418
R. Tamura et al.
Fig. 20.11 Crystal structure of (RS)-ketoprofen. a A view down the b-axis. b A view down thecaxis. See Fig. S2 for a view down the a-axis. Reproduced from Ref. [34] with permission from The
Royal Society of Chemistry
and naproxen failed to show PE due to no occurrence of polymorphic transition
during crystallization.
20.5 Second Generation of Organic Cocrystals
From the successful case of PE for the single-component ketoprofen (Sect. 20.4), we
learned that a common racemic compound with a relatively high eutectic ee value
can behave like a quasi-mixed crystal and show a good PE phenomenon by carefully
choosing nonequilibrium crystallization conditions so as to induce a desired polymorphic transition. Therefore, we focused on dimorphic cocrystals which have a high
potential of showing a polymorphism and inducing polymorphic transition during
crystallization [41]. It is anticipated that the cocrystal formation would contribute to
producing the requisite molecular arrangement in the crystal by converting a racemic