Yazar "Colak, Alper Tolga" seçeneğine göre listele

Listeleniyor 1 - 8 / 8
  • [ X ]
    Öğe
    3D Polyoxometalate-Functionalized Graphene Quantum Dots with Mono-Metallic and Bi-Metallic Nanoparticles for Application in Direct Methanol Fuel Cells
    (Electrochemical Soc Inc, 2016) Colak, Alper Tolga; Eren, Tanju; Yola, Mehmet Lutfi; Besli, Erdem; Sahin, Onur; Atar, Necip
    A fuel cell is an electrochemical cell that converts a source fuel into an electrical current. It generates electricity inside a cell through reactions between a fuel and an oxidant, triggered in the presence of an electrolyte. Fuel cells have been attracting more and more attention in recent decades due to high-energy demands, fossil fuel depletions, and environmental pollution throughoutworld. Afacile and cost-effective catalysts have been developed on polyoxometalate (NaPWO) functionalized graphene quantum dots (GQDs) with several mono-metallic and bi-metallic nanoparticles such as platinum nanoparticles (PtNPs), palladium nanoparticles (PdNPs) and platinum-palladium nanoparticles (Pt-PdNPs). The successful synthesis of nanomaterials and the prepared glassy carbon electrode (GCE) surfaces were confirmed by transmission electron microscope (TEM), X-ray photo electron spectroscopy (XPS), scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS) and X-ray diffraction (XRD) method. According to TEM images, the average particle sizes of PtNPs and PdNPs were found to be approximately 20-30 nm. The Pt-PdNPs/NaPWO/GQDs also exhibited a higher peak current for methanol oxidation than those of comparable PdNPs/NaPWO/GQDs and PtNPs/NaPWO/GQDs, thus providing evidence for its higher electro-catalytic activity. (C) 2016 The Electrochemical Society. All rights reserved.
  • [ X ]
    Öğe
    A new Keggin-type polyoxometalate catalyst for degradation of aqueous organic contaminants
    (Elsevier, 2017) Olgun, Asim; Colak, Alper Tolga; Gubbuk, I. Hilal; Sahin, Onur; Kanar, Ebru
    In this study, a new polyoxometalate,K-16[Ni(H2O)(6)](2)[BW12O40]4(center dot)48H(2)O (1) was synthesized at room temperature and characterized by X-ray single crystal diffractions, elemental analyses, IR spectra, and thermo gravimetric analyses (TGA). Crystal structure analysis reveals that compound 1 exhibits a supramolecular structure containing one Keggin-type [BW12O40](4) heteropoly anion. The catalytic properties of this molecule for the degradation of Methyl red (MR), Rhodamine B (RhB), Methyl orange (MO) and Congo red (CR) were investigated. The results show that the compound 1 is a promising catalyst candidate for dye degradation. (C) 2016 Elsevier B.V. All rights reserved.
  • [ X ]
    Öğe
    Facile and green fabrication of silver nanoparticles on a polyoxometalate for Li-ion battery
    (Springer Heidelberg, 2015) Eren, Tanju; Atar, Necip; Yola, Mehmet Lutfi; Karimi-Maleh, Hassan; Colak, Alper Tolga; Olgun, Asim
    In the present study, we report the green and one-pot synthesis of silver nanoparticles (AgNPs) on as-prepared novel polyoxometalate {[Ni-2,Ni-5(Hpen)(4)(PW9O34)] center dot 5H(2)O} (POM) without any reducing agent and its application as improved anode material for lithium-ion batteries (LIBs). The structure of the AgNPs involved POM (AgNPs/POM) nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The synthesized POM was also characterized by elemental analysis and thermal analysis. The electrochemical performances of the POM, AgNPs, and AgNPs/POM composites were measured for charge/discharge specific capacities at different current rates in CR2032 coin-type cells. The prepared AgNPs/POM composite showed a high specific gravimetric capacity of about 1760 mAh g(-1) and long-term cycle stability.
  • [ X ]
    Öğe
    Self-assembly of a new building block of {BMo12O40} with excellent catalytic activity for methylene blue
    (Pergamon-Elsevier Science Ltd, 2019) Findik, Mukerrem; Ucar, Asuman; Colak, Alper Tolga; Sahin, Onur; Bingol, Haluk; Sayin, Ulku; Kocak, Nuriye
    A novel organic-inorganic hybrid of 2,2'-bipyridyl (2,2'-bipy) linked covalently with the first inorganic framework based on boron-containing Keggin-type heteropolymolybdate anion [BMo12O40](5-) has been hydrothermally synthesized in aqueous solution. The crystal structure was fully characterized by elemental analyses, single crystal X-ray diffraction, Fourier-transform infrared spectrum (FT-IR), powder X-ray diffraction (XRD), Ultraviolet-visible spectroscopy (UV-Vis) and electron paramagnetic resonance (EPR) analysis. The catalytic performance of the synthesized catalyst was studied in degradation of methylene blue (MB) at ambient temperature. The catalyst exhibited excellent degradation against MB with a rate constant of 0.506/m, which was much higher than those by other polyoxometalate catalysts. Moreover, it was found to be easily separated from the reaction solution and recycled up to five times without significant loss of degradation activity. (C) 2019 Elsevier Ltd. All rights reserved.
  • [ X ]
    Öğe
    Sodium salt of boron-substituted first keggin-type polyoxometalate; synthesis, crystal structure and investigation of antimicrobial activities
    (Pergamon-Elsevier Science Ltd, 2025) Besli, Erdem; Colak, Ferdag; Sahin, Onur; Dikim, Selinsu; Colak, Alper Tolga
    This study aims to investigate the antimicrobial activity of the boron-containing polyoxometalate (BPOM) Na7[H1.5BW12O40]center dot 6en (1), synthesized as a single crystal. The structural and thermal properties of this novel BPOM were thoroughly analyzed using FT-IR, TGA, and X-ray diffraction (XRD) techniques. The incorporation of boron into these structures is believed to enhance their antimicrobial properties. The antimicrobial activity of the compound was evaluated against two Gram-positive bacteria (Staphylococcus aureus, Bacillus cereus), three Gramnegative bacteria (Escherichia coli, Legionella spp., Legionella pneumophila sg 2-15), and a yeast (Candida albicans) using disc diffusion and tube dilution (Minimal Inhibition Concentration) methods. The results demonstrated that the synthesized compound exhibited significant antimicrobial activity, particularly against Bacillus cereus (Gram-positive) and Legionella spp. and Legionella pneumophila sg 2-15 (Gram-negative).
  • [ X ]
    Öğe
    Syntheses, crystal structures, spectroscopic and thermal characterisations of new homophthalate compounds
    (Pergamon-Elsevier Science Ltd, 2015) Orhan, Oguzhan; Colak, Alper Tolga; Sahin, Onur; Tunc, Tuncay; Celik, Omer
    In this study, four new M(II)-homophthalate complexes with 2,2'-bipyridine (bipy). N,N-dimethylethylenediamine (dmen), imidazole (im) and 1,10-phenanthroline (phen), namely [Mn(hmph)(bipy)(H2O)(2)](n) (1), [Ni(hmph)(dmen)(2)(H2O)]center dot H2O (2), [Cu(hmph)(im)(2)](n) (3) and [Cu(phen)(2)Cl]center dot(Hhmph)center dot(H(2)hmph) (4) (H(2)hmph = homophthalic acid) have been synthesised. Elemental and thermal analyses and IR spectroscopic studies have been performed to characterise the complexes. The molecular structures of the complexes have been determined by single crystal X-ray diffraction. The geometries around the Mn(II) (1) and Ni(II) (2) ions are distorted octahedrons. Each Cu(II) ion exhibits penta-coordination with a distorted square-pyramidal geometry in 3 and a distorted trigonal-bipyramidal geometry in 4. In 1 and 3, hmph is a bridging ligand that forms 1D and 2D coordination polymers, which are extended into 3D layers by hydrogen bonding and pi-pi interactions. (C) 2014 Elsevier Ltd. All rights reserved.
  • [ X ]
    Öğe
    Synthesis, characterization, and use of lanthanide chelate of β-diketonate based ligand as a luminescent biolabel
    (Turkish Chemical Society, 2021) Yuvayapan, Semanur Sen; Colak, Alper Tolga; Sahin, Onur; Celik, Cumali
    In this study, we aimed to synthesize a β-diketonate-based ligand and its Eu(III) complex which are used for luminescent biolabel. For this purpose, we chose acetophenone as the starting material which contains methyl group at the alpha position of the ketone group. Firstly, we obtained 4,4,5,5,6,6,7,7-octafluoro-3,8-dihydroxy-1,10-diphenyldeca-2,8-diene-1,10-dione (H2ODIT) ligand in a reaction between acetophenone and diethyloctafluoroadipate with Claisen condensation. This ligand was characterized by1H-NMR,13C-NMR, and mass spectral analyses. We obtained a single crystal H2ODIT as characterized by X-ray analysis. At the second step, in order to bind H 2ODIT to the antibody, it is reacted with chlorosulfonic acid. As a result of this reaction, the functional group of-ClSO2 was bound to the structure. The structure of H2CODIT was characterized by NMR and mass spectral analysis. In the third step, to understand the usability of the ligand as a biolabel, the complex compound was synthesized with EuCl3. The complex compound was excited with UV light at 306 nm wavelength, specific hypersensitive5D0 →7F2 phosphorescence electronic transition of the Eu(III) was observed which proved that the luminescent H2CODIT molecule can work as a biolabel. © 2021, Turkish Chemical Society. All rights reserved.
  • [ X ]
    Öğe
    The syntheses, crystal structures, spectroscopic and thermal characterization of new pyridine-2,5-dicarboxylate compounds
    (Pergamon-Elsevier Science Ltd, 2015) Dogan, Deniz; Colak, Alper Tolga; Sahin, Onur; Tunc, Tuncay; Celik, Omer
    In this study, four new M(II)-isocinchomeronic acid (pyridine-2,5-dicarboxylic acid) complexes with ethylenediamine (en) and 2,2'-bipyridine (bipy), namely [Co(en)(3)][Co(pydc)(2)(H2O)(2)]center dot 2H(2)O (1), [Ni(Hpydc)(2) (H2O)2] (2), [Cu(en)(2)(H2O)][Cu-3(Pydc)(4)(en)(2)(H2O)(2)]center dot 3H(2)O (3) and [Cu(bipy)(3)][Cu(pydc)(bipy)(2)]center dot 2Cl center dot 12H(2)O (4) (H(2)pydc = pyridine-2,5-dicarboxylic acid), have been synthesised. Elemental, thermal analyses and IR spectroscopic studies have been carried out in order to characterise the complexes. The molecular structures of the complexes have been determined using single crystal X-ray diffraction. The geometry displayed by the Co(II) (1) and Ni(II) (2) ions is distorted octahedral. The Cu(II) ions display a square pyramidal geometry and distorted octahedral geometry in 3, while each Cu(II) ion exhibits a distorted octahedral geometry in 4. Molecules of each complex are linked into a 3D framework structure by N-H center dot center dot center dot O, O-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds. (C) 2015 Elsevier Ltd. All rights reserved.