Abstract:
Organic crystals possessing elasticity are gaining wide attention due to their potential
applications in technology. From a design perspective, it is of utmost importance to understand
the mechanical behavior of these crystals and their ability to handle stress. In this paper, we
present an in situ high-pressure Fourier transform infrared spectroscopy study on 2,5-dichloroN-benzylidene-4-chloroaniline (DPA) and 2,6 dichloro-N-benzylidene-4-fluoro-3-nitro aniline
(DFA) crystals at pressures ranging from ambient pressure to 21.5 and 14.5 GPa respectively
along with nanoindentation studies, at room temperature. The infrared stretching wavenumber
of the aromatic and aliphatic C–H, H–C═N, and C–Cl bands on compression showed blueshifts
and increased widths, which reflect structure perturbation caused by changes in intermolecular
interactions in the crystals. It was noted that both crystals DPA and DFA behave in a different
fashion under high-pressure prompting the derivation of different models based on structural
changes in the lattice. Further, nanoindentation studies corroborated pressure-induced
molecular movement in both crystals.
