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    N-Heterocyclic carbene-palladium-PEPPSI complexes and their catalytic activity in the direct C-H bond activation of heteroarene derivatives with aryl bromides: synthesis, and antimicrobial and antioxidant activities
    (Royal Soc Chemistry, 2021) Hamdi, N.; Slimani, I.; Mansour, L.; Alresheedi, Faisal; Gurbuz, N.; Ozdemir, I.
    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.
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    Rhodium(I) complexes with N-heterocyclic carbene ligands: synthesis, biological properties and catalytic activity in the hydrosilylation of aromatic ketones
    (Taylor & Francis Ltd, 2021) Hamdi, Naceur; Slimani, Ichraf; Mansour, Lamjed; Alresheedi, Faisal; Ozdemir, Ismail; Gurbuz, Nevin
    New rhodium(I) N-heterocyclic carbene (NHC) complexes 3a-f were synthesized in good yields by the reactions of rhodium dimer [Rh(OMe)(cycloocta-1,5-diene:COD)](2) with benzimidazolium salts 2a-f in tetrahydrofuran. All the complexes were characterized by IR, H-1-NMR, and C-13-NMR spectroscopy, DART-TOF mass spectrometry (for 3b, 3d and 3f) and elemental analysis. All complexes were used as catalysts in the hydrosilylation of acetophenone derivatives with triethylsilane at 80 degrees C for 1 h. These Rh(I) NHC showed good catalytic performance for the hydrosilylation of acetophenone derivatives by using 1 mol % of the rhodium complexes. In addition the new rhodium(I) NHC complexes were tested against MCF7 and MDA-MB-231 cancer cells, Micrococcus luteus LB 14110, Listeria monocytogenes ATCC 19117, Salmonella Typhimurium ATCC 14028, Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa and Candida albicans microorganisms. The synthesized rhodium(I) NHC complex 3f was found the most active against MCF7 cancer cells (half-growth inhibition concentration (IC50) = 0.3 mu g mL(-1)), as well as the most potent antimicrobial against L. monocytogenes ATCC 19117 (inhibition zone (IZ) = 29 mm). Moreover, the antioxidant activity determination of these complexes was studied with the DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) and compared with gallic acid and butylated hydroxytoluene.