Nanoconfinement Effect: A Dynamic and Powerful Halide-Sequestrating Pd2L4 Cage

Inspired by the dehalogenase enzyme’s remarkable ability to cleave the stronger carbon-halogen bonds, we demonstrate unprecedented C−Cl bond scission using a halide-binding synthetic host. We achieved this by employing a precisely designed Pd2L4-type coordination cage equipped with Pd(II)−ligand bond dynamics and a tailor-made cage cavity with noncovalent binding forces for high-affinity anion-binding. This cage is one of the strongest chloride-binding synthetic hosts (Ka(Cl) > 1010 M−1) known in polar solvent medium. It also demonstrates at least two orders of magnitude higher chloride affinity than halophilic Ag(I) in acetonitrile. One of the fascinating features of this well-defined cage is its ability to cleave B−F/C−Cl bond in a facile manner from BF4/chlorinated solvents in nonpolar solvent media. We propose a partial cage dissociative mechanistic pathway based on experimental evidences for cage-promoted carbon−halogen bond scission.