A novel coordination polymer [Cd(L)(H₂O)₃]•2H₂O (H₂L＝4'-hydroxy-7-carboxy-methoxyisofla- vone-3-sulfonate) was synthesized and characterized by means of single-crystal X-ray diffraction (XRD) analysis, elemental analysis, IR analysis, etc. The crystal structure belongs to monoclinic system, space group P2₁/a, with a＝1.3691(3) nm, b＝0.72157(16) nm, c＝2.0163(5) nm, α＝90°, β＝93.501(4)°, γ＝90°, V＝1.9882(8) nm³, M_r＝592.79, Z＝4, D_c＝1.980 g•cm^－3, F(000)＝1192, μ＝1.283 mm^－1, R₁＝0.0387, wR₂＝0.1224. The results showed that Cd atom is six-coordinated by two oxygen atoms from different sulfonate groups [O(8), O(7B)], one oxygen atom from carboxylate group of another ligand [O(5A)], and three oxygen atoms from the coordinated water molecules [O(11), O(12)] in a distorted octahedron geometry. The compound was a 2D layered coordination polymer with double helical chains. In the compound, there are left-handed Cd-L chains and right-handed Cd-L chains, and these two kinds of chains connected by O(7) from a sulfonate group are interlaced. There are abundant and complex hydrogen bonds among coordinated water, lattice water, CO₂, SO₃, O, CO and OH in the crystal. The layers are connected via complex hydrogen bonds into a 3D supramolecular framework.

Key words: double helical chain, crystal structure, hydrogen bond, daidzein, coordination polymer