This study investigates the crystalline behavior of hydrogen-bonded water molecules within the nanocages of a paddlewheel metal-organic framework (MOF), HKUST-1. Using in situ and ex situ synchrotron single-crystal X-ray diffraction (SCXRD) and Raman spectroscopy, the researchers demonstrate the vibrational chain connectivity between hydrogen bonds and the paddlewheel Cu-Cu bond. They also show the spatial ordering of hydrogen-bonded water molecules at room temperature, a state where disorder is typically expected. Furthermore, the study reveals a substantial distortion of the paddlewheel Cu²⁺ centers upon water coordination and suggests a dynamic coordination bond character for the confined hydrogen bonds.

Jinhee Bae, Sun Ho Park, Dohyun Moon, Nak Cheon Jeong