This invention provides chelating moieties that comprise an aryl group. Monomers that include the chelating moieties can be polymerized into chelating polymers. Chelating polymers are useful to chelate metals. Chelating polymers in the form of metal chelates are useful for binding analytes, such as polypeptides that comprise histidine residues. Chelating polymers can be includes in articles such as chips and chromatographic materials.