The recovery of uranium by hydrometallurgical means involves a liquid-liquid extraction (LLE) step. During this step, the uranium extracted in the aqueous phase after crushing, grinding, and leaching of the rocks is selectively transferred to an immiscible oil phase containing a lipophilic ligand that enables this transfer. As part of the CEA's accelerated program on scientific and technical research for the nuclear energy front-end, this doctoral project aims to complete previous studies carried out at the laboratory on the relationship between the stereochemistry of certain organophosphorus ligands carrying stereogenic centers and their uranium extraction properties. Since these ligands, which are phosphoric diesters or amido- and aminophosphonates, could previously only be obtained under their stereo-enriched form, the Ph. D. student will have to synthesize their diastereopure forms sensu stricto. He will evaluate the affinity of the latter for uranium and their selectivity with respect to competing ions. He will then analyze the molecular and supramolecular mechanisms of each of the diastereoisomers (coordination, aggregation) using state-of-the-art methods such as UV, IR, multinuclear NMR, DFT, X-ray scattering, and neutron scattering. The doctoral program will enable the Ph. D. student to easily join academic or industrial environments, particularly in the fields of the nuclear fuel cycle and separation chemistry. The research will be conducted at the LTSM laboratory of the Marcoule Institute of Separative Chemistry, renowned for its expertise in the chemistry and physical chemistry of extractants for hydrometallurgy. The Ph. D. student will benefit from high-quality supervision and a collaborative working environment, surrounded by Ph. D. students, post-doctoral researchers, and engineers, in a calm and stimulating framework.