Vanadoborates: cluster-based architectures, preparation and properties

Abstract

Crystalline polyoxovanadates (POVs) are a subclass of polyoxometalates with significance in chemical, physical and materials sciences. Recent studies revealed that the condensation of vanadate and borate fragments may yield a whole new class of POVs. These novel vanadoborates are typically prepared by high-temperature solid-state, boric acid flux or low-temperature hydrothermal techniques. The different connections of [VO_x] (x = 4, 5, 6) and [BO_x] (x = 3, 4) polyhedral units ultimately result in a fascinating variety of vanadoborate anionic clusters, which can be at the genesis of a myriad of one-dimensional (1-D), two-dimensional (2-D) and three-dimensional (3-D) polymeric architectures by way of either self-condensation or by forming covalent bonds with other metal ions or unsaturated metal complexes. This review summarizes, in a systematic structural approach, the most striking advances in the syntheses, structural features, and some properties of crystalline vanadoborates based on different [V_xB_y] and [V_xB_yP_z] clusters. It intends to provide meaningful and helpful guidance for the future preparation of new and functional vanadoborates.