High-Pressure Polymorphism in Hydrogen-Bonded Crystals: A Concise Review

Abstract

High-pressure polymorphism is a developing interdisciplinary field. Pressure up to 20 GPa is a powerful thermodynamic parameter for the study and fabrication of hydrogen-bonded polymorphic systems. This review describes how pressure can be used to explore polymorphism and surveys the reports on examples of compounds that our group has studied at high pressures. Such studies have provided insight into the nature of structure–property relationships, which will enable crystal engineering to design crystals with desired architectures through hydrogen-bonded networks. Experimental methods are also briefly surveyed, along with two methods that have proven to be very helpful in the analysis of high-pressure polymorphs, namely, the ab initio pseudopotential plane–wave density functional method and using Hirshfeld surfaces to construct a graphical overview of intermolecular interactions.

High Pressure Study of Pharmaceutical and Energetic Material Hexamethylenetetramine

“…Pressure on a tens of gigapascals scale can induce significant variations in relatively weak interactions and can be harnessed as a potent tool to reveal concealed phenomena that exist under ambient pressure conditions. − High pressure has been extensively employed to investigate a diverse array of materials, encompassing metals, semiconductors, superconductors, minerals, and ice. − Pressure can effectively elevate the critical temperature for superconductivity. , The pressure-induced emission behavior exhibited by perovskites holds potential applications in pressure sensing. − Two distinct categories of materials, pharmaceutical compounds and energetic materials, have garnered escalating scientific attention. − In the production of pharmaceuticals, the manufacturing process involves various procedures such as crystallization, milling, freeze-drying, and tabletting. During these processing and formulation stages, pharmaceutical compounds are frequently subjected to pressure, leading to interconversions between solid forms that can impact properties such as efficacy and toxicity. , Hence, the study of pressure plays a pivotal role in the pharmaceutical industry.…”