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 Δ isomer. For the mixed-ligand complexes [Ru(bpy)₂pztr]⁺ and [Ru(bpy)₂pytr]⁺ (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 N² or the N⁴ 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)₂bpt]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. Copyright (C) 2000 Elsevier Science Ltd.