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    A Crystallographic, EPR and DFT Investigations of a Novel Magnetically Silent Mono-atom Acetate-Bridged Binuclear Schiff Base-Copper(II) Complex
    (2017) Demir, Serkan; Yerli, Yusuf; Öztürk, Mustafa; Saral, Hasan; Temel, Ersin; Başgel, Serkan
    A recent example of one-atom acetate bridged symmetric dinuclear copper(II) complexes, Di-µ-acetato-bis{1- ((pyridin-2-ylmethylimino)methyl)naphthoxo}copper(II) ([Cu2(NP)2(Ac)2]•2MetOH(1)) (HNP=1-((pyridin-2- ylmethylimino)methyl)naphthol)) have been prepared and characterized by X-ray crystallography, Elemental analyses, ESI-mass, UV-Vis and IR spectroscopic techniques. Magnetic properties of the complex have been probed by EPR measurements and the presence of spin-only paramagnetism of the compound with none of significant exchange coupling has been demonstrated unlike ferro or antiferromagnetism that was otherwise observed in all other analogous structures previously reported. The existence of a trivial ferromagnetic exchange which is quantitatively ignorable has been suggested by DFT-Broken Symmetry calculations performed at crystallographically characterized experimental geometry.
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    Öğe
    A disparate 3-D silver(I) coordination polymer of pyridine-3,5-dicarboxylate and pyrimidine with strong intermetallic interactions: X-ray crystallography, photoluminescence and antimicrobial activity
    (Taylor & Francis Ltd, 2015) Alisir, Sevim Hamamci; Demir, Serkan; Sariboga, Bahtiyar; Buyukgungor, Orhan
    A polymeric silver(I) complex, [Ag-4(-pydc)(2)(-pm)(2)](n) (1) (pydc=pyridine-3,5-dicarboxylate and pm=pyrimidine), has been synthesized and characterized by elemental analysis, IR spectroscopy, thermal analysis, and single-crystal X-ray diffraction. X-ray crystallographic data of 1 revealed that pydc exhibits two different coordinaton modes that play a key role in the construction of the 3-D crystal network including Ag-carboxylate clusters in which close Ag-Ag distances exist. The magnitudes of close Ag-Ag interactions in second-order energy (E-2) have been revealed by natural bond orbital analysis performed with single point energy calculation using the experimental geometry of 1. Furthermore, the luminescent properties of 1 show strong fluorescence with two emission maxima in the visible region. Also, 1 has antifungal activity on Candida albicans (MIC value, 4gmL(-1)) and good antibacterial activity on micro-organisms (MIC value, 64-256gmL(-1)).
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    Öğe
    Cobalt(III) complex of substituted nalidixic acid: Synthesis, characterization (IR, UV, EPR), single crystal X-ray, antimicrobial activity, Hirshfeld surface analysis and molecular docking
    (Elsevier, 2021) Aycan, Tugba; Ozturk, Filiz; Demir, Serkan; Ozdemir, Nilgun; Pasaoglu, Humeyra
    The mixed-ligand title complex, [Co(nal)(2)(py)(2)]center dot 4H(2)O (Hnal=nalidixic acid, py=pyridine), was synthesized. Its structural properties were characterized by X-ray diffraction technique (XRD) and elemental analysis. The spectroscopic properties are investigated by Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy and EPR spectroscopy. The Co(II) ion has slightly distorted octahedral geometry surrounded by two oxygen atoms of keto and carboxyl groups bonded as chelate from nalidixate, two nitrogen atoms from two pyridine ligands. The monomer are connected by C-H center dot center dot center dot O and C-H center dot center dot center dot C interactions to form sheet structures. The FT-IR studies of the complex were commented, focusing on the shifts in the vibrational peaks between the complex form and free nalidixic acid. The powder EPR spectra of Cu(II)-doped complex were investigated at room and at liquid nitrogen temperature. The EPR and UV-Vis spectroscopy studies showed that the unpaired electrons were found in the d(x2-y2) orbitals by calculating the spin-Hamiltonian and bond parameters. 2D and 3D Hirshfeld analyses were performed in order to quantify the order and nature of intermolecular interactions in crystal network. Antibacterial activity of complex was studied against S. aureus, B. subtilis, P. aeruginosa, E. coli, C. albicans and A. flavus by using the micro dilution. The optimized complex is docked to 5J9B (S. aerous), 5BMM (E. Coli), 5HTG (C. Albicans), 1ZUV (B. Subtilis), 4F0V (P. aeruginosa) and 4YNU (A. flavus). (c) 2020 Elsevier B.V. All rights reserved.
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    Synthesis, spectroscopic, molecular and computational structure characterizations of (E)-2-ethoxy-6-[(phenylimino)methyl]phenol
    (Elsevier, 2010) Albayrak, Cigdem; Kosar, Basak; Demir, Serkan; Odabasoglu, Mustafa; Buyukgungor, Orhan
    The structure of (E)-2-ethoxy-6-[(phenylimino)methyl]phenol was characterized by X-ray diffraction, IR and electronic spectroscopy. The title compound prefers enol form in solid state as to X-ray and IR results. UV-Vis spectra of the title compound were recorded in various solvents. The results show that the molecule exists only enol form even in solvent media. Electronic structure and spectroscopic properties of title compound were investigated from calculative point of view. DFT/B3LYP optimization was performed based on X-ray Geometry applying 6-311 G(d,p) basis set. TD-DFT calculations starting from optimized geometry were carried out in both gas and solution phase to calculate excitation energies of enol and keto tautomers. Vibrational frequency analysis was performed at the optimized geometry with the same level of theory. (c) 2009 Elsevier B.V. All rights reserved.
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    Öğe
    Synthesis, structural, spectral and antimicrobial activity studies of copper-nalidixic acid complex with 1,10-phenanthroline: DFT and molecular docking
    (Pergamon-Elsevier Science Ltd, 2020) Aycan, Tugba; Ozturk, Filiz; Doruk, Tugrul; Demir, Serkan; Fidan, Melek; Padaoglu, Humeyra
    The mix-ligand coordination compound, [Cu(Nal)(Phen)(H2O)]center dot(Phen)center dot ClO4 center dot(H2O)(2) (Nal= Monoanion of nalidixic acid and Phen = 1,10Phenanthroline), was investigated by focusing on its supramolecular architecture. Structural properties of the complex were characterized by XRD, spectroscopic methods and elemental analysis. The complex has crystallized in the triclinic crystal system and P-1 space group. In the structure where the Cu (II) ion is in the center of symmetry, nalidixate anion and water molecule coordinated to Cu (II) metal through oxygen atoms while phen coordinated through nitrogen atoms. The monomer units are connected by hydrogen bonds to form supramolecular structures. The ground state molecular structure of the complex was optimized using DFT/B3LYP/LANL2DZ method, and compared with experimental X-ray geometry. The FT-IR study of the complex was carried out in the middle IR region focusing on the characteristic vibrations of the free ligands and the complex. Scaled calculated vibrational frequencies are compared with experimental values. The magnetic properties of the complex were investigated by electron paramagnetic resonance (EPR) spectroscopy. Further ultra-violet (UV)-visible spectral analysis was also performed to understand optical properties. The experimental UV-Vis data were associated with the calculated frontier molecular orbitals HOMO/LUMO and, molecular electrostatic potentials (MEP) are also investigated. Biological study of the complex against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Candida albicans showed very strong antibacterial activity with MIC values ranging from 128 mu g/ml to 1 mu g/ml concentration. The optimized complex is docked to the DNA Gyrase (3LPX) and gyrase tip IIA topoisomerase (3UC1). (c) 2020 Elsevier B.V. All rights reserved.