COMBINING THIACYCLOPHANE AND BENZOCROWN ETHER BINDING-SITES IN THE DESIGN OF HAPTOSELECTIVE LIGANDS AND METALLORECEPTORS

Bis crown ether molecules containing separate S and O donor sets are s ynthesized in two steps from commercially available benzocrown ethers. Double bromomethylation of the aromatic ring followed by S-C bond for mation in a Cs+ mediated cyclization reaction produces ditopic macrocy cles containing crown thioether and crown ether binding sites separate d by a common benzene ring. These potential ligands display haptoselec tivity, simultaneously coordinating a transition metal ion (Cu+) throu gh S-donors and an alkali metal ion (Na+, K+) in the O-donor set.. X-r ay crystallographic and NMR data verify the nature of the cation bindi ng selectivity. The resulting complexes demonstrate the potential to b ind a substrate molecule (AMP(-)) between the two metal centres (Cu+ a nd Na+). (C) 1998 Elsevier Science Ltd. An rights reserved.