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    Complexes formed by a heterocyclic schiff base containing an aminothiophene group with Ni(II) and Co(II) metals and their structural characterization
    (Elsevier, 2026) Yavuz, Senol; Colak, Naki; Yildirim, Tugrul; Kose, Dursun Ali; Sahin, Onur
    In this study, compound 2, a novel Schiff base ligand containing an aminothiophene group, was synthesized and thoroughly characterized. The amine precursor (1) was condensed with 5-chloro-2-hydroxybenzaldehyde to yield the target ligand in high yield (90%). The ligand's structure was confirmed using FT-IR, 1H NMR, 13C-APT NMR, LC-MS (-ESI), and elemental analysis. The crystallographic study revealed that the ligand is arranged in the triclinic P & imath; space group, with two molecules present in each unit cell. The measured C7-N1 and C10-O2 bond lengths exhibit double-bond character, and the phenyl-thiophene dihedral angle of 6.02 degrees points to an almost planar structure. A hydrogen bond formed within the molecule between the phenolic-OH and imine nitrogen, and pi & sdot;& sdot;& sdot;pi interactions between adjacent molecules enhanced crystal stability. The ligand reacted with Co2+ and Ni2+ salts under reflux conditions to afford the corresponding metal complexes (3 and 4). Analysis by FT-IR revealed that the phenolic-OH band vanished, while the C = O and imine (C = N) groups participated in coordination. The imine stretching shift indicated nitrogen coordination, and the additional bands in the 655-531 cm-1 region verified metal-oxygen interactions. Elemental analyses matched the proposed molecular formulas, and magnetic susceptibility measurements indicated octahedral Co2+ and Ni2+ centres with paramagnetic properties. Thermal analyses revealed a multi-step decomposition process, ultimately yielding metal oxides (CoO, NiO) as the final residues. This study demonstrates that the Schiff base ligand acts as a bidentate (O, N) chelating agent, forming stable metal complexes. The ligand and its complexes, due to the imine group, thiophene ring, and heterocyclic structure, offer potential antimicrobial, anticancer, antioxidant, and sensor applications. These results underscore the role of Schiff bases and transition metal complexes in catalysis, materials science, and bioinorganic applications.
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    Öğe
    Synthesis and characterization of 4-hydroxy-3-((2-hydroxy-3-methoxyben-zylidene)amino)benzene-sulfonic acid and its metal complexes and their antimicrobial activity
    (Elsevier, 2025) Yavuz, Senol; Kose, Dursun Ali; Ozkinali, Sevil; Tatar, Demet; Veyisoglu, Aysel
    Schiff base was obtained from the reaction of vanillin with 3-amino-4-hydroxybenzenesulfonic acid. Metal complexes were synthesized using (Ni(NO3)2, Co(NO3)2, Mn(NO3)2, Cu(NO3)2, Zn(NO3)2) metal salts and the structures of the compounds were elucidated by spectroscopic methods. The structures of the metal complexes were also characterized by elemental analysis, FT-IR, thermogravimetric analysis and magnetic susceptibility analysis and their antimicrobial activities were investigated. The antimicrobial activities of the obtained coordination compounds were investigated against three Gram-positive (Bacillus subtilis ATCC 6633; Staphylococcus aureus ATCC 25923; Enterococcus faecalis ATCC 29212) three Gram-negative bacterial (Escherichia coli ATCC 25922; Klebsiella pneumonia ATCC 70060; Pseudomonas aeruginosa ATCC 27853) strains and two fungal (Aspergillus niger ATCC 16404; Candida albicans ATCC 1023) strains, and the minimum inhibitory concentration (MIC) values were determined. According to the MIC values, the SC-Ni complex exhibited the highest antimicrobial activity, while the SC-Cu complex showed the lowest.