A Rare 2D Framework Cu(atz)₂ with Ferrimagnetic and High Proton Conductivity

Materials combining proton conductivity and magnetism have attracted great attention in recent years due to their intriguing application in sensors and fuel cells. Herein a two-dimensional metal-organic framework, [Cu(atz)₂ (H₂ O)₂ ]⋅H₂ O (1) (Hatz=5-aminotetrazole), has been obtained in a green synthesis method. The single-crystal structure revealed that the atz^- ligands as linkers coordinate with copper ions to sql networks, between which water molecules are immobilized through hydrogen bonds. The resulting complex 1 exhibits a high proton conductivity of 1.11×10^-4 and 6.19×10^-4  S cm^-1 at room temperature and 333 K, respectively, under 98% RH with an activation energy of 0.56 eV. Upon dehydration, the proton conductivity of 1_dg drops by an order of magnitude. Furthermore, the magnetic behavior changes from long-range ferrimagnetic ordering of 1 to canted antiferromagnetic behaviour of 1_dg.