Synthesis and Properties of a One-Dimensional Mixed-Ligand Cd(Ⅱ) Complex with Helical Structure

The title complex, ·3H₂O_<em>n ( 1 ) (Him is imidazole, OH-H₂BDC is 5-hydroxyisophthalic acid), was synthesized by liquid/liquid diffusion method at room temperature. The complex crystallizes in orthorhombic, space group P2₁2₁2₁, with a0.671?6(7), b1.380?6(2), c1.742?1(2)?nm, V1.615?2(3)?nm³, C₁₁H₁₈CdN₂O₁₀, M_r450.67, D_c1.853?g/cm³, μ1.407?mm^-1, F(000)904, Z4, the final R₁0.020?9 and wR₂0.045?3 for 3?211 observed reflections (I>2σ(I)). In the structure of 1 , the OH-BDC ligands exhibiting bis-bidentate coordination mode bridge the adjacent Cd centers to form a one-dimensional helical chain and the second ligand Him acting as terminal ligands are attached to the helical chain. It is notable that a series of complicated hydrogen bonds (e.g., N—H…O, O—H…O) exist in the structure, which link neighboring helices into a three-dimensional supramolecular architecture. An observed intense blue luminescence with an emission band peaking at 390?nm for 1 may be resulted from ligand-to-metal charge transfer (LMCT).