Hierarchical Self-Assembly of Lactams into Supramolecular CO-Spiked “Sea Urchins” and Then into a Channeled Crystal

Cobalt complexation of the two alkynes of a de novo designed dimeric lactam triggers a complete reorganization of the lactam ring through formation of a β-turn-like motif. Self-assembly with concomitant induced fit of six monomers yields a globular quaternary structure shaped like an ellipsoid. This final architecture generates a peculiar molecular electrostatic potential field, with both pole caps being negatively charged while the equatorial region is mostly positive. Further packing, at least partially controlled by these electrostatic effects, leads to a superquaternary structure, a porous crystal, in which the many intercommunicating negatively charged channels occupy as much as 24% of the whole crystal.