Synthesis,Crystal Structure and I_2 Capture of a Cd(Ⅱ) Coordination Polymer Based on a Linear Bipyridyl Benzene Ligand

A new complex with formula [Cd(3-pbpmb)_2 I_2]_n 1(3-pbpmb = 1,4-bis(pyridine-3-ylmethoxy)benzene), has been solvothermally synthesized and characterized. The crystal belongs to monoclinic system, space group P21/n with a = 8.2905(17), b = 16.078(3), c = 13.213(3) ?, β = 99.44(3)°, Mr = 950.86, V = 1737.3(6) ?~3, Z = 2, Dc = 1.818 g/cm~3, F(000) = 924, m = 2.450 mm~(-1), the final R = 0.0198 and w R = 0.0467 for 3053 observed reflections(I 2σ(I)). The Cd(Ⅱ) ion is coordinated by four N atoms of four 3-pbpmb ligands and two iodine ions to furnish a distorted octahedral coordination geometry. The Cd(Ⅱ) ion and its own symmetry-related ions are bridged by N atoms from two 3-pbpmb ligands to generate a zigzag 1-D chain coordination polymer. These 1D chains are further connected into a three-dimensional(3D) framework by C–H×××pinteractions and intermolecular C–H×××I hydrogen bond. Interestingly, 1 displays efficient sorption of molecular iodine gas(up to 111 wt%), but invalid sorption of molecular water gas.