Relative anion binding affinity in a series of interpenetrated coordination cages.

Previously, we have reported on the quantitative self-assembly of a series of interpenetrated double-cages [Pd4Ligand8] with ligands based on various organic backbones. For dibenzosuberone-based cages it was shown that anion binding in the outer two pockets follows an allosteric mechanism. Herein we wish to report the anion binding capabilities of three related phenothiazine cages. We present a systematic comparison of the relative halide (Cl(-) and Br(-)) binding affinities and the structural rearrangements of four double-cages based on NMR titrations, NOESY experiments and electronic structure calculations.