Cyclotriphosphazene‐Centered Ligands in Metal–Organic Frameworks: Structural Diversity and Functional Applications

The chemistry of cyclotriphosphazene‐based metal–organic frameworks (MOFs) has advanced significantly, yielding multifunctional materials whose influence now spans a wide range of scientific disciplines. The phosphorus centers within the cyclotriphosphazene (P 3 N 3 ) ring alternate with nitrogen atoms, forming a stable planar structure in which each phosphorus atom is coordinated to two chlorine atoms. These phosphorus sites serve as versatile reactive centers capable of anchoring a variety of functionalized ligands. Through nucleophilic substitution, diverse functional groups can be tethered to the ring via POC linkages, enabling the design of an extensive library of oxygen‐spacer ligands, including several hexakis‐substituted carboxylatophenoxy derivatives and other functionalized cyclotriphosphazene derivatives. Using these ligands as organic linkers, MOFs have been synthesized with metals spanning the s‐, p‐, d‐, and f‐block elements, giving rise to a wide variety of structural architectures. This review highlights these ligand–metal combinations, the resulting coordination environments, geometric features, and topological frameworks. Furthermore, cyclotriphosphazene‐based MOFs reported across 1D, 2D, and 3D systems are discussed in the context of their diverse applications, including catalysis, sensing, adsorption, separation, and dye degradation.