Guest molecule dynamics and ferroelectric transition in a clathrate compound

Area of Science:

• Supramolecular chemistry
• Dielectric spectroscopy
• Ferroelectricity

Background:

• Low molecular weight glass formers in clathrate structures provide unique insights into molecular motion and ferroelectric properties.
• Understanding confined molecular dynamics is crucial for developing novel materials with specific electrical characteristics.

Purpose of the Study:

• To investigate the molecular dynamics of 1-propyl-1H-imidazole encapsulated within a p-tert-butylcalix[4]arene clathrate structure.
• To characterize the phase transition to the ferroelectric state and its relationship with molecular motion.

Main Methods:

• Broadband dielectric spectroscopy (BDS) to analyze molecular relaxations.
• Quantum chemical calculations to assign observed dynamic processes.
• Photopyroelectric calorimetry to characterize the ferroelectric phase transition.

Main Results:

• The clathrate's paraelectric phase exhibits two distinct molecular relaxation processes, unlike the bulk liquid's structural relaxation.
• The slow relaxation is attributed to head-to-tail reorientations of the guest molecule.
• The faster relaxation is linked to intramolecular fluctuations of the imidazole ring.

Conclusions:

• The study elucidates the distinct molecular dynamics of confined 1-propyl-1H-imidazole within a clathrate structure.
• Observed dynamics are directly correlated with the transition to the ferroelectric state.
• This research contributes to understanding confinement effects on molecular behavior and ferroelectricity.