Fully-stretched, single-crystalline polymers of linear poly[n]catenanes

Making single crystals of fully stretched polymers is an outstanding challenge because polymers generally crystallize by chain folding. We report a strategy termed "phantom templation," wherein the metal templates the formation of poly[n]catenanes but is not found in the crystalline product. Based on this strategy, we synthesized the highly sought after linear poly[n]catenanes with molecular weight of 4.5 megadaltons and degree of polymerization of 2,800—over 100 times higher than previous records. Generally, post-synthetic demetalation leads to non-crystalline solids; a challenge addressed by the in situ nature of phantom templation. This also allowed the installed anthracene units to organize through π-π stacking and chain-to-chain packing, giving single crystals of linear poly[n]catenanes as structurally determined by transmission electron microscopy and x-ray diffraction techniques.