Tripodal Organic Cages with Unconventional CH···O Interactions for Perchlorate Remediation in Water

Perchlorate anions used in industry are harmful pollutants in groundwater. Therefore, selectively binding perchlorate provides solutions for environmental remediation. Here, we synthesized a series of tripodal organic cages with highly preorganized C_sp3-H bonds that exhibit selectively binding to perchlorate in organic solvents and water. These cages demonstrated binding affinities to perchlorate of 10⁵-10⁶ M^-1 at room temperature, along with high selectivity over competing anions, such as iodide and nitrate. Through single crystal structure analysis and density functional theory calculations, we identified unconventional C_sp3-H···O interactions as the primary driving force for perchlorate binding. Additionally, we successfully incorporated this cage into a 3D-printable polymer network, showcasing its efficacy in removing perchlorate from water.