A 3D metal-organic network, [Cu2(glutarate)2(4,4'-bipyridine)], that exhibits single-crystal to single-crystal dehydration and rehydration.

The reaction of Cu(NO3)2, glutaric acid and 4,4'-bipyridine in water affords a novel 3D coordination polymer which exhibits reversible desorption and adsorption of water molecules with retention of single crystallinity.