Crystal structure and characterization of a new chain-like polyrotaxane zinc(II) coordination polymer with mixed pyridine-2,6-di-carboxyl-ate and 1,4-bis-(1H-imidazol-1-ylmeth-yl)benzene ligands.

A new chain-like polyrotaxane ZnII coordination polymer, catena-poly[[[[(pyridine-2,6-di-carboxyl-ato-κ3 O,N,O')zinc(II)]-μ-1,4-bis-(1H-imidazol-1-ylmeth-yl)benzene-κ2 N 1:N 1'] hemi{bis-[μ-1,4-bis-(1H-imidazol-1-ylmeth-yl)benzene-κ2 N 1:N 1']bis-[(pyridine-2,6-di-carboxyl-ato-κ3 O,N,O')zinc(II)]}] nona-hydrate], {[Zn(C7H3NO4)(C14H14N4)][Zn2(C7H3NO4)2(C14H14N4)2]0.5·9H2O} n or {[Zn2(2,6-PDC)2(bix)2]·9H2O} n [where 2,6-PDC = pyridine-2,6-di-carboxyl-ate, C7H3NO4, and bix = 1,4-bis-(1H-imidazol-1-ylmeth-yl)benzene, C14H14N4], was synthesized and characterized. The mol-ecular structure comprises two ZnII units. Both ZnII ions are fivefold coordinated, with the coordination sphere inter-mediate between trigonal-bipyramidal and square-pyramidal, as defined by two bix ligands and one 2,6-PDC tridentate chelating ligand. For one of the units, two ZnII ions are bridged by gauche-bix ligands, providing a dinuclear [Zn2(2,6-PDC)2(bix)2] macrocycle. The other unit is built by trans-bix bridging ligands, leading to a zigzag chain-like structure. Inter-estingly, these two entities are inter-weaved, leading to a polyrotaxane structure extending parallel to [101]. The crystal structure is consolidated by hydrogen-bonding, π-π and C-H⋯π inter-molecular inter-actions.