Efficient enantiorecognition of ruthenium(II) complexes by silica-bound teicoplanin

A series of chiral tris-diimine ruthenium(II) complexes have been resolved by HPLC on a chiral stationary phase. The stationary phase (CSP1) was prepared by covalent attachment of the glycopeptide antibiotic teicoplanin to isocyanate activated silica gel. CSP1 selectively retains the enantiomers of [Ru(L)(3)](2+) (L = 2,2'-bypyridine (bpy), 1,10-phenanthroline and 4,7-diphenyl-1,10-phenanthroline), with a preference for the Delta isomer. For the mixed-ligand complexes [Ru(bpy)(2)pztr](+) and [Ru(bpy)(2)pytr](+) (Hpztr = 3-(pyrazin-2-yl)-1,2,4-triazole, Hpytr = 3-(pyridin-2-yl)-1,2,4-triazole), where the triazole unit is bound to the metal centre either through the N-2 or the N-4 nitrogen of the ring, CSP1 discriminates both the enantiomers and the regioisomers. Diastereo- and enantioselective association was also observed between CSP1 and the stereoisomers of the dinuclear complex ((Ru(bpy)(2))(2)bpt](3+) (Hbpt = 3,5-bis(pyridin-2-yl)-1,2,4-triazole), with differences in binding affinities of 1.4 kJ/mol between the homochiral enantiomers. (C) 2000 Elsevier Science Ltd. All rights reserved.