Room temperature sol–gel synthesis of crystalline Cs[V₃O₈]. Probing the hydration level of the interlamellar space by ⁵¹V and ¹³³Cs MAS NMR spectroscopy

The caesium vanadium oxide phases Cs[V₃O₈] and Cs₂[V₆O₁₆]·0.7 H₂O were synthesized by a room temperature process, a promising alternative method to traditional routes to MV₃O₈ phases. The characterization of these compounds and Cs₄[H₂V₁₀O₂₈]·4H₂O by powder X-ray diffraction, SEM and solid-state NMR is provided. In particular, we used ⁵¹V and ¹³³Cs MAS NMR to investigate the local environment of caesium and vanadium nuclei and 2D ¹H → ¹³³Cs CP MAS HETCOR experiments to explore the spatial connectivities between caesium ions and water molecules in the interlamellar space. The results obtained on Cs₂[V₆O₁₆]·0.7 H₂O illustrate how powerful solid-state NMR can be to study structurally disordered materials.