| Abstract
| - The heteroditopic receptors 1 and 2 firmly include an AgI ion into the NS2O2 crown and establish selective H-bondinteractions with anions at the covalently linked urea/thiourea (U/T) subunit. Studies in MeCN solution showed thatthe metal center induces a 103−106-fold enhancement of the anion association constant, due to a coordinativeinteraction with the O/S atom of the U/T moiety. In the presence of F-, the Ag−O interaction promotes the releaseof a proton from one of the urea N−H fragments. AgI coordination to the S atom of the thiourea derivative 2promotes the formation of unusually stable H-bond complexes with Cl- and Br-.
- Intramolecular coordination to the AgI center, encircled by a macrocycle, drastically enhances the H-bond donor tendencies of covalently linked urea and thiourea units toward oxoanions and halide ions. In the presence of fluoride, metal coordination promotes the deprotonation of one N−H group of the urea fragment.
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