Halide Recognition by Tetraoxacalix[2]arene[2]triazine Receptors: Concurrent Noncovalent Halide–π and Lone‐pair–π Interactions in Host–Halide–Water Ternary Complexes

Abstract

Cleft of center: The self fine-tuning π-deficient cleft of 1,3-dichloro-substituted tetraoxacalix[2]arene[2]triazine forms noncovalent π–halide and π–lone-pair-electron interactions with halides Cl− and Br−, and water, giving rise to ternary complexes in the solid state (see structure, N blue). In solution, the host molecule, formed by a different mechanism, complexes with fluoride, giving Ka (1:1) of over 4000 M−1.