MS31-P07 POLYMORPHISM IN 2-propyl-1H-benzimidazoleBenzimidazoles, indazoles and benzotriazoles are important organic molecules very common in biological systems. Besides the role the play in these systems, they have received considerable attention in material sciences because they form materials based on these heterocycles, which exhibit notable conductivity and ferroelectric properties .
2-propyl-1H-benzimidazole (2PrBzIm, C10N2H12) , is a flexible molecule whose conformers are chiral except in the planar configuration. The compound exhibit polymorphism associated with an irreversible reconstructive-type phase transition at T= 384 K from an ordered structure I (P212121)  to a new polymorphic form IIHT (Pca21). The structural transformation between both polymorphs is interpreted by means of changes in packing and the configuration of the hydrogen bonded molecular chains. In addition, the polymorph IIHT undergoes two reversible phase transitions, at 361 K to another form IIRT with the same space group and at 180 K to a low temperature form IILT doubling one of the cell parameters. The calculation of the conformational energy landscape against the intramolecular torsion angles in 2PrBzIm allows to distinguish between changes and adjustments of the conformational configuration of the molecules in the different structures.
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 Cabildo, P., Claramunt, R. M., Zúñiga, F. J., Alkorta, I. and Elguero, J. (2015). Z. Kristallogr., 230, 427–438Keywords: 2-propyl-1H-benzimidazole, polymorphism