Abstract
In recent years, symmetry-breaking has emerged as a powerful tool for significantly altering various physical properties in 2D layered materials. However, the breaking of symmetry by means of mechanical stress in organic crystals remains elusive. Here, we demonstrate a simple approach to engineer symmetry-breaking through mechanical stress fields in a layered molecular crystal, resulting in autonomous and fast self-healing under ambient temperature and pressure conditions. Fracture mechanics analysis reveals that the crystal adheres to an elasto-plastic model, with formation of a plastic zone at the crack tip, which prevents further crack propagation, facilitating the self-healing process. Spatially resolved Raman mapping reveals that the crack formation is accompanied by a distinct symmetry-breaking mechanism at the microstructural level. A six-fold increase in non-linear second harmonic (SH) activity, triggered by mechanical perturbation, further validates the local symmetry breaking in an otherwise centrosymmetric crystal. Furthermore, symmetry is restored following successful healing, as evidenced by the disappearance of the SH signal in the healed regions. This study not only broadens the scope of self-healing mechanisms viable in molecular materials but also offers key insights into the role of symmetry breaking and its potential for related technological applications.
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Data availability
The data supporting the findings of this study are available within the main text and Supplementary Information. The crystal structures have been deposited with the Cambridge Crystallographic Data Center (CCDC deposition numbers 2446102 and 2446136). Data is available from the corresponding authors upon request.
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Acknowledgements
C.M.R. thanks SERB (CRG/2021/004992) and the Swarnajayanti Fellowship (DST/SJF/CSA-02/2014-15) for funding and IISER Kolkata for instrumentation facilities. R.K. thanks the Department of Science and Technology, Govt. of India, for providing the Raman spectroscopy facility under the FIST Scheme (SR/FST/PSI-\225/2016) at IIT Indore. I.G. thanks PMRF for the fellowship. The authors wish to acknowledge Dr Mrinmay Sahu for his help with the initial Raman experiments.
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Mechanical manipulation, self-healing experiments, AFM imaging, in-situ nanoindentation, and SEM analyses were performed by I.G. R.B. performed SH generation experiments under the supervision of V.R. M.T. performed Raman spectroscopy and mapping under the supervision of R.K. SCXRD was done by K.D. and A.M. XMT imaging was done by A.T. S.B., I.G., and C.M.R. planned all the experiments; I.G. and C.M.R. analyzed the results and co-wrote the manuscript with inputs from all co-authors, and C.M.R. supervised the whole project.
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Ghosh, I., Biswas, R., Tanwar, M. et al. Fast self-healing in a layered molecular crystal mediated by stress-induced symmetry breaking. Nat Commun (2026). https://doi.org/10.1038/s41467-026-68987-z
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DOI: https://doi.org/10.1038/s41467-026-68987-z
