The anion-binding polyanion: a molecular cobalt vanadium oxide with anion-sensitive visual response

Abstract

An anionic molecular cobalt vanadium oxide cluster, (n-Bu₄N)₃[Co(AcO)V₄O₁₂] and its use as anion binding site is reported. Cluster formation is controlled by an anion-dependent dynamic solution equilibrium. Reversible anion binding in solution leads to significant spectral changes, allowing the ratiometric optical detection of the anion concentration in situ, even under harsh thermal conditions (T = 90 °C). Comparative studies showed that the spectral response is dependent on the type of anion so that carboxylates, weakly coordinating anions and halides can be distinguished.