Cryptands revisited - Design, synthesis, complexation behaviour and structural analysis of borocryptands

A new family of abiotic receptor molecules of the cryptand type (borocrypta nds) was designed by combining structural features of naturally occurring a ntibiotics such as boromycin and aplasmomycin and cryptands. Their binding ability towards alkaline metal cations was established both in solution and in the solid state. The binding ability of borocryptands was further expan ded to the molecular recognition of NH4+ cationic molecule. Finally, enanti omeric differentiation of chiral borocryptates using NMR spectroscopy in a liquid crystalline medium was achieved. The chirality at the substrate, obs erved for the first time, was described as being induced by the structure o f the receptor and mediated by the peristatic chirality of the cavity to th e complexed substrate. (C) 1998 Elsevier Science S.A. All rights reserved.