Mechanically Flexible Crystals of Benzene Derivatives with Halogen or Methyl Groups

Abstract

The deformation of molecular crystals and their mechanical properties are of interest in materials science. Herein, the single crystals of simple benzene derivatives with bromo, iodo, and methyl substituents were prepared, and we examined the effect of the substituents on the flexibility of crystals by single-crystal structural analysis, nanoindentation test, and density functional theory (DFT) calculation. The crystals of benzene derivatives can be classified into three types: crystals that bend in one direction, crystals that bend in two directions, and crystals that do not bend, depending on the member of the halogen and methyl groups. In addition, DFT calculation also revealed the isotropic and anisotropic mechanical properties of bendable crystals.