LiCl recovery with a one-point-enhanced crown ether as an efficient phase-transfer agent.

Efficient LiCl recovery directly from natural resources remains challenging due to the strong hydration of Li+ and the high lattice energy of crystalline LiCl. Solid-state extraction of LiCl requires efficient extractants capable of forming stable LiCl complexes that can be selectively separated from solid matrices. Here we report that phosphine oxide-containing crown ether 1 acts as a flexible one-point-enhanced extractant capable of selectively extracting LiCl from mixtures of alkali metal chlorides. The capture process is supported by a PO donor site embedded within the crown ether framework, providing a coordination environment suitable for selective LiCl recognition. Importantly, the resulting 1-LiCl complex undergoes rapid release of LiCl into water under mild conditions. This ambivalent capture-release behavior enables selective LiCl phase transfer from solid mixtures into water and provides a molecular platform for reversible lithium chloride recognition and release.