The subject of this thesis has been defined with the aim of proposing new liquid-liquid extraction (LLE) processes applicable to the recycling of lanthanides and actinides at downstream of the nuclear fuel cycle. The proposed methodology relies essentially on the availability of lipophilic ligands derived from highly polar chelating agents such as poly(aminocarboxylic) acids (PACA) or hydroxamic acids (HA). As a first step, the PhD student will be involved in a major organic synthesis project, building up a library of several of these different derivatives. During the first phase of the thesis, the candidate will be allowed to develop his activity based on knowledge and results already acquired in this field at LTSM. Concomitantly to this, the candidate will be asked to characterize the extraction properties (affinity and selectivity) of the yielded ligands towards valuable lanthanides and actinides. This will be carried out using well proven approaches, enabling quantitative and qualitative monitoring of ELL performed on a scale of a few milliliters. The candidate will also study the behavior of ligands in organic solution (before and after extraction) by small-angle X-ray scattering (SAXS). During the second phase of the project, he or she will be asked to develop new, more efficient and, in some cases, stereoselective (enantio- and/or diastereoselective) synthesis strategies when several stereoisomers can be obtained. Characterization of both the extraction properties and organic phase behavior of each stereoisomer will allow to describe the extent of the influence of stereoisomery on these properties. Papers will also be written during this second phase. In the third and final phase, the candidate will focus on writing his/her thesis and related articles.The PhD student will be supervised throughout his thesis by two co-directors and a supervisor, who will provide him with multidisciplinary expertise. The candidate's profile should correspond to that of a PhD student already possessing a strong background in organic synthesis and notions of separative and coordination chemistry. Prone to take an interest in liquid-liquid extraction and the colloidal phenomena that accompany the process, the candidate will have acquired skills that will enable him/her to apply for engineering or research positions in the fields of organic chemistry and/or hydrometallurgy.