Studies on the internal medium-range ordering and high pressure dynamics in modified ibuprofens

Area of Science:

• Materials Science
• Physical Chemistry
• Pharmaceutical Science

Background:

• Ibuprofen (IBU) derivatives are widely used pharmaceuticals.
• Understanding their molecular dynamics and structural properties is crucial for drug development.
• Previous studies have explored relaxation processes in similar compounds.

Purpose of the Study:

• To investigate the dynamics of primary (α) relaxation and slow mode (SM) in ibuprofen esters.
• To analyze structural properties and intermolecular interactions using multiple spectroscopic techniques.
• To explore the effect of high pressure on molecular dynamics and relaxation processes.

Main Methods:

• Broadband dielectric spectroscopy (BDS) for dynamic analysis.
• X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy for structural characterization.
• High-pressure dielectric experiments to probe pressure-dependent dynamics.

Main Results:

• Formation of medium-range ordering and small aggregates (microns) observed at lower temperatures.
• Slow mode (SM) relaxation was not detected under high pressure in ibuprofen esters.
• Non-monotonic changes in the pressure coefficient of glass transition temperature (dTg/dp) and activation volume (ΔV) with molecular weight (Mw).

Conclusions:

• Ibuprofen esters exhibit complex structural organization and aggregation.
• High pressure significantly influences or suppresses slow mode dynamics.
• The observed non-monotonic behavior in thermodynamic parameters suggests intricate structure-property relationships influenced by molecular weight and intermolecular forces.