Unprecedented 3D polycatenation based on ribbons of rings found in two metallosupramolecular polymers whose open frameworks show reversible collapse upon de- and rehydration

Two isostructural metallosupramolecular polymers [M(H₂O) ₄-(BCbpy)₂]₂Cl₄·18H ₂O [M = Co(ii), Ni(ii); HBCbpyCl = 1-(4-carboxybenzyl)-4,4′- bipyridinium chloride] have been synthesized by the self-assembly reaction of HBCbpyCl salt with MCl₂ (M = Co, Ni). The unprecedented catenation of the (1D → 3D) type based on ribbons of rings is found in both supramolecular networks. Interestingly, this catenation mode can help generate channels, and the resulting supramolecular frameworks show recoverable collapse upon de- and rehydration, making them good potential adsorbents of water vapor.