Browsing by Author "Ataç, A"
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Item Synthesis and vibrational spectroscopic study of some metal(II) halide and tetracyanonickelate complexes of isonicotinic acidAtaç, A; Bardak, FThe M(IN)(2)Ni(CN)(4) [where M: Cu, Mn, Zn, IN: Isonicotinic acid, abbreviated to M-Ni-IN] tetracyanonickelate and some metal halide complexes with the following stoichiometries: Cu(IN)X-2 (X:Br,I), Cd(IN)(2)X-2, (X:Cl,Br), and Zn(IN)(4)X-2 (X:Br,I) were synthesized for the first time. Their FT-IR spectra were reported in the 4000-400 cm(-1) region. Vibrational assignments were given for all the observed bands. The analysis of the vibrational spectra indicates that there are some structure-spectrum correlations. For a given series of isomorphous complexes, the sum of the difference between the values of the vibrational modes of uncoordinated isonicotinic acid that were coordinated to the metal ion isonicotinic acid was investigated and found to depend on the halogen for a given metal. The proposed structure of tetracyanonickelate complexes consists of polymeric layers of vertical bar M-Ni (CN)(4)vertical bar(infinity) with the isonicotinic acid molecules bound directly to the metal (M) atoms. Certain chemical formulae were determined using the elemental analysis results.Item Mechanical Properties and Hardness Results of the Medium Frequency Induction Sintered Iron Based Powder Metal BushingsÇavdar, U; Atik, E; Ataç, AIn this study; iron based powder metal (PM) bushing compacts were sintered via medium frequency induction heating system. Iron based powders were mixed with 2 wt.% copper (Cu), 0.3 wt.% carbon (C) and 1 wt.% zinc stearat (Zn-st) via V-Type mixer. PM compacts were sintered by 2 different sintering processes. One of them was conventional sintering method other was medium frequency induction sintering method. In conventional sintering process, PM bushing compacts were sintered under inert environmental at 1120 degrees C for 30 minutes. In medium frequency induction sintering process, PM bushing compacts were sintered between 30-50 kHz frequency (Medium frequency) at 2 kW, 1120 degrees C for 1 or 3 minutes under atmospheric environmental. Mechanical properties, densities and micro hardness' were investigated for all sintered processes. SEM and micro structural images were taken from polished broken surface of the sintered PM bushing compacts. 3 minutes induction sintered compacts were reached the compressive strength, microhardness and density values of the conventional sintered PM bushing compact.Item Single and binary nickel, copper, and zinc-based nanosized oxides as anode materials in lithium-ion batteriesEgesoy, E; Kap, O; Bardak, F; Horzum, N; Ataç, AThe demand for portable power sources with higher energy density and longer lifespan has prompted researchers to focus on developing better electrode materials for lithium-ion batteries (LIBs). Metal oxide nanoparticles have potential due to their low cost, high surface-area-to-volume ratio, strong reactivity, excellent size distribution, high theoretical capacities, and eco-friendly synthesis methods. However, there is still room for improvement in capacity retention and rate performance. To cope with this entail, the cycle performance of LIBs has been initially investigated utilizing single metal oxide anode materials including NiO, CuO, and ZnO nanostructures. Subsequently, binary oxides of Ni-Cu, Ni-Zn, and Cu-Zn have been synthesized to examine whether the binary structures boost the battery performance. NiCuO is the optimum anode material combining the benefits of NiO with the highest initial discharge capacity of 691 mAh g(-1) and the highest retention rate of CuO (49% after 30 cycles).Item Synthesis, spectroscopy, and characterization of some bis-nicotinamide metal(II) dihalide complexesAtaç, A; Yurdakul, S; Berber, SWe report synthesis of six new bis-nicotinamide metal(II) dihalide complexes [M(nia)(2)Cl(2); M = Mn, Co; nia:nicotinamide, M(nia)(2)Br(2); M = Mn, Hg; M(nia)(2)l(2); M = Cd, Cu], and their characterization by combining infrared spectroscopy with density functional theory (OFT) calculations. Infrared spectra indicate that ring-nitrogen is the active donor cite, and the atomic structure of the complexes is determined to be polymeric octahedral or distorted polymeric octahedral. Spin polarized electronic ground state is obtained for Mn, Co, and Cu halide complexes. The colors of the complexes also support the conclusion of octahedral coordination around the metal atoms, in agreement with OFT results. (C) 2011 Elsevier B.V. All rights reserved.Item Spectroscopic and luminescence properties of an isonicotinic acidCan, N; Ataç, A; Bardak, F; Can, SESAn isonicotinic acid N-oxide Zn(II) compound was characterized on the basis of elemental analysis. FTIR spectra of the compound and free isonicotinic acid N-oxide (INO) were recorded in the range 4000-400 cm(-1). Cathodoluminescence (CL) spectra from the Zn(INO)(2) complex were recorded. The luminescence data were interpreted in terms of the emission band at 470 inn. The green luminescence (similar to 470 nm) arises from Zn2+ transition T-4(1) ((4)G) --> (6)A(1) (S-6). It shows a weak vibronic structure. and short lifetimes less than 150 mu s. The lifetime and intensity of the signal are temperature dependent, and the parameters are reported for the 470 nm emission line.Item Structural characterization and luminescence properties of an isonicotinic acid N-oxide Mn(II) complexCan, N; Can, SES; Ataç, A; Bardak, FAn isonicotinic acid N-oxide Mn(II) compound was synthesized and characterized on the basis of elemental analysis and X-ray crystallography. In the complex, Mn(II) ions are coordinated by six water molecules, and the coordination number of the Mn(II) ion is six. FTIR spectra of the compound free isonicotinic acid N-oxide (INO) have been recorded in the range 4000-400 cm(-1) Cathodoluminescence (CL) spectra from the Mn(II) complex have been recorded. The luminescence data were interpreted in terms of the emission band at 480 nm. The green luminescence (similar to480 nm) arises from the Mn2+ transition T-4(1) ((4)G)-->(6)A(1) (S-6). It shows weak vibronic structure. short lifetimes less than 250 mus, and indicates that Mn2+ is octahedrally coordinated, occupying sites with similar distortions. The lifetime and intensity of the signal is temperature dependent, and the parameters are reported for the 480 nm emission line. (C) 2004 Elsevier Ltd. All rights reserved.Item Experimental and computational insights into the electronic structures and absorption-emission characteristics of coumarin, C-6H, C-153, and C-343 dyesKaraca, C; Bardak, F; Köse, E; Ataç, AThis paper explores the electronic structure and spectral characteristics of coumarin (C), C-6H, C-153, and C-343 in the protic polar solvent acetonitrile, combining computational methods via Density Functional Theory (DFT) and time-dependent Density Functional Theory (TD-DFT) with experimental analysis of UV-Vis and fluorescence spectra. The optoelectronic features of C, C-6H, C-153, and C-343 are primarily utilized in the solution phase for various applications, such as lasers and dye-sensitized solar cells. Computational studies were conducted using four different Modal Chemistry methods [MC1: CAM-B3LYP/6-311++G(d.p), MC2: CAM-B3LYP/6-31 + G(d.p), MC3: B3LYP/6-311++G(d.p), and MC4: B3LYP/6-31 + G(d.p)]. The excited state features were investigated based on TD-DFT/Polarizable Continuum Model-Linear Response and TD-DFT/Polarizable Continuum ModelState Specific formalisms. Molecular orbital configurations, molecular electrostatic potentials, and electron density difference isosurface of the dyes were analyzed to uncover the factors influencing the absorption and emission properties. The decomposed UV-Vis and fluorescence spectra of compounds indicate that emission characteristics are complex and contribute to low-lying energy transitions. The state-specific solutions provide more reliable estimates for smaller molecular structures with less intramolecular charge transfer, whereas the linear response approach excels when more electron-donating functional groups are present. The effect of the basis set in determining both absorption and emission features is almost negligible compared to Hartree-Fock exchange contributions in DFT functionals. B3LYP appears to provide satisfactory results for systems where long-range HF exchange is not as crucial.Item DFT, FT-IR, FT-Raman and NMR studies of 4-(substituted phenylazo)-3,5-diacetamido-1H-pyrazolesKinali, S; Demirci, S; Çalisir, Z; Kurt, M; Ataç, AWe present a detailed analysis of the structural and vibrational spectra of some novel azo dyes. 2-(Substituted phenylazo)malononitriles were synthesized by the coupling reaction of the diazonium salts, which were prepared with the use of various aniline derivatives with malononitrile, and then 4-(substituted phenylazo)-3,5-diamino-1H-pyrazole azo dyes were obtained via the ring closure of the azo compounds with hydrazine monohydrate. The experimental and theoretical vibrational spectra of azo dyes were studied. The structural and spectroscopic analysis of the molecules were carried out by using Becke's three-parameters hybrid functional (B3LYP) and density functional harmonic calculations. The H-1 nuclear magnetic resonance (NMR) chemical shifts of the azo dye molecules were calculated using the gauge-invariant-atomic orbital (GIAO) method. The calculated vibrational wavenumbers and chemical shifts were compared with the experimental data of the molecules. (C) 2011 Elsevier B.V. All rights reserved.Item Synthesis and vibrational spectroscopic studies of isonicotinamide metal(II) halide complexesAtaç, A; Yurdakul, S; Ide, SFourier transform infrared spectra (4000-200 cm(-1)) are reported for the metal (II) halide isonicotinamide complexes of the following stoichiometries: M(iso)(2)X-2 [M=Ni, Cu, Hg; X=Cl; iso=isonicotinamide], M(iso)(2)X-2 [M=Ni, Cu; X=Br], and CO(iso)(2)I-2. Vibrational assignments are given for all the observed bands. The Raman spectra (4000-100 cm(-1)) are reported for the three of these complexes. Also, the ESR spectra of these complexes are given. For a given series of isomorphous complexes the sum of the difference between the values of the vibrational modes of the free isonicotinamide and complexed ligand was found to increase in the order of the second ionization potentials of metals. The frequency shifts are also found to depend on the halogen. The studied metal halide complexes were characterized by X-ray powder diffraction patterns and FTIR spectra. Certain chemical formulas were determined using elemental analysis results. Finally, the geometry optimization method was used to predict three dimensional molecular geometries of the complexes by using the HYPERCHEM 5.0 the level of the theory molecular mechanic. (c) 2005 Elsevier B.V. All rights reserved.