Vanadium-substituted polycationic Al-oxo cluster in a porous ionic crystal exhibiting Lewis acidity

Abstract

Herein we present the first example of a vanadium-substituted δ-Keggin Al₁₃-based (Al₂₈V₄) porous Ionic crystal (PIC) (Al₂₈V₄-PW₉V₃). Structural and theoretical studies suggested that Al₂₈V₄ may exhibit Lewis acidity, which was confirmed by acetalization reaction with Al₂₈V₄-PW₉V₃ as a solid catalyst and investigations with pyridine or 2,6-lutidine as basic probe molecules. A comparative study with the δ-Keggin Al₁₃ monomer based PIC indicated that the vanadium-substitution gave rise to the Lewis acidity.