Preparation, characterization, and in vitro antibacterial activity of Cu(II)-pyrazinamide complexes,
Authors: Karti'a Galuh Wahyu , Purwonugroho Danar , Srihardyastutie Arie , Prananto Yuniar Ponco 
Published: October 2024

<p>Transition metal complexes, including <em>copper(II) complexes</em>, are being investigated as potential next-generation antibacterial agents. This study aims to prepare several <em>Cu(II)-pyrazinamide</em> (<em>Cu(II)-pza</em>) complexes using <em>Cu(II)</em> salts (acetate, chloride, nitrate, sulphate) through a direct mixing technique. Different <em>Cu(II)</em> salts are anticipated to yield distinct complexes, resulting in varied antibacterial properties. The <em>Cu(II)-pza</em> complexes were characterized using melting point analysis, infrared spectroscopy, and powder X-ray diffraction (XRD). Melting point analysis provides insights into the physical properties of the complexes. Infrared spectroscopy identifies functional groups and predicts chemical bonds within the complexes. Powder XRD analyzes the characteristic diffraction patterns of the complexes. Experimental data reveal that the infrared spectra of all <em>Cu(II)-pza</em> complexes exhibit typical absorption bands of the pyrazinamide ligand (N-H, C=O, C-N, and C=N). Powder XRD analysis shows different diffraction patterns for each complex, indicating the formation of different compounds due to variations in anion and metal-ligand interactions, with the sulphate complex matching a previously reported complex. Melting point tests indicate the decomposition of the complexes within the range of 215–225 °C, except for the acetate complex, which decomposes at 275 °C. The antibacterial activities of these complexes against <em>S. aureus</em> and <em>E. coli</em> were examined in vitro based on inhibition zone diameter and MIC value. The sulphate, nitrate, and chloride complexes exhibit MIC values of 1,000 ppm and MBC values of 6,000 ppm, demonstrating better antibacterial activity against <em>S. aureus</em> than <em>E. coli</em>. 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