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 Zn(II) coordination polymer, catena-poly[[[[(pyridine-2,6-di-carboxyl-ato-κ(3) O,N,O')zinc(II)]-μ-1,4-bis-(1H-imidazol-1-ylmeth-yl)benzene-κ(2) N (1):N (1')] hemi{bis-[μ-1,4-bis-(1H-imidazol-1-ylmeth-yl)benzene-κ(2) N (1):N (1')]bis-[(pyridine-2,6-di-carboxyl-ato-κ(3) O,N,O')zinc(II)]}] nona-hydrate], {[Zn(C(7)H(3)NO(4))(C(14)H(14)N(4))][Zn(2)(C(7)H(3)NO(4))(2)(C(14)H(14)N(4))(2)](0.5)·9H(2)O} (n) or {[Zn(2)(2,6-PDC)(2)(bix)(2)]·9H(2)O} (n) [where 2,6-PDC = pyridine-2,6-di-carboxyl-ate, C(7)H(3)NO(4), and bix = 1,4-bis-(1H-imidazol-1-ylmeth-yl)benzene, C(14)H(14)N(4)], was synthesized and characterized. The mol-ecular structure comprises two Zn(II) units. Both Zn(II) 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 Zn(II) ions are bridged by gauche-bix ligands, providing a dinuclear [Zn(2)(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.