Ultra-highly selective trapping of perrhenate/pertechnetate by a flexible cationic coordination framework

The selective binding and trapping of perrhenate/pertechnetate is of great interest in the contamination remediation of nuclear waste. Herein, we report a cationic metal-organic framework (TJNU-216, TJNU = Tianjin Normal University), with ultra-high selectivity in trapping perrhenate/pertechnetate in the presence of a large excess of SO42- (20 000 times) or NO3- (300 times), and the highest exchange capacity of 417 mg g-1 (1 mol mol-1). The exchange mechanism can be confirmed by the crystal structure of TJNU-216(Re) via single-crystal-to-single-crystal transformation.