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

Abstract

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)]·0.5H₂O}_n (3), [CdCl₂(hbbm)₂]_n (4), [Cd₃(η,μ-OAc)₂(μ-OAc)₂(OAc)₂(hbbm)₂]_n (5), and [Zn₂(μ-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 [Cd₃(η,μ-OAc)₂(μ-OAc)₂(OAc)₂] unit is linked by two pairs of hbbm bridges to afford a 1D double chain. For 6, each [Zn₂(μ-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.