-cone was sensitively affected in 0 ∼ 100% range by the metal template effects. Cone-1Am 3 showed the very high affinity for alkali and alkaline earth metal cations. Particularly, it formed stable complexes with alkaline earth metal cations which were scarcely bound to the tri-ester derivative. The results show that cone-1Am 3 acts as an excellent neutral ionophore owing to the three coordinative amide groups arranged in C 3-symmetry. The conformer distribution of the tri-amide dirivatives of hexahomotrioxacalix[3]arene between cone and partial-cone was sensitively affected in 0 ∼ 100% range by the metal template effects.