Abstract: The recognition of metal ions from complex matrices presents daunting challenges. Conventional approaches of ion-exchange and chelation employing liquid-liquid or solid-liquid methods cannot adequately address these challenges. Our hypothesis is that metal chelation sites placed in predetermined sites in organized molecular self-assemblies can selectively separate target metal ions in contrast to their presence in random macroenvironments in the conventional approaches. We have dsesinged and synthesized several molecular assemblies in the nanometer to micrometer dimensions such as micelles, vesicles, and imprinted polymers which exhibit high selectivities in metal ion separations. Such systems have been characterized through their spectroscopic properties, and by separation studies using HPLC and capillary electrophoresis. These studies will be described.