Highly Selective Lithium Transport through Crown Ether Pillared Angstrom Channels

Biological ion channels use the synergistic effects of various strategies to realize highly selective ion sieving. For example, potassium channels use functional groups and angstrom-sized pores to discriminate rival ions and enrich target ions. Inspired by this, we constructed a layered crystal pillared by crown ether that incorporates these strategies to realize high Li+ selectivity. The pillared channels and crown ether have an angstrom-scale size. The crown ether specifically allows the low-barrier transport of Li+. The channels attract and enrich Li+ ions by up to orders of magnitude. As a result, our material sieves Li+ out of various common ions such as Na+, K+, Ca2+, Mg2+ and Al3+. Moreover, by spontaneously enriching Li+ ions, it realizes an effective Li+/Na+ selectivity of 1422 in artificial seawater where the Li+ concentration is merely 25 mu M. We expect this work to spark technologies for the extraction of lithium and other dilute metal ions. A bioinspired device that can sieve Li+ out of concentrated Na+ with high selectivity is constructed. The device is composed of angstrom channels that can enrich small cations and pillaring macrocycles that have specific interaction with alkaline ions. In solutions with the concentrations of Li+ and Na+ equal to those in seawater, the effective Li+ selectivity reaches 1422.+image