Novel Zn and Cd coordination polymers of 1,1′-(1,6-hexanediyl)bis-1H-benzimidazole: solvothermal synthesis, crystal structures and photoluminescence properties

Solvothermal reactions of 1,1'-(1,6-hexanediyl)bis-1H-benzimidazole (hbbm) with Zn(II), or Cd(II) salts yielded six coordination polymers, [MX2(hbbm)](n) (1: M = Zn, X = Cl; 2: M = Zn, X = Br), {[CdI2(hbbm)]center dot 0.5H(2)O} n (3), [CdCl2(hbbm)(2)](n) (4), [Cd-3(eta,mu-OAc)(2)(mu-OAc)(2)(OAc)(2)(hbbm)(2)](n) (5), and [Zn-2(mu-OAc)(4)(hbbm)](n) (6). Compounds 1-6 were characterized by elemental analysis, IR, powder X-ray diffraction, and single crystal X-ray diffraction. Compounds 1-3 contain a 1D zigzag chain in which [MX2] units are linked by hbbm bridges. For 4, each [Cd4Cl8(hbbm)(4)] unit acting as a planar four-connecting node connects other four equivalent ones via eight hbbm molecules to form a 2D (4,4) network. For 5, each linear [Cd-3(eta,mu-OAc)(2)(mu-OAc)(2)(OAc)(2)] unit is linked by two pairs of hbbm bridges to afford a 1D double chain. For 6, each [Zn-2(mu-OAc)(4)] unit is connected by hbbm bridges to form a 1D U-type chain, which further interweaves with other adjacent chains to form a unique 3D net. The solid state luminescent properties of 1-6 at ambient temperature were also investigated.