Metal phosphonates incorporating metalloligands: assembly, structures and properties

Metal phosphonates are an important class of metal-organic hybrid materials that exhibit versatile structures, intriguing functions and high water and thermal stability. Despite a large number of metal phosphonates achieved over the past few decades, those incorporating metalloligands are rather limited. The metalloligand approach can provide a unique opportunity in constructing homo- or mixed-metal coordination polymers with rationally immobilized functional moieties for various applications in gas storage and separation, heterogeneous catalysis, sensing and multifunctional materials. In this feature article, we shall introduce the current status of a special subclass of metal phosphonates, namely, metal-metalloligand phosphonates (MMPs), including synthetic strategies, crystal structures, and properties of those based on paddlewheel diruthenium, metallo-polyazamacrocycle, metalloporphyrin and metallo-tris-bipyridine ligands. Future challenges in this field are discussed.