A convenient method for measuring pervaporation through monolayers at the gas-water interface

Perforated monolayers. Progress report, July 1, 1990--December 31, 1992

“…Introduction of bulky p-tert..butyl groups onto the upper rim of the caiix[6]arene framework significantly reduces intermolecular polyether interactions. Qualitatively, similar behavior has been found with analogous calix [4]arene-based octopi. In principle, the ability to control the orientation of such tentacles should allow one to fine-tune the octopus's interaction with a guest ion or molecule.…”

“…It could, therefore, provide the basis for novel means of separating ions and/or molecules. c) Pinched Cone Conformers of Calix [4]arene. The cone conformational isomer of 5,11,17,23-tetracarboxy-25,26,27,28-tetra-n-octylcalix[4]arene (2) and 5,11,17,23tetracarboxamido-25,26,27,28-tetra-n-octylcalix[4]arene (3) have been synthesized and found to exist as equilibrating C2v structures.…”

“…These findings represent the f'trst experimental evidence for the existence of C2v conformational isomers of a calix! [4]arene in solution. The free energy of activation for the interconversion, calculated from the temperature at which the aromatic protons coalesce from _wo singlets to one, was 14.1 kcal tool "1for 2 at 45°C, and 13.3 kcal tool-1 for 3 at-4°C.…”

“…Calix [4]arenes. Alkylation of 25,26,27, 28-tetrahydroxycalix[4]arene with 1-bromooctane afforded the corresponding tetra-n-octyloxyether, which was readily isolated as the cone isomer.…”

“…Friedel-Crafts acylation (CH3COC1) of this tetraether afforded 5,11,17,23-tetraacetyl-25,26,27,28-tetrakis-(1-n-octyloxy)calix [4]arene (4); subsequent haloform oxidation, and esterification (CH2N2), yielded 5,11,17,23-tetracarboxymethyl-25,26,27,28-tetrakis-(1-noctyloxy)calix [4]arene (5). 5,11,17,26,27,arene (6) was prepared by bromination of the starting tetra-n-octyloxyether (NBS), followed by sequential displacement with cyanide and hydrolysis.…”