N-heterocycle compounds are the crucial scaffolds present in natural products, synthetic molecules, agricultural chemicals, and pharmaceuticals. Hence, the development of green catalytic systems for constructing N-heterocycles has been a focused topic in organic synthesis and industrial catalysis. Polyoxometalates (POMs) are polynuclear metal–oxygen clusters with structural diversity and physicochemical properties. POMs possess advantageous properties such as adjustable acidity, redox properties, high thermal stability, and non-toxic nature. Therefore, POMs have been widely investigated for their application in N-heterocycles synthesis and hold great potential for industrial applications. In this review, we summarized recent progress (mainly from 2010 to 2023) in the N-heterocycles synthesis catalyzed by heteropolyacids (HPAs), modified HPA catalysts, and transition metal-modified POMs. The synthesized N-heterocycles include pyrroles, indoles, pyridines, and benzodiazepines, among others. Furthermore, the prospects of POMs-based catalytic systems of N-heterocycles were also proposed.

Uranium-containing polyoxometalates (U-POMs), an important class of actinide cluster compounds, are the products of the assembly of uranium or uranium and POMs. These cluster compounds illustrate the structural beauty and diversity of obtained U-POMs that can be achieved by the reaction of uranium or uranium and POMs. The structural diversity is revealed by the classification of U-POMs in this review, which are mainly divided into two parts, according to the main metal elements of the clusters, named U-containing heteropolyoxometalates (U-hetero-POMs) and U-oxo-clusters. U-hetero-POMs are further classified by development date from the end of the 20^th century based on the basic building units, including Keggin-type, Dawson-type, Silverton-type, hybrid structures, and cryptand structures. U-oxo-clusters mainly include uranyl peroxide clusters, their derivatives, and U^IV-oxo-clusters and mixed-valence U-oxo-clusters. This review provides a comprehensive summary of the synthesis and structures of U-POMs as well as their characterization, properties, and applications. Finally, the development prospects and directions for U-POMs in the future are also elucidated.