A Novel System for Crystal Polymorph Discovery via Selective-Wavelength Infrared Irradiation Using Metamaterials

The control of crystal polymorphs is central to the design of pharmaceuticals and functional materials. Conventionally, crystal polymorph production has been controlled primarily by adjusting chemical and thermodynamic parameters. In this study, we developed a device capable of emitting infrared radiation at selected wavelengths using a novel material having a “MIM structure” which is a type of metamaterial. With this device, we propose a new approach to crystal polymorph control through the irradiation of narrow-band infrared radiation that coincides with the infrared absorption band of specific functional groups. In this paper, we present the design and operating principle of a new crystallization system, and as an application example, we report the experimental results of controlling the crystal polymorphs of Ritonavir, an active pharmaceutical ingredient.