Universität Wien, Fakultät für Chemie, Institut für Biophysikalische Chemie, Althanstr. 14, 1090 Vienna, Austria.
Chem Soc Rev. 2020 Nov 7;49(21):7568-7601. doi: 10.1039/d0cs00392a. Epub 2020 Sep 29.
Polyoxometalates (POMs) are a large group of anionic polynuclear metal-oxo clusters with discrete and chemically modifiable structures. In most aqueous POM solutions, numerous, and often highly negatively charged, species of different nuclearities are formed. It is rather difficult to determine the dominant POM species or their combination, which is responsible for the specific POM activity, during a particular application. Thus, the identification of all individual speciation profiles is essential for the successful implementation of POMs in solution applications. This review article summarizes species that are present in isopoly- and heteropolyvanadates, -niobates, -molybdates and -tungstates aqueous solutions and covers their stability and transformations. The ion-distribution diagrams over a wide pH range are presented in a comprehensive manner. These diagrams are intended for the targeted use of POMs, and in a clear form shows species that are in equilibrium at the given pH value. Thus, the data accumulated in this review can serve as both a starting point and a complete reference material for determining the composition of POM solutions. Some examples are highlighted where the POM speciation studies led to a detailed understanding of their role in applications. In doing so, we aim to motivate the POM community for more speciation studies and to make the subject more comprehensible, both for synthetic POM chemists and for scientists with different backgrounds interested in applying POMs in biological, medical, electrochemical, supramolecular and nanochemistry fields, or as homogeneous catalysts and other water-soluble materials.
多金属氧酸盐（POMs）是一大类具有离散和可化学修饰结构的多核金属氧簇阴离子。在大多数多酸水溶液中，会形成许多不同核电荷数的、通常带高度负电荷的物种。在特定应用中，确定起主要作用的多酸物种或其组合非常困难，而这些物种或组合决定了多酸的特定活性。因此，确定所有单个形态分布对于成功实施多酸在溶液中的应用至关重要。本文总结了同多和杂多钒酸盐、铌酸盐、钼酸盐和钨酸盐水溶液中存在的物种，并涵盖了它们的稳定性和转化。在很宽的 pH 范围内以综合的方式呈现离子分布图。这些图表旨在有针对性地使用多酸，并以清晰的形式显示在给定 pH 值下处于平衡状态的物种。因此，本文综述中积累的数据既可以作为确定多酸溶液组成的起点，也可以作为完整的参考资料。本文还强调了一些示例，其中多酸形态研究导致对其在应用中作用的详细理解。通过这样做，我们旨在激励多酸领域进行更多的形态研究，并使该主题对于不同背景的科学家来说更易于理解，无论是对合成多酸化学感兴趣的科学家，还是对将多酸应用于生物、医学、电化学、超分子和纳米化学领域、作为均相催化剂和其他水溶性材料感兴趣的科学家。
