Geometrically and chemically dual-adaptive COFs for selective recognition of multiple uranium species in complex waters

Sustainable uranium supply is critical for nuclear energy, yet its practical recovery is severely hindered by the chemical complexity of uranium in natural waters. In dynamic aqueous environments, uranium continuously shifts between large, cationic hydrolyzed clusters (acidic/neutral) and compact, anionic carbonate complexes (alkaline). Conventional static adsorbents fail to accommodate these contrasting charges and geometries. Here, we report a geometrically and chemically dual-adaptive three-dimensional covalent organic framework (COF), TAM-DTDA-AMM, to overcome this speciation barrier. Featuring a three-fold interpenetrated dia topology, the functional COF enables environment-driven reversible −COO−···NH4+ ion-pair reconfiguration, coupling adaptive pore-surface chemistry with dynamic spatial confinement. Under alkaline environments, cationic microdomains stabilize [UO2(CO3)3]4− via electrostatic and hydrogen-bonding interactions, whereas under near-neutral to acidic conditions, protonated carboxyl groups directly coordinate hydrolyzed uranyl clusters. This dual-adaptive mechanism enables rapid, selective, and high-capacity uranium extraction across diverse aqueous chemistries and offers a general strategy for recognizing multiple metal species in complex environments. Uranium recovery is hindered by the chemical complexity of uranium ions in natural waters. Here the authors report a geometrically and chemically dual-adaptive three-dimensional covalent organic framework which enables rapid and selective uranium-extraction across diverse aqueous chemistries.