Very strong and selective complexation of small metal lons by a highly preorganised open-chain bispidine-based ligand

Synthesis of 3,7-bis(2-pyridylmethyl)-3,7-diazabicyclo[3.3.1]nonane DPB, with very rigid nitrogen-bridge reinforcement gives an adamantane-like structure once a metal ion is coordinated to DPB, and shows how remarkable stability enhancement and selectivity for metal ions on the basis of size can be achieved in non-macrocyclic ligands.