Structural phase transitions of N2-loaded and guest-free hydroquinone (HQ) clathrates have been investigated as a function of pressure using synchrotron X-ray diffraction and Raman spectroscopy. The N 2-loaded β-form HQ clathrate reveals a structural transition to a new high pressure phase near 4 GPa and exhibits gradual N2 release from the hydrogen-bonded organic framework (HOF) cage with a further increase in pressure. Upon reducing the pressure to ambient conditions, the crystal structure reverts to the original β-form HQ clathrate, indicating that the pressure-induced structural transition is fully reversible. In contrast, around 0.4 GPa, the guest-free β-form HQ clathrate undergoes an irreversible phase transition to the nonporous α-form HQ, which is retained at ambient conditions. These results suggest that HOF encaged guest molecules play an important role in the structural transitions under high pressure.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry