How Cocrystallization Affects Solid-State Tautomerism: Stanozolol Case Study

Three original cocrystals of stanozolol
with monoacidic and diacidic
coformers are presented and fully characterized in this study. Powder
X-ray diffraction (PXRD) permits cocrystal formation to be highlighted,
with the help of liquid-assisted grinding (LAG) from the two starting
coformers. Single-crystal X-ray diffraction (SCXRD) gives a detailed
structural characterization, which allows comparison with existing
structures coming from the Cambridge Structural Database (essentially
stanozolol solvates) and determination of structural similarities
between the new cocrystal structures and the existing ones. As stanozolol
can exist under two tautomeric forms (on its pyrazole moiety), statistical
and theoretical studies have been performed in order to better apprehend
the potential appearance of one of its tautomers at the cost of the
other in crystal structures, and the eventuality of “freezing”
the molecule in one of these forms by cocrystallization.