Subtle differences in interlayer energetics dictate facet-dependent elastic and plastic flexibility in a molecular crystal
Year: 2026
Type: preprint
Abstract: Mechanically flexible molecular crystals hold promise for emerging functional materials such as optoelectronics and piezoelectrics. Here, we report a rare example of facet-dependent elastic and plastic bending in a molecular crystal. Synchrotron micro-focused X-ray diffraction mapping (µ-XRD) and X-ray quantum crystallography (QCr) reveal distinct domain-level structural changes during plastic versus elastic deformation and variations in intermolecular interactions across the slip planes that govern these distinct mechanical responses. Potential energy densities evaluated at the interaction regions from QCr models, along with the subtle difference in interlayer binding energies (ΔE = 2.2 kJ mol-1) reveal more robust interactions that underpin the elastically bending facet. µ-XRD mapping uncovers the atomistic origin of elastic deformation in terms of molecular reorientation (Δθ = 0.38°) and packing density gradients in the bent region, whereas plastic deformation proceeds via irreversible molecular slippage, quantified by a 5-fold increase in crystal mosaicity (from 0.06° to 0.30°). These findings correlate subtle electron-density and energetic features with the domain-level changes underlying this rare phenomenon.
Source: ChemRxiv
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Funders: Arthritis National Research Foundation, Australian Nuclear Science and Technology Organisation, Australian Synchrotron, National Research Foundation, Department of Science and Technology, Ministry of Science and Technology, India, University Grants Commission, Indian Institute of Technology Delhi, Science and Engineering Research Board
OpenAlex ID: W7213252647