Two supramolecular microporous frameworks stabilized by hydroxyl anionic water cluster

Two stable supramolecular microporous framework complexes, from the same [MCl(phen)2]+ (M = Cu, Ni), containing chiral hydroxyl anionic water cluster polymer, were synthesized, and their crystal structures were described. These supramolecular frameworks showed very high stability even if they were heated to 300 °C. Thermal analysis and powder X-ray diffraction results indicated that the water molecules were removed when heated from 150 °C to 300 °C without losing the main crystal framework. Water molecules can be reassembled by exposing the dehydrated form to an atmosphere saturated with water vapor. It indicated that the dehydrated form may be utilized as a potential absorbing agent for water and water vapor. The stable dehydrated form, [MCl(phen)2][(OH)(H2O)], suggested the stronger anionic H-bonding and intracluster proton transfer process OH−·H2O → H2O·OH−. The “anion-π interaction” was found in the crystal lattice of [MCl(phen)2][(OH)(H2O)]. This paper reported an example of supramolecular polymer with open channels that could be formed/collapse reversibly upon hydration/dehydration.