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.