Stimuli-responsive hydrogels prepared by simultaneous "click chemistry" and metal-ligand coordination

A novel strategy to synthesize stimuli-responsive metal-coordinated polymeric gels (MCPGs) via one-pot CuAAC and non-covalent metal coordination chemistry was demonstrated. 4'-(4-Prop-2-ynyloxyphenyl)-2,2 ':6 ',2 ''-terpyridine (Terpy-phi-CH2C equivalent to CH) and alpha,omega-diazido/hydroxyl PEG (PEG(45)(N-3)(2)) were used as precursors to yield linear terpyridine-terminated PEG derivatives with 1,2,3-triazole rings and terpyridine ligands in their main chains to serve as ligands for chelating a range of transition and/or lanthanide metal ions. It was found that the bridging metal complexes could not only act as branching or crosslinking sites within the three-dimensional polymer networks but could also bestow special properties to the final gels, such as stimuli-responsive and thixotropic features, thereby allowing facile and efficient design and synthesis of promising intelligent materials.