Imidazole Hidden PolarPhase.

Transformations of NH···N hydrogen bondscan beemployed in new classes of electronic materials. Imidazole, a prototypicNH···N bonded crystal, remains centrosymmetric whencompressed to 2.7 GPa. However, its recrystallization at 1.2 GPa leadsto a new polar phase which in turn can be decompressed to 0.5 GPaat least. This transformation and calculated potential-energy functionof the H-atom correlate with the transforming dimensions of the hydrogenbond and reveal high polarity of nonionic NH···N bondedcompounds. [ABSTRACT FROM AUTHOR]