Quantifying the Structural Dynamics of Pharmaceuticals in the Glassy State

Area of Science:

• Materials Science
• Physical Chemistry
• Condensed Matter Physics

Background:

• Protic ionic liquids (PILs) exhibit complex dynamics in their glassy state.
• Understanding structural dynamics is crucial for predicting material properties and stability.
• Physical aging significantly influences the relaxation behavior of amorphous materials.

Purpose of the Study:

• To characterize the structural dynamics of carvedilol phosphate and procaine hydrochloride in the glassy state.
• To investigate the impact of physical aging on conductivity relaxation times.
• To explore the relationship between relaxation times and heterogeneous dynamics in supercooled PILs.

Main Methods:

• Analysis of conductivity relaxation times during physical aging.
• Comparison of obtained relaxation times with published data from secondary relaxation methods.
• Observation of relaxation dispersion narrowing at higher frequencies.

Main Results:

• Extremely long relaxation times, beyond experimental reach, were inferred from conductivity data.
• The inferred relaxation times are consistent with values obtained through secondary relaxation analysis.
• A narrowing of the relaxation dispersion was observed at higher frequencies, indicative of heterogeneous dynamics.

Conclusions:

• Physical aging profoundly affects the structural dynamics of PILs.
• The study provides insights into the slow dynamics and heterogeneity in glassy ionic liquids.
• The findings contribute to a deeper understanding of relaxation processes in supercooled amorphous materials.