Metal phosphonate hybrid materials: from densely layered to hierarchically nanoporous structures

Metal phosphonate materials are promising non-siliceous inorganic-organic hybrids that are synthesized by combining metal joints and organophosphonic linkages at the molecular scale. The mild conditions for metal phosphonate synthesis, their homogeneous composition and the combined merits of inorganic units and organic groups have permitted the rational design and incorporation of various functionalities through constituent building units. In this critical review, we present the development and recent advances related to the field of metal phosphonates and the relevant nanocomposites. The possibility to integrate the functionalities from both inorganic and organic moieties is discussed. The incorporation of well-defined porosity and capacity for post-modification have extended the application potential to the area of adsorption, separation, catalysis, environmental intervention, energy storage and biology. Metal phosphonates thus present an unprecedented opportunity for the rational and precise design of sophisticated materials with multifunctionality.