Thermal treatment induced transition from Zn3(OH)2(BDC)2 (MOF-69c) to Zn4O(BDC)3 (MOF-5)

A simple thermal treatment induced transition from Zn-3(OH)(2)(BDC)(2) (MOF-69c) to Zn4O(BDC)(3) (MOF-5) is reported. Phase crystallinity, pore characteristics and hydrogen storage capacities of the resulting crystals were investigated. It is shown that the structural transition from Zn-3(OH)(2)(BDC)(2) (MOF-69c) to Zn4O(BDC)(3) (MOF-5) could be induced by simply employing the optimal thermal treatment conditions of 200 degrees C for 48 h in open air. The resultant relatively lower specific surface area of MOF-5 crystals compared to MOF-69c was in agreement with the increased pore diameter and decreased hydrogen storage capacity at 1 bar and 77 K.