Chirality in coordination polymers: homo- vs. hetero-chiral strand construction

Abstract

The functionalised cage amine complex, [1,8-bis(carboxymethylamino)sarcophagine]cobalt(III) (sarcophagine = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane), serves as a chiral supramolecular synthon in the formation of coordination polymers in which various metal(II) ions form labile links in the polymer strands. Both amorphous and crystalline polymers form, depending, amongst other factors, upon the stereochemistry at Co(III) and the nature of the metal(II) species. In the cases of Co, Ni, Cu and Zn as the linker species, polymers of 1 ∶ 1 Co ∶ M stoichiometry are obtained, whereas Mn is found to give both Co/Mn and Co/Mn₂ ‘monomer’ units. Crystal structure determinations are reported for the Co/Mn, Co/Mn₂, Co/Co and Co/Zn systems.