Construction of Four γ-Octamolybdate-Based Coordination Polymers Using Linear Nitrogen Heterocyclic Ligands for Proton Conduction

Abstract

POM-based coordination polymers are emerging as promising crystalline materials for proton conduction. Herein, we successfully synthesized four new γ-octamolybdate-based coordination polymers using the linear nitrogen heterocyclic ligand 1-(4H-1,2,4-triazole-4-yl)-4-(imidazole-1-yl) (benzene [tib]), which are designated as {[Co(Htib) Due to the diverse connection modes of γ-octamolybdate and tib ligand to metal ions, the dimensionalities of their structures vary from 1D and 2D to 3D. Compound 1 exhibits a 1D chain structure, with γ-{Mo 8 O 26 } sandwiched between Co(tib) 2 units, while compound 2 develops into a 2D layered structure through the linkage of {Zn 2 Mo 8 O 26 } units with μ 2 -tib ligands. Compounds 3 and 4 display 3D structures, where the former is constructed from 1D {Mo 8 O 26 } n chains and Ni 2 (tib) 2 units and the latter is formed by linking tib ligands to adjacent 2D layers, which are composed of the distinctive {Mo 8 O 28 } units and Cu II ions. Moreover, abundant hydrogen bonds are present in four compounds, which is beneficial for proton transport. The proton conductivity values of compounds 1