Prestige 21 infrared spectrophotometer

PXRD was performed on a power X-ray diffractometer (D2 Phaser, Bruker Co., Bremen, Germany) using a Cu-Kα source at 30 kV and 10 mA. The PXRD pattern was collected from 5° to 40° (2θ) at ambient temperature with a step size of 0.05°(2θ) and time per step of 0.3 s. DSC analysis was performed on a DSC 214 apparatus (NETZSCH Company, Selb, Germany). Approximately 3–5 mg of sample was accurately weighed and placed in an aluminum pan. The sample pan was heated from 20 to 400 °C at a rate of 5 °C∙min⁻¹ under a nitrogen purge of 50 mL∙min⁻¹. The empty aluminum pan was used as a reference. The SEM system (Hitachi S-4800, Tokyo, Japan) was used to observe the morphologies of GA, CCFs and the cocrystals. By dropping the ethanol suspension of the sample onto the electric glass slice, the precipitate on the glass slice was observed after the solvent volatilized. The FTIR spectra were recorded on a Prestige-21 infrared spectrophotometer (Shimadzu, Japan) using the KBr pellet method. The scan range was set from 400 to 4000 cm⁻¹ at 2 cm⁻¹ resolution. The ¹H NMR spectra were recorded on a WIPM 400 MHz NMR spectrometer (Zhongke-Niujin, Wuhan, China) at a temperature of 293.1 K. Samples were prepared by dissolving about 5 mg of sample in 500 μL of D₂O. The spectral width was set as 11,013 Hz. The cumulative number of times was 16, and the relaxation time D₁ was 1 s.