Unusual one-dimensional branched-chain structures assembled by a novel imidazole-containing tripodal ligand with cadmium(II) salts and their fluorescent property

Three novel coordination polymers [Cd3(L)2(μ-Br)(μ-Cl)Br3Cl] (1), [Cd3(L)2(μ-Cl)2Cl4] (2) and [Cd(L)Cl]2[CdCl4]·H2O (3) were obtained by reactions of an imidazole-containing tripodal ligand N1-(2-aminoethyl)-N1-(2-imidazolethyl)-ethane-1,2-diamine (L) with Cd(II) salts. Their structures were determined by X-ray crystallography. Crystal data for 1, monoclinic system, P21/c, a=7.752(4)Å, b=31.70(2)Å, c=14.012(7)Å, β=109.439(7)°, V=3247(3)Å3, Z=4. 2, monoclinic system, P21/c, a=7.6564(15)Å, b=31.433(6)Å, c=13.925(3)Å, β=109.89(3)°, V=3151.1(11)Å3, Z=4. 3, orthorhombic system, Pbcn, a=22.950(2)Å, b=8.435(7)Å, c=17.360(2)Å, V=3360.3(51)Å3, Z=4. Complexes 1 and 2 have similar one-dimensional (1D) branched-chain structure while complex 3 features a 1D zigzag cationic chain with [CdCl4]2− serving as counter anion. The photoluminescent measurements reveal that all the complexes exhibit blue fluorescence at room temperature in the solid state.