"Ion separation" is one of the major problems associated with the technologies for energy production, nuclear or alternative, from the mining extraction to the processing of spent fuel, in an attempt of securing the storage of ultimate wastes and of recycling the recoverable materials. All materials contain metals that have to be separate after dissolution. LTSM provides its competence and expertise in organic synthesis for the development of innovative molecules for the separation chemistry, in the fields of nuclear energy, chemistry (from the upstream to the reprocessing nuclear fuel), and extraction / recycling of strategic metals. These studies require the development of synthesis methodologies followed by the use of characterization methods, preliminary studies of extraction at the laboratory scale, and then an optimization of the molecular architectures if needed. However, the optimization of these molecules is not possible if the mechanisms involved during liquid-liquid extraction process are not known. Hence, using a molecular and supramolecular approach of the systems involved in the liquid-liquid extraction, and thanks to its skills in physical chemistry concerning the self-assembled systems in complex fluids, LTSM contributes to the study of the extraction mechanisms, e.g., synergistic mechanisms and/or by self-assembly.