Abstract
The removal of anions from aqueous media using molecular receptors in liquid-liquid extraction is a long-standing strategy to clean up contaminated water sources. Therein, high selectivity is needed to remove specific ions from mixtures of other ions, and high affinity provides extractions at low concentrations. However, the high affinity creates a conundrum by impeding the release of the ions in any stripping steps needed for further processing. To circumvent this problem, light-responsive receptors have been proposed as candidates for turning off the binding, but they are currently untested in liquid-liquid extraction. We tested the feasibility of light-driven release using a cyanostar macrocycle. We demonstrate the selective extraction of PF6- anions over large excesses of competing anions (Cl-, NO3-, SO42-) followed by photodriven release for quantitative isolation of the target. Release relies on photoisomerization of the macrocycle’s five stilbenes generating distorted isomers to turn off binding. With modest reversibility, only a single-shot release was demonstrated, akin to photodriven uncaging. These methods were extended to the capture and photodriven release of ReO4- and radioactive 99TcO4- anions at ∼90% efficiency. Extraction was demonstrated down to the highly dilute 4 ppb levels of the 99TcO4- anion. This proof-of-concept demonstration verifies the use of a large change in affinity for the all-to-nothing capture and release of target anions between liquid phases.
| Original language | English |
|---|---|
| Pages (from-to) | 15707-15718 |
| Number of pages | 12 |
| Journal | Journal of the American Chemical Society |
| Volume | 147 |
| Issue number | 18 |
| DOIs | |
| State | Published - May 7 2025 |
Funding
N.B., A.L., Z.Z., A.R.M., and A.H.F. acknowledge support from the Chemical Sciences, Geosciences, and Biosciences Division of the Basic Energy Sciences Program of the U.S. Department of Energy Office of Science (DE-SC0002728). J.D.E. and S.J.P. acknowledge support from the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division (DE-SC00ERKCC08) for anion separations work and the U.S. Department of Energy, Office of Nuclear Fuel Cycle and Supply Chain, Material Recovery and Waste Form Development Campaign (NE-43) for radioisotopes. Z.Z. acknowledges support from the Kindig Fellowship. We acknowledge the use of the 500 MHz spectrometer used in this research that was generously supported by NSF grant CHE-1920026. The prodigy probe was partially funded by the Indiana Clinical and Translational Sciences Institute. Support for the acquisition of the Bruker Venture D8 diffractometer through the Major Scientific Research Equipment Fund from the President of Indiana University and the Office of the Vice President for Research is gratefully acknowledged. We thank Elisabeth Fatila for contributing the clamshell receptors used in this work. We thank Bruce Moyer for the discussions on the extraction of TcO4-. We thank Bo Albinsson for help using triplet sensitizers in a bid to convert the photoisomerized cyanostar into the all-trans state. N.B., A.L., Z.Z., A.R.M., and A.H.F. acknowledge support from the Chemical Sciences, Geosciences, and Biosciences Division of the Basic Energy Sciences Program of the U.S. Department of Energy Office of Science (DE-SC0002728). J.D.E. and S.J.P. acknowledge support from the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division (DE-SC00ERKCC08) for anion separations work and the U.S. Department of Energy, Office of Nuclear Fuel Cycle and Supply Chain, Material Recovery and Waste Form Development Campaign (NE-43) for radioisotopes. Z.Z. acknowledges support from the Kindig Fellowship. We acknowledge the use of the 500 MHz spectrometer used in this research that was generously supported by NSF grant CHE-1920026. The prodigy probe was partially funded by the Indiana Clinical and Translational Sciences Institute. Support for the acquisition of the Bruker Venture D8 diffractometer through the Major Scientific Research Equipment Fund from the President of Indiana University and the Office of the Vice President for Research is gratefully acknowledged. We thank Elisabeth Fatila for contributing the clamshell receptors used in this work. We thank Bruce Moyer for the discussions on the extraction of TcO. We thank Bo Albinsson for help using triplet sensitizers in a bid to convert the photoisomerized cyanostar into the all- trans state. 4