Imidazole-based metal-organic cages: Synthesis, structures, and functions

The coordination-driven self-assembly provides a favourable methodology for constructing metal–organic architectures with diverse structures and functions. As a classical five-membered heterocyclic ligand, imidazole is widely used in the construction of metal–organic materials with finitely and infinitely structures. In this review, the synthetic methods of imidazole-based metal–organic cages (IMOCs) are introduced and analysed. Subsequently, various type of IMOCs with structure and coordination diversity of imidazole and its polytopic derivatives, including tetrahedron, cube, octahedron, rhombic dodecahedron, tetartoid, bicapped square antiprism, prism, etc., have been rationally categorised by using edge- and face-directed self-assembly strategies. Moreover, the functional applications of these IMOCs, including host–guest chemistry, luminescence, magnetism, catalysis, biological effect, and proton conductivity, are also comprehensively summarized. The relationship between structures and properties of IMOCs are elucidated and concluded, which provides some inspiration for designing new metal–organic cages with advanced functions.