PMC

Fig. 3(A) Schematic illustration of the herein demonstrated post synthetic interconversion of (nic)·(adi) polymorphs by milling in either PMMA or ss jar. The transition enthalpy (ΔH = +2.1(3) kJ mol−1 at the transition temperature) for the metastable Form II with respect to Form I was determined by DSC. (B) Comparison of XRPD patterns for post-synthetic interconversion of (nic)·(adi) Forms I and II (top-to-bottom): Form II after 2 hours milling in a PMMA jar; Form II after 1 hour milling in a PMMA jar; as-prepared Form II; calculated XRPD pattern of Form II; Form I after 1 hour milling in a ss jar; as-prepared Form I; calculated XRPD pattern of Form I (CSD NUKYIC).

Figure 4

Figure 1

Fig. 1Schematic representation of the herein presented work, revealing that mechanochemical cocrystallisation of nic and adi can produce different, enantiotropically-related polymorphs Form I and Form II of the cocrystal (nic)·(adi), depending on the choice of the milling assembly. Similarly, milling the pre-made cocrystal polymorphs in either a PMMA or a ss milling jar enables the selective formation of either thermodynamicaly more stable Form I, or the metastable Form II, respectively. Sign for mechanochemistry (three balls) adapted from Rightmire and Hanusa.