Approaches towards the enantioselective recognition of anionic guest species using chiral receptors based on rhenium(I) and ruthenium(II) with amide bipyridine ligands

The syntheses of chiral anion receptors based on rhenium(i) and ruthenium(i i) with amide bipyridine ligands are reported. The rhenium(i) hosts were pr epared in moderate to high yields by co-ordinating chiral bipyridine ligand s to a Re(CO)(3)Br centre. The ruthenium(ii) receptors were synthesised via the chiral building blocks Lambda- and Delta-[Ru(bpy)(2)(py)(2)](2+) or by chromatographic resolution on a SP Sephadex C-25 cation exchanger. Chiral purity was determined by H-1 NMR and circular dichroism spectroscopy and la nthanide shift experiments. H-1 NMR titration studies showed that these rec eptors bind chiral carboxylate anions in DMSO-d(6), although significant ch iral discrimination was not observed.