Akademik Veri Yönetim Sistemi
NEW JOURNAL OF CHEMISTRY, cilt.45, sa.45, ss.21248-21262, 2021 (SCI-Expanded)
In this study, a series of unsymmetrical 1,3-disubstituted benzimidazolium chlorides 2a-g with two nitrogen atoms substituted by different alkyl groups were synthesized in high yields as N-heterocyclic carbene (NHC) precursors. These benzimidazolium salts were then converted into the corresponding Pd-NHC complexes of the PEPPSI family (PEPPSI = pyridine-enhanced precatalyst preparation, stabilization, and initiation) 3a-g. The structures of all compounds were characterized by H-1 nuclear magnetic resonance (NMR) spectroscopy, C-13 NMR spectroscopy, infrared spectroscopy, and elemental analysis, which support the proposed structures. The structure of the 3c complex was determined by X-ray crystallography. More detailed structural characterization of the 3c complex was performed through single-crystal X-ray diffraction, which supports the proposed structures. The Pd-NHC-PEPPSI complexes were used as catalysts in the direct C-5-arylation of 2-acetyl furan, 2-acetylthiophene, and 2n-propylthiazole with different aryl bromides. These complexes exhibited moderate-to-high catalytic activities and selectively at the C-5 position. Furthermore, the Pd-NHC-PEPPSI complexes were evaluated for their potential antibacterial properties against a panel of bacterial strains, such as Micrococcus luteus, Listeria monocytogenes, Salmonella typhimurium, Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa. The Pd-NHC-PEPPSI complex 3f showed better activity than ampicillin against Micrococcus luteus, with an MIC of 0.035 mg mL(-1). In addition, the antioxidant activities of the complexes 3d and 3f showed considerable free radical scavenging activity.