A new
proton-conducting material (C6H14N2)[NiV2O6H8(P2O7)2]·2H2O (1) was hydrothermally
synthesized by using 1,4-diazabicyclo[2,2,2]octane (DABCO) as the
template. Its inorganic framework, determined by single crystal X-ray
diffraction, is constructed by the connection of V/NiO6 octahedral to P2O7 pyrophosphate units through
sharing oxygen atoms, giving rise to three-dimensional (3D) intersecting
6-, 8-, and 12-ring channels along the [100], [010], and [001] directions,
respectively, in which there are ordered protonated DABCO cations
balancing negative charge of the framework and disordered water molecules.
Complex impedance measurements on polycrystalline samples gave proton
conductivities of 4.9 × 10–3 and 2.0 ×
10–2 S cm–1 at 25 and 60 °C
under high humidity conditions, respectively. The activation energy
is 0.38 eV.