Three new POM-based coordination polymers with 1,3,5-tris(1-imidazolyl)benzene ligand: syntheses, structures and proton conductivity

Abstract

Three new POM-based coordination polymers, [Cu(timb)₂(W₆O₁₉)]_n (1), {[Zn₃(Htimb)₂(H₂timb)₂(H₂O)₂(ZnW₁₂O₄₀)₂]·2H₂O}_n (2), and {[Ni(Htimb)(H₂O)₃(H₂W₁₂O₄₀)_0.5]·3H₂O}_n (3) (timb = 1,3,5-tris(1-imidazolyl)benzene), have been prepared under hydrothermal conditions. Compound 1 contains one 3D framework constructed by Cu^II atoms and timb ligands with a rare 3,6-connected pyr topology, while the polyoxoanions are situated in the cavities. For compound 2, the 3D framework is composed of a 2,4-connected network (A) and hcb network (B) in the BBABB mode. The 1D chains of compound 3 are arranged into a 3D framework by a variety of hydrogen bonding interactions between the [H₂W₁₂O₄₀]⁶⁻ polyoxoanions, coordinated water molecules and free water molecules. Magnetic data of compounds 1 and 3 show the presence of antiferromagnetic behavior. In addition, the highest proton conductivities of compounds 2 and 3 reach 2.32 × 10⁻⁵ S cm⁻¹ and 3.38 × 10⁻⁵ S cm⁻¹ at 358 K and 98% RH, respectively.