Co-precipitation is an emerging method to generate amorphous solid dispersions (ASDs), notable for its ability to enable the production of ASDs containing pharmaceuticals with thermal instability and limited solubility. As is true for spray drying and other unit operations to generate amorphous materials, changes in processing conditions during co-precipitation, such as solvent selection, can have a significant impact on the molecular and bulk powder properties of co-precipitated amorphous dispersions (cPAD). Using posaconazole as a model API, this work investigates how solvent selection can be leveraged to mitigate crystallization and maximize bulk density for precipitated amorphous dispersions. A precipitation process is developed to generate high-bulk-density amorphous dispersions. Insights from this system provide a mechanistic rationale to control the solid-state and bulk powder properties of amorphous dispersions.

The pure rotational transitions of ${\text{H}}_2\text{–AuCl}$ have been measured using a pulsed-jet cavity Fourier transform microwave spectrometer equipped with a laser ablation source. The structure was found to be T-shaped, with the H–H bond interacting with the gold atom. Both ³⁵Cl and ³⁷Cl isotopologues have been measured for both ortho and para states of H₂. Rotational constants, quartic centrifugal distortion constants, and nuclear quadrupole coupling constants for gold and chlorine have been determined. The use of the nuclear spin-nuclear spin interaction terms D_aa, D_bb, and D_cc for ${\text{H}}_2$ were required to fit the ortho state of hydrogen, as well as a nuclear-spin rotation constant C_aa. The values of the nuclear quadrupole coupling constant of gold are ${\chi }_{aa}=-817.9929(35)$ MHz, ${\chi }_{bb}=504.0(27)$ MHz, and ${\chi }_{cc}=314.0(27)$ . This is large compared to the eQq of AuCl, 9.63 312(13) MHz, which indicates a strong, covalent interaction between gold and dihydrogen.