Phosphine-functionalized metal-organic frameworks: synthesis, structures and applications

The integration of phosphine chemistry into metal-organic frameworks (MOFs) remains challenging due to the sterically bulky, non-planar geometry and air-sensitive nature of the phosphine group. However, phosphine-functionalized metal-organic frameworks (P-MOFs) have emerged as promising platform that combine the advantages of phosphine coordination chemistry with the structural tunability and porosity of reticular materials. Although phosphine ligands are omnipresent in homogeneous organometallic catalysis due to their tunable electronic and steric properties, phosphine based compounds still remains at an early stage, because of challenges associated with ligand bulkiness, non-planar geometry, and air sensitivity. This review summarizes recent advances in the synthesis, structural features, and diverse applications of P-MOFs. Two main synthetic strategies, including direct synthesis using phosphine-containing ligands and post-synthetic modification, are critically evaluated. In-depth discussion has been made on how the sterically bulky, non-planar, and air-sensitive phosphines are incorporated inside the framework and their influence on MOF stability and functionality. Diverse applications are discussed in detail in terms of phosphine ligand structure-function relationship, including the potential challenges for future development. Finally, we discuss the possible solutions, including new types of reactions and techniques as perspectives for the development of P-MOF applications, highlighting the opportunities and challenges. Till date, more than fifty P-MOFs have been designed and synthesized for potential applications in heterogeneous catalysis, molecular sensing, gas sorption, and many other important applications. Such rapid publications demand an ordered grouping for at a glance understanding.