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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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    Novel coordination compounds: Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) cations with acesulfame/N,N-diethylnicotinamide ligands
    (Taylor & Francis Ltd, 2019) Yildirim, Tugrul; Kose, Dursun Ali; Avci, Guelcin Alp; Sahin, Onur; Akkurt, Fatih
    Five coordination complexes with Mn2+ (1), Co2+ (2), Ni2+ (3), Cu2+ (4), and Zn2+ (5) containing acesulfame (ace) and N,N-diethylnicotinamide (dena) ligands were synthesized and structural binding properties investigated. Four compounds (1, 2, 4, and 5) were examined with single crystal X-ray diffraction methods. The structures containing Mn(II), Co(II), and Zn(II) were iso-structural. Six-coordination of metal cations were completed with two moles dena and four aqua ligands. The dena ligands were coordinated via pyridine nitrogen as neutral-monodentate. Charge stabilities of the complexes are complemented by two moles monoanionic ace ligands, located outside of the coordination unit. In the Cu(II) complex, the coordination is completed by acidic nitrogen and carbonyl oxygen atoms of two ace ligands and pyridine nitrogen of two moles dena ligands. The coordination to Cu(II) for ace ligands was monoanionic-bidentate. All metal cations in the structure are distorted octahedral. Thermal decomposition of complexes begins with removal of the aqua molecules from the structures and is completed by combustion of organic ligands. The final decomposition products of all structures have been identified as corresponding metal oxides. Some biological applications (anti-fungal/anti-bacterial) were studied using 1-5.
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    Novel mixed ligand complexes of acesulfame / nicotinamide with some transition metals. Synthesis, crystal structural characterization, and biological properties
    (Elsevier Science Bv, 2019) Yildirim, Tugrul; Kose, Dursun Ali; Avci, Emre; Ozer, Demet; Sahin, Onur
    The salt type mixed ligand metal complexes of COII (I), Ni-II (II), Cu-II (III), Zn-II (IV) and Mn-II (V) were synthesized using neutral ligand nicotinamide and anionic ligand acesulfame. The structural characterizations of complexes were performed by using elemental analysis, magnetic susceptibility, solid-state UV-Vis, FUR spectra, thermoanalytic TG-DTG/DTA, and single crystal X-ray diffraction methods. The complexes of I, III, IV, and V were obtained suitable crystal form for single crystal analysis by SC-XRD diffraction. The complexes of II was believed that the others structures so, the spectroscopic results of all the complexes are suitable for each other. The complexes are salt type compounds, and they have 2 mol nicotinamide ligands as monodentate coordination to metal center by pyridine N atoms and 4 mol aqua ligands in coordination sphere and 2 mol anionic acesulfamate ligands located outside of coordination unit as a counter ion. The metal(II) cationic atoms in complexes have octahedral geometry. Thermal decomposition steps of compounds are started with dehydration. (C) 2018 Published by Elsevier B.V.
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    Novel mixed ligand complexes of Co(II), Ni(II), Cu(II), and Zn(II) with 1,10-phenanthroline and acesulfame. Synthesis, structural analysis and hydrogen adsorption study
    (Pergamon-Elsevier Science Ltd, 2021) Sahin, Zarife Sibel; Demir, Mehmet; Yildirim, Tugrul; Yurdakul, Omer; Ali Kose, Dursun
    Four novel metal organic framework (MOF) structures containing acesulfame (ace) and 1,10-phenanthroline (phen) ligands of Co2+, Ni2+, Cu2+ and Zn2+ metal cations were synthesized. The crystal structure analysis of three compounds (1, 2, and 3) was also performed. The structural formula for complex 4 is proposed based on spectroscopic and thermal analysis data. It has been determined that structures 1, 2, and 4 are in a distorted octahedral geometry. It has been suggested that the charge balance of the coordination sphere with 2+ is provided by two monoanionic ace ligands located outside the coordination sphere as counter-ion. In structure 3, there are two Cu-II metal cations, two phen ligands coordinated as bidentate to each metal cation and ace ligand that provides monoanionic-monodentate coordination. The Cu2+ cation has distorted bipyramidal geometry. The maximum hydrogen gas adsorption has been found 1.4575 mL/g (0.046 wt%) for the Ni complex. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.