Mechanical properties of molecular crystals

Nanoindentation is an effective method to assess the mechanical response of solids with high precision, and on extremely small volumes. It provides useful information on the mechanical properties of polymorphic drugs, which in turn allows for developing an understanding of their stability in the solid state. We use nanoindentation and nanoscratching as tools to study mechanical anisotropy, interaction characteristics, desolvation processes, polymorphism, phase stability, and molecular migration in molecular crystals. It may be used as a direct measure of molecular and crystal energies of molecular crystals. In all these studies we try to understand these phenomena as a function of crystal packing. As in all types of crystal engineering, an understanding of the intermolecular interactions can lead to property oriented crystal design, and we have shown that complex properties may be deliberately turned on or off in organic crystals: one essentially fine-tunes the degree of isotropy/anisotropy by modulating interactions such as hydrogen bonding, halogen bonding, π···π interactions, and C−H···π interactions.


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