Self-assembled metallo-macrocycle based coordination polymers with unsymmetrical amide ligands

Abstract

A series of metallo-macrocyclic based coordination polymers has been prepared from flexible amide ligands N-6-[(3-pyridylmethylamino)carbonyl]-pyridine-2-carboxylic acid (L1-CH₃) and N-6-[(4-pyridylmethylamino)carbonyl]-pyridine-2-carboxylic acid (L2-CH₃). In all but one case, self-assembled dinuclear metallo-macrocyclic units form the basis of the polymeric structures, whereby discrete metal centres, and dinuclear or trinuclear clusters, are linked by the self-assembled macrocycles to give 1D and 2D coordination polymers. In one instance, a 1D coordination polymer is formed in a reaction carried out under ambient conditions; when the same reaction is conducted under solvothermal conditions a 2D structure is formed. In all but two of these structures, the polymeric chains and nets are close-packed within the crystals. In the case of a 6,3-connected 2D coordination polymer {[Cd₃(L2-CH₃)₃(NO₃)(L2)(CH₃OH)](NO₃)₂·12½H₂O}_n (9), small oval channels percolate down the a-axis of the unit cell.