Co-ordination polymers

This paper is a review of the metal complex forming coordination polymers. A polymer-metal complex is composed of synthetic polymer and metal ions bound to the polymer ligand by a coordinate bond. A polymer ligand contains anchoring sites like nitrogen, oxygen or sulphur obtained either by the polymerization of monomer possessing the coordinating site or by a chemical reaction between a polymer and a low molecular weight compound having the coordinating ability. The polymer-metal complexes may be classified into different groups according to the position occupied by the metal, which is decided by the method of preparation. The method include the complexation of polymeric ligand with various metal ions, cross-linked polymers with pendent, ligands forming either intramolecular and/or intermolecular chelating functions are highlighted in the first part. The various works on the coordination complexes has revealed that the heterogeneous systems possess more economical potentials and advantages over homogeneous systems. The co-ordination polymers belong to the former case. The high molecular weight polymer-metal complexes work as storage houses for solar energy. Efficient chemical conversion in the storage of solar energy will be difficult with the homogeneous systems. The synthesis results in an organic polymer with inorganic functions. The metal atoms attached to the polymer backbone are bound to exhibit characteristic catalytic behaviour, which are distinctly different from their low molecular weight analogue. Many synthetic polymer-metal complexes, found to possess high catalytic efficiency, in addition to ion selectivity in waste water treatment, recovery of trace metal ions, and hydrometallurgy are enlightened in the final part. (C) 2000 Elsevier Science Ltd. All rights reserved.