From Mechanical Effects to Mechanochemistry: Softening and Depression of the Melting Point of Deformed Plastic Crystals

• DOI: 10.1021/jacs.0c03990
• Publication Date: 2020-05-21T23:43:52Z
• Authors: Ejaz Ahmed; Durga Prasad Karothu; Ljupčo Pejov; Patrick Commins; Qichi Hu; Panče Naumov
• Keywords: Melting-point depression; Crystal (programming language); Endothermic process

The melting of any pure crystalline material at constant pressure is one its most fundamental properties, and it has been used to identify organic compounds or verify their chemical phase purity since the early times chemistry. Here, we report that a mechanical deformation plastic single crystals such as bending results in small yet significant decrease point about 0.3–0.4 K. bent section crystal was found be mechanically softer relative straight sections, softening temperature preceding also lower on convex (outer) side crystal. Melting starts kink often appears splitting respective endothermic peak thermal (DSC) fingerprint, while unilateral compression multiple peaks. These thermomechanical effects become more pronounced with heavier damage due an increased concentration defects ultimately result large spread associated change addition melting-point depression deformed damaged pristine counterparts. Within broader context, show treatment during sample preparation profound effect substance, this could critically important where exact means for polymorph identification.