Influence of annealing in the close vicinity of Tg on the reorganization within dimers and its impact on the crystallization kinetics of Gemfibrozil

In this paper, Broadband dielectric spectroscopy (BDS) has been applied to study molecular dynamics and crystallization kinetics of antihyperlipidemic active pharmaceutical ingredient (API) – gemfibrozil (GEM), as well as its deuterated (dGEM) and methylated (metGEM) derivatives, characterized with different type and strength of intermolecular interactions. Moreover, calorimetric and infrared measurements have been carried out to characterize the thermal properties of examined samples as well as to probe a change in the H-bonding pattern in GEM, respectively. We found that dielectric spectra of all examined compounds, collected below the glass transition temperature (Tg), reveal the presence of two secondary relaxations (β, γ). According to the Coupling Model (CM) predictions, it was assumed that the slower process (β) is of JG-type, whereas the faster one (γ) has an intramolecular origin. Interestingly, the extensive crystallization kinetics measurements performed after applying two paths, i.e., standard...