Herein, we present an exceptional structural transformation from a porous supramolecular network to a porous coordination polymer. The transformation involves a change of interpenetrating dimensionality from 6-fold to 5-fold. Simultaneously, the spin state of nickel(ii) is altered from S = 0 to S = 1, which is concomitant with the formation of the Ni-O(carboxylate) coordination bonds.