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.