Uranyl Recognition through Cucurbit[7]uril-Bipyridinium Carboxylate Pseudorotaxanes as Supramolecular Chelators

Exploration of new ligands for actinide recognition is desirable for developing more efficient separation processes, and pseudorotaxane-type supramolecular complexes have the attributes of simple synthesis and structural adaptability. In this work, we propose two novel CB[7]-based bipyridinium carboxylate pseudorotaxane ligands and evaluate their potential as efficient chelators for uranyl recognition. A combination of characterization methods including nuclear magnetic resonance (NMR), fluorescence analysis, mass spectrometry (ESI-MS), infrared spectroscopy (IR), and single-crystal X-ray diffraction (SCXRD), together with theoretical calculation, demonstrates the feasibility of such a kind of pseudorotaxane chelator for uranyl recognition via host-guest synergistic chelation. This work establishes a new type of cucurbituril-carboxylate supramolecular chelator and will inspire the development of more other supramolecular ligands for actinide recognition.