Efficient lithium extraction from brines using a crown-like ether with multichannel binding mechanisms

Lithium is indispensable to modern technology, making efficient lithium extraction from brine increasingly critical. We report a crown-like ether, 2,2′-(propane-1,3-diylbis(oxy))diphenol (PDD), as a high-performance material for lithium extraction. Compared to dibenzo-14-crown-4 (DB14C4), PDD offers a simplified synthesis, a higher yield (∼80 %), and significantly reduced solvent loss (∼1/11 of DB14C4). Beyond retaining the essential crown-ether framework that capable of coordinating with Li⁺ through electrostatic and size-sieving effects, PDD introduces multiple highly electronegative Ar–OH groups that serve as additional high-affinity binding sites for Li⁺. This multi-channel extraction mechanism represents a new paradigm in lithium coordination. As a result, PDD exhibits superior lithium-extraction performance. In simulated brine (Mg:Na:Li = 75:11:0.8, mass ratios), the Li⁺/Mg²⁺ and Li⁺/Na⁺ separation factors for PDD were 5.2 and 6.2, respectively. These findings highlight PDD as a low-cost, efficient, and environmentally benign material, offering a promising strategy for sustainable lithium supply.