Discovery of Powerful Uranyl Ligands from Efficient Synthesis and Screening

New tripodal gem‐(bis‐phosphonates) uranophiles were discovered by a screening method that allowed for the selection of ligands with strong uranyl‐binding properties in a convenient microtiter‐plate format. The method is based on competitive uranium binding by using Sulfochlorophenol S as chromogenic chelate. This dye compound was found to present high uranyl complexation properties and allowed to highlight ligands presenting association constants for ${{\rm UO}{{2+\hfill \atop 2\hfill}}}$ up to 1018 at pH 7.4 and 1020 at pH 9. A collection of 40 known ligands including polycarboxylate, hydroxamate, catecholate, hydroxypyridonate and hydroxyquinoline derivatives was tested. Also screened was a combinatorial library prepared from seven amine scaffolds and eight acrylates bearing diverse chelating moieties. Among these 96 tested candidates, a tripod derivative bearing gem‐bis‐phosphonates moieties was found to present the highest complexation properties over a wide range of pH and was further studied. A dye compound allows the high‐throughput screening of uranyl ligands even by simple visualization by the naked eye. 96 candidate ligands were screened and the results highlighted (see figure) the remarkable uranium‐binding properties of ligands bearing bis‐phosphonate moieties.