Two conformational polymorphs of 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile (ROY) exhibited similar morphology but strikingly different mechanical flexibility, where the yellow needle (YN) is exceptionally elastic while orange needle (ON) is highly brittle. Similar to color differentiation, the distinct bending behaviors of YN and ON polymorphs are linked to different molecular conformations. Aided by crystal structural analysis, interaction energies, topology, nanoindentation, and elastic constant calculation, this study reveals new structural insights that explain the strikingly different mechanical behaviors of the two polymorphs.
Bibliographical noteFunding Information:
The authors acknowledge the Minnesota Supercomputing Institute (MSI) at the University of Minnesota for providing resources that contributed to the research results reported within this paper. The single-crystal diffraction experiments were conducted at Department of Chemistry, University of Minnesota. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. The videos were captured using a higher speed camera at the Minnesota Dental Research Center for Biomaterials and Biomechanics (MDRCBB).
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