The present disclosure provides novel solid sorbents synthesized by the reaction of polyamines with polyaldehyde phosphorus dendrimer (P-dendrimer) compounds for metal sequestration. The sorbents are highly stable and exhibit desirable thermodynamics and reaction kinetics with a wide variety of metals including heavy metals and rare earth elements. The sorbents can be easily regenerated for repeated use to extract metals from an aqueous solution. The materials are stable to aqueous and organic media, as well as strong acid and bases. The sorbents maintain full capacity over many cycles of use.