Fourier transform infrared ftir spectrophotometer

All reagents and solvents were purchased from Sigma-Aldrich (Singapore) and Merck (Germany). The synthesis reactions were evaluated by thin-layer chromatography using silica gel (F254 plate; Merck, Singapore). Melting points were determined in open capillaries using an electrothermal IA 9200 melting point apparatus. Proton nuclear magnetic resonance (¹H-NMR) spectra were obtained from NMR Jeol ECS 400 MHz spectrometer (USA) using deuterated chloroform (CDCl₃) as a solvent and tetramethylsilane as an internal standard. Mass spectra were detected on Agilent 1260 Infinity high-performance liquid chromatography (HPLC) and Agilent 6530 Accurate-Mass Q-TOF/MS (USA). Infrared spectra (KBr disk) were recorded with an 8400S/Shimadzu Fourier transform infrared (FT-IR) spectrophotometer (Japan). All microorganisms in the antibacterial assay were obtained from the Microbiology Laboratory of RSUD, Dr. Saiful Anwar Hospital (Indonesia). Mannitol salt agar, Mueller-Hinton agar, Mueller-Hinton broth, and nutrient broth were purchased from Merck (Germany). Standard antibacterial drugs such as vancomycin (Fahrenheit, Indonesia), ciprofloxacin (Hexpharm Jaya, Indonesia), and gentamicin (Indofarma, Indonesia) were used for comparison.