Extended structures built on a triphenoxymethane platform - C-3-symmetric,conformational mimics of calix[n]arenes

A series of C-3-symmetric tris(3,S-dialkyl-2-hydroxyphenyl)-methanes (alkyl = tert-butyl, methyl, tert-pentyl) have been synthesized in high yield fro m their respective phenols and fully characterized, including single crysta l X-ray structures for two examples. The di- teri-butyl-substituted compoun d, la, has been derivatized to a tris-acid chloride, 4, which was treated w ith a variety of amines (dimethylamine, benzylamine, glycine, and alanine) from which the corresponding tris-amides 5-8 were formed. The absolute geom etry and conformation of the dimethylamine, glycine, and alanine derived sy stems were determined by X-ray analyses, and in all cases, the three phenol ate arms point up with respect to the central methine. Alkali metal binding studies (Li, Na, K, Rb, and Cs) were carried out for the dimethylamine, be nzylamine, and glycine compounds 5-7, and these compounds were found to hav e some selectivity for potassium cations, NMR studies demonstrate that C-3 symmetry is retained in all the compounds and the stoichiometry for lithium ion complexation is 1:1, whereas two ligands are needed to complex sodium cations. Crystal structures of the dimethylamine derivative with lithium pi crate and the benzylamine and glycine derivatives with sodium tetraphenylbo rate were also determined.