Next, we explored the possibility of polymorph interconversion under mechanochemical conditions. We performed NG of polymorph α at room temperature. However, the transition to high-temperature polymorph β did not occur after milling at 30 Hz for 1 h (ESI Fig. ). Moreover, α→β transition did not occur even after LAG of polymorph α with THF, the same solvent from which single crystals of polymorph β were grown, at room temperature for 1 h (ESI Fig. ). On the other hand, LAG of polymorph β with npentane resulted in a transition to room-temperature polymorph α after 45 min of milling at ambient conditions (ESI Fig. ). Notably, NG of polymorph β at room temperature for 24 h resulted in a mixture of polymorphs (ESI Fig. ), consistent with polymorph β being metastable at room temperature.