Mechanically interlocked molecules such as rotaxanes and catenanes have recently begun to attract increased interest as scaffolds for the development of new catalysts. The key features of the mechanical bond that suggest this is a promising avenue for research are the ability of the components to undergo large amplitude motion, the potential for multiple cooperating functional groups to be projected into the cavity created by the mechanical bond, the sterically crowded environment of the mechanical bond itself 18 including the potential for the mechanical bond to direct reactions that otherwise would not occur without the steric confinement it provides, and the potential for enantioselective interlocked catalysts to rely on molecular chirality that arises due to the symmetry properties of the mechanical bond itself. Here we report the development of rotaxane-based highly selective anion-π catalysts that, due to the cooperation of several convergent functional groups and the confined environment of the mechanical bond, deliver remarkably high selectivity in one of the benchmark reactions of the field, the Michael addition of a malonic acid half-thioester (MAHT) to β-nitrostyrene. 9d Although all of the catalysts presented contain an NDI-based axle, a recurring motif in anion- catalysis, experimental and computational data suggest the selectivity of the best catalysts is due to the polarizability of a π-stacked structure formed by interaction of a bipyridinium moiety and the NDI unit, with the bipyridinium unit, in some cases, providing the π surface that interacts directly with the substrate.