Mechanistic Insights into Mechanically Flexible Molecular Crystals: from Design to Synthesis

• Applicant: Dr. Biswajit Bhattacharya
• Subject Area: Solid State and Surface Chemistry, Material Synthesis ; Synthesis and Properties of Functional Materials
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 450137475

Molecular crystals are in general mechanically weak and susceptible to breakage under an applied stress. The phenomenon of mechanical flexibility in molecular materials has been known for at least two decades and has roused considerable excitement surrounding their potential technological application, such as in smart optoelectronics, biomedical and bioengineering devices, and pharmaceuticals. However, with only a handful of reported flexible materials, and only speculative models, mechanical flexibility in molecular materials remains poorly understood. Until a concrete understanding of the structure-properties relationship of these remarkable materials is obtained their full potential in next generation technologies cannot be realised. A complete study of molecular mechanisms for this process is essential to exploit the physical properties of the molecular crystals that exhibit mechanical flexibility. This can only be achieved through systematic investigation of structure and property relationship in mechanically flexible crystals. The central aim of this proposal is to identify the origin of mechanical flexibility at the molecular level in molecular crystals. This will be achieved by systematically investigating the evolution of the (crystal) structure as a result of mechanical bending using a combination of advanced experimental techniques. Advanced structural characterization will include state-of-the-art techniques likesynchrotron-basedd micro-focussingle-crystall X-ray diffraction, micro-FTIR, micro-Raman scattering, and nanoindentation. These techniques will probe the pre- and post-bent crystal states of newly synthesized flexible molecular crystals, providing novel insight into the effects of crystal bending on molecular structure. The successful execution of this project will provide unprecedented insight into the mechanisms of these materials, thereby facilitating rational approaches to designing mechanically responsive functional single crystals. This will vastly improve our capability in the fast-emerging field of stimuli responsive smart single crystals for utilizing them in next generation devices.

• DFG Programme: Research Grants