31-Benzyloxy-5,11,17,23,29-penta-tert-butylcalix[5]arene-32,33,34,35-tetraol

Abstract

The title compound, C62H76O5, known to be one of the most versatile synthetic precursors/inter­mediates of calix[5]arene derivatives, adopts an approximate C s-symmetric cone-in conformation. The aryl­oxybenzyl ring is tilted in such a way that the p-tert-butyl group fills the macrocycle cavity, while the benzyl group moves away from the cavity axis. In the crystal, this conformational arrangement is secured by intra- and inter­molecular O—H⋯O hydrogen bonds forming inversion dimers. Four tert-butyl groups are disordered over two orientations, with occupancy ratios of 0.745 (6):0.255 (6), 0.837 (5):0.163 (5), 0.850 (5):0.150 (5) and 0.845 (8):0.155 (8).

The sulfonate group as a ligand: a fine balance between hydrogen bonding and metal ion coordination in uranyl ion complexes

“…contains two crystallographically independent complex molecules, and 9 only one, the U-O(sulfonate) bond lengths being 2.332 4 Examination of calixarene structures reported in the CSD shows that such hydrogen bonding between phenolic/ate groups of facing molecules is not particularly frequent, but some examples are found, as with calix [5]arene derivatives, 62,63 in which, as in the present case, the intermolecular hydrogen bonds seem to be stronger than the intramolecular ones. 62 As a result of this arrangement, complex 8 displays "up-down" orientation of the calixarene units as in "clay-like" derivatives, 5 with double sheets of hydrogen bonded calixarenes parallel to (001) separated by layers of phosphonium cations (with other cations located within the double layers).…”