A Ga‐MIL‐53‐type Framework based on 1,4‐Phenylenediacetate Showing Subtle Flexibility

The new MOF Ga‐MIL‐53‐PDA [Ga(OH)(O2C‐C8H8‐CO2)]·H2O (1) was synthesized by a hydrothermal reaction of gallium nitrate, 1,4‐phenylenediacetic acid (H2PDA) and sodium hydroxide at 100 °C for 24 h. The product is a structural analogue of the archetypical MIL‐53 framework. Its crystal structure was determined by Rietveld refinement of powder X‐ray diffraction (PXRD) data. Furthermore 1,4‐phenylenedipropionic acid (H2PDP) was employed for further synthesis, which resulted in the dense layered coordination polymers [Ga2(OH)4(O2C‐C10H12‐CO2)] (2) and [Ga(OH)(O2C‐C10H12‐CO2)] (3), for which accurate structural models could be established. All compounds were fully characterized and tested regarding potential breathing behavior. Most remarkably, Ga‐MIL‐53‐PDA showed a subtle flexibility upon de/‐rehydration also confirming its porosity, but no drastic structural changes were observed.