The role of dimensionality and direction of hydrogen-bonded networks in the mechanical flexibility of organic crystals

Abstract

The role of directionality and dimensionality of hydrogen-bonded networks in the flexibility of organic crystals has been discussed in this highlight. Only those flexible organic crystals whose hydrogen-bonded networks are 1D, 2D, or 3D in their crystal structures have been considered and only conventional strong hydrogen bonds such as O–H⋯O, O–H⋯N, N–H⋯O, N–H⋯N, etc. are considered. 37 cases of plastic/elastic bending and one case of shearing crystals have been analyzed. How the crystal grows with respect to the unit cell dimension and the hydrogen-bonded networks has also been taken into account in this analysis. As hydrogen-bonded synthons are the main and most reliable element in crystal engineering while designing molecules to obtain crystals with desired properties, we anticipate that this knowledge, discussed here, would be helpful in designing flexible crystals with desired properties.