Proton-Conducting Vanadoborate with New [V10B26] Clusters

An elliptical vanadoborate with a novel V10B26 ratio of the formula [Ni(en)3]3·[1,3-dap]2·H6[V10B26O60(OH)10] (1; en = ethylenediamine, 1,3-dap = 1,3-diaminopropane) was synthesized by a solvothermal method. In the structure, one [V10O30] unit and two [B13O30(OH)5] rings are superimposed alternately to form the V10B26 cluster, which is counterbalanced by the complex Ni(en)32+. In addition, V10B26 clusters interact further with organic molecules through hydrogen bonds, constructing the three-dimensional (3D) open framework with abundant hydrogen-bonding networks. The impedance measurements of compound 1 were carried out; it exhibits a good proton conductivity of 1.78 × 10–3 S cm–1 at 50 °C and 100% relative humidity (RH) and an activation energy of 0.61 eV.