Metal-ligand induced supramolecular polymerization: a route to responsive materials.

The use of metal-ligand binding as the driving force for the self-assembly polymerizations of a ditopic ligand offers a facile route to the preparation of organic/inorganic hybrid materials. Such metallo-supramolecular polymers potentially offer the functionality of the metal ion along with the processibility of a polymer. We report, herein, the preparation of gel-like metallo-supramolecular polymers prepared from a monomer unit, which consists of a 2,6-bis-(benzimidazolyl)-4-hydroxypyridine unit attached to either end of a polyether chain, mixed with a lanthanoid metal (e.g. La(III), Eu(III)) and a transition metal ion (e.g. Co(II) or Zn(II)). Such materials show dramatic reversible responses to a variety of stimuli, including thermal, mechanical, chemical and light. The nature of the response can be controlled by the nature of the combination of transition metal ion and lanthanoid metal ion used.