The impact of chemical structure on the formation of the medium-range order and dynamical properties of selected antifungal APIs

Design of a homologous series of molecular glassformers

We design and synthesize a set of homologous organic molecules by taking advantage of facile and tailorable Suzuki cross coupling reactions to produce triarylbenzene derivatives. By adjusting the number and the arrangement of conjugated rings, the identity of heteroatoms, lengths of fluorinated alkyl chains, and other interaction parameters, we create a library of glassformers with a wide range of properties. Measurements of the glass transition temperature (T_g) show a power-law relationship between T_g and molecular weight (M_W), with of the molecules, with an exponent of 0.3 ± 0.1, for T_g values spanning a range of 300-450 K. The trends in indices of refraction and expansion coefficients indicate a general increase in the glass density with M_W, consistent with the trends observed in T_g variations. A notable exception to these trends was observed with the addition of alkyl and fluorinated alkyl groups, which significantly reduced T_g and increased the dynamical fragility (which is otherwise insensitive to M_W). This is an indication of reduced density and increased packing frustrations in these systems, which is also corroborated by the observations of the decreasing index of refraction with increasing length of these groups. These data were used to launch a new database for glassforming materials, glass.apps.sas.upenn.edu.

Influence of High Pressure on the Local Order and Dynamical Properties of the Selected Azole Antifungals

Dielectric studies under various temperature (T) and pressure (p) conditions on five active pharmaceutical ingredients (APIs) with antifungal properties-itraconazole (ITZ), posaconazole (POS), terconazole (TER), ketoconazole (KET), and fluconazole (FLU)-were carried out. We have thoroughly studied the connection between the pressure coefficient of the glass transition temperature (dT_g/dp) and the activation volume of both relaxation modes (ΔV_α, ΔV_δ/α') with respect to the molecular weight (M_w) or molar volume (V_m) in these systems. Besides, high pressure data revealed that the time scale separation between α- and δ- or α'-processes increases with pressure in ITZ and TER. What is more, the activation entropy, which is a measure of cooperativity, calculated from the Eyring model for the secondary (β)-relaxation in ITZ and POS, increased and decreased, respectively, in the compressed samples. To understand these peculiar results, we have carried out X-ray diffraction (XRD) measurements on the pressure-densified glasses and found that pressure may induce frustration in molecular organization and destroy the medium-range order while enhancing the short-range correlations between molecules. This finding allowed us to conclude that varying molecular spatial arrangement is responsible for the extraordinary dynamical behavior of ITZ, POS, and TER at high pressure.