Direct removal of
99
TcO
4
–
from alkaline nuclear
waste is desirable because of the nuclear
waste management and environmental protection relevant to nuclear
energy but is yet to be achieved given that combined features of decent
base-resistance and high uptake selectivity toward anions with low
charge density have not been integrated into a single anion-exchange
material. Herein, we proposed a strategy overcoming these challenges
by rationally modifying the imidazolium unit of a cationic polymeric
network (SCU-CPN-4) with bulky alkyl groups avoiding its ring-opening
reaction induced by OH
–
because of the steric hindrance
effect. This significantly improves not only the base-resistance but
also the affinity toward TcO
4
–
as a result
of enhanced hydrophobicity, compared to other existing anion-exchange
materials. More importantly, SCU-CPN-4 exhibits record high uptake
selectivity, fast sorption kinetics, sufficient robustness, and promising
reusability for removing
99
TcO
4
–
from the simulated high-level waste stream at the U.S. Savannah
River Site, a typical alkaline nuclear waste, in both batch experiment
and dynamic column separation test for the first time.
This feature article reviews the development of functionalized pillararenes as supramolecular materials for lanthanide and actinide separation and heavy metal removal.
A light‐responsive system constructed from hydrogen‐bonded azo‐macrocycles demonstrates precisely controlled propensity in molecular encapsulation and release process. A significant decrease in the size of the cavity is observed in the course of the E→Z photoisomerization based on the results from DFT calculations and traveling wave ion mobility mass spectrometry. These macrocyclic hosts exhibit a rare 2:1 host–guest stoichiometry and guest‐dependent slow or fast exchange on the NMR timescale. With the slow host–guest exchange and switchable shape change of the cavity, quantitative release and capture of bipyridinium guests is achieved with the maximum release of 68 %. This work underscores the importance of slow host–guest exchange on realizing accurate release of organic cations in a stepwise manner under light irradiation. The light‐responsive system established here could advance further design of novel photoresponsive molecular switches and mechanically interlocked molecules.
Luminescent covalent organic frameworks (COFs) find promising applications in chemical sensing, photocatalysis, and optoelectronic devices, however, the majority of COFs are non or weakly emissive owing to the aggregation‐caused quenching (ACQ) or the molecular thermal motion‐based energy dissipation. Here, we report a previously unperceived approach to improve luminescence performance of COFs by introducing isotope effect, which is achieved through substitution of hydrogen from high‐frequency oscillators X‐H (X=O, N, C) by heavier isotope deuterium. Combining the “bottom‐up” and in situ deuteration methods generates the first deuterated COF, which exhibits an impressively 19‐fold enhancement in quantum yield over that of the non‐deuterated counterpart. These results are interpreted by theoretical calculations as the consequence of slower C/N‐D and OD⋅⋅⋅O vibrations that impede the nonradiative deactivation process. The proposed strategy is proved applicable to many other types of emissive COFs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.