Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Article Citation - WoS: 13Citation - Scopus: 15Synthesis of Poly-2 Methacrylate-Montmorillonite Nanocomposite Via in Situ Atom Transfer Radical Polymerization(Cambridge University Press, 2008) Oral, Ayhan; Shahwan, Talal; Güler, ÇetinThe poly-2-hyroxyethyl methacrylate (PHEMA)/clay nanocomposite was synthesized by in situ atom transfer radical polymerization (ATRP) from initiator moieties immobilized within the silicate galleries of the clay particles. To produce organically modified montmorillonite (MMT) that has ATRP initiator moiety, a new catalyst that consists of quaternary ammonium salt moiety and an initiator moiety was synthesized. This initiator was intercalated into the interlayer spacing of the MMT. The polymerization reaction was carried out in a mixed solvent system consisting of methyl ethyl ketone and 1-propanol at 50 °C, using the initiator that has been already synthesized with a copper bromide catalyst. The 2, 2′-bipyridyl (bpy) complex was used as ligand. The products were characterized via Fourier transform infrared, nuclear magnetic resonance (1H NMR, 12C NMR), transmission electron microscopy, x-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. © 2008 Materials Research Society.Article Reactions of the Solvent-Stabilized Compound [moocl2(thf)2] With Aromatic Nitrogen Donor Ligands: Spectroscopic Characterization and Semiempirical Am1* Calculations(TUBITAK, 2009) Kılıçkaya, Gülşah; Doğan, Başak; Acar, Nursel; Sözüer, Hikmet IşılReaction of the solvent-stabilized dioxo-molybdenum(VI) compound [MoO2 Cl2 (THF)2]withP Ph3 yielded the oxomolybdenum(IV) species [MoOCl2 (THF)2](1) by the removal of one oxygen atom as PPh3 O. The complexes [MoOCl2 (=NC6 H4 CN)] 2,[MoOCl2 (CNC6 H4 OH)] 3,[MoOCl2 (=NC6 H4 NH2)] 4,and [MoOCl2 (=NC6 H4 OCH3)] 5, were synthesized by the reactions of [MoOCl2 (THF)2]with XC6 H4 Y(X =NH2, Y = CN; X= CN, Y = OH; X = Y = NH2;X=NH2,Y=OCH3). All the new compounds were characterized by elemental analyses, and FTIR, UV-Vis, and 1 H and 13 C-NMR spectra. Geometrical parameters and molecular orbital calculations showed that compounds 2-5 are stabilized by a charge transfer between the Mo center and the phenyl ring.Article Citation - WoS: 7Citation - Scopus: 8Evaluation of Dissolution Methods in the Presence of High Chloride Content for the Determination of Germanium in Geological Matrices by Hydride Generation Atomic Absorption Spectrometry(Japan Society for Analytical Chemistry, 2001) Abbasi, Husam U.; Eroğlu, Ahmet Emin; Anwari, Mohammad A.; Volkan, MürvetThe sample dissolution is probably the most crucial step in the determination of germanium in geological and metallurgical samples due to formation of volatile germanium compounds during the course of dissolution. It has been stated that this is especially true for the samples having high sulfide and/or chloride content.Article Citation - WoS: 11Citation - Scopus: 2Synthesis of Α,β-Unsaturated Ketones by Rhodium-Catalyzed Carbonylative Arylation of Internal Alkynes With Arylboronic Acids(Georg Thieme Verlag, 2008) Kuş, Melih; Aksın Artok, Özge; Ziyanak, Fırat; Artok, LeventThe Rh-catalyzed reaction of arylboronic acids with internal alkynes under a CO atmosphere in the presence of an acid additive afforded α,β-unsaturated ketones as the major products. Hydroacylation of internal alkynes, except in the case of diaryl acetylenes, proceeded in syn fashion, yielding the E-configured isomer. A mixture of E- and Z-isomers was obtained with diphenyl acetylene. Reactions were also highly regioselective for various nonsymmetric alkynes.Article Citation - WoS: 21Citation - Scopus: 21Retention of Aqueous Ba2+ Ions by Calcite and Aragonite Over a Wide Range of Concentrations: Characterization of the Uptake Capacity, and Kinetics of Sorption and Precipitate Formation(The Geochemical Society of Japan, 2007) Tunusoğlu, Özge; Shahwan, Talal; Eroğlu, Ahmet EminThe uptake of aqueous Ba2+, ions by abiogenic calcite and aragonite was studied over a wide range of concentration; 1.0 × 101, 5.0 × 101, 1.0 × 102 5.0 × 102, 1.0 × 103, 5.0 × 104, and 1.0 × 104 mg/L. The uptake process was characterized using ICP-AES, XRPD, SEM/EDS, and FTIR techniques. Up to the initial concentration of 5.0 × 102 mg/L, the uptake of Ba2+ ions was fast and obeyed Lagergren's kinetic model. The equilibrium data were adequately described using Freundlich isotherm model. The overgrowth of BaCO3 (witherite) took place at higher concentrations, in a kinetically slow process and enhanced the uptake of Ba2+ ions. Quantitative XRPD was used to evaluate the fractions of precipitated BaCO3 on calcite and aragonite minerals and monitor their variation with time. At all the studied concentrations, aragonite showed higher removal capacity of Ba2+ and faster uptake kinetics than did calcite. The precipitated crystals appeared to predominantly possess olivary-like morphology with an average particle size of 1-2 μm. EDS was used to reveal the elemental quantities of Ba and Ca after BaCO3 formation on calcite and aragonite surfaces. FTIR spectroscopy was employed to analyze the vibrational modes in carbonate mixtures upon incorporation of Ba2+ by sorption and precipitation mechanisms.Article Citation - WoS: 11Citation - Scopus: 13Study of the Scavenging Behavior and Structural Changes Accompanying the Interaction of Aqueous Pb2+ and Sr2+ Ions With Calcite(The Geochemical Society of Japan, 2005) Shahwan, Talal; Zünbül, B.; Akar, DilekThe uptake of Pb2+ and Sr2+ ions from aqueous solutions by calcite was studied at various initial concentrations and pH conditions using the batch method under ambient conditions. XRPD, SEM/ EDS, AAS/AES, and DRIFT techniques were used in characterizing the sorption process. The results indicated that the retention mechanism of Ph2+ and Sr2+ ions ranged from ion incorporation to precipitate overgrowth (cerussite, hydrocerussite for Pb, strontianite for Sr) depending on the concentration and pH conditions. The calcite structure seemed to be entirely vanishing upon formation of cerussite and hydrocerussite while partial dissolution of calcite occurred upon strontianite formation. The formation of precipitates showed rapid kinetics, and equilibrium seemed to be reached within about an hour from the start of mixing. SEM analysis showed that cerussite, hydrocerussite, and strontianite had columnar prismatic-like, tabular hexagonal-like, and needle-like morphologies. Based on a nine-month observation period, dry samples of hydrocerussite seemed to show more morphological stability than cerussite. EDS analysis indicated that Pb2+ sorption is more favored than that of Sr2+, particularly in the phase of precipitate overgrowth. DRIFT analysis indicated a change in the symmetry of the carbonate groups in calcite matrix upon uptake of Pb2+ and Sr2+ cations.Article Citation - WoS: 2Citation - Scopus: 3Synthesis and Characterization of Nitrosyl[tris(3,5dimethylpyrazolyl) Borato]molybdenum Complexes Containing Aryloxo, Arylamido and Arylcyano Ligands(TUBITAK, 2005) Sözüer, Hikmet Işıl; Dülger İrdem, SeçkinerThe complexes [MoTp*(NO)X(ZC6H4CN-p)] [Tp* = 3,5-dimethylpyrazolyl; X = Cl, Z = O and NH; X = I, Z = CN) were prepared and characterized using 1H-NMR, IR, FAB mass spectroscopy and micro analysis.Article Citation - WoS: 5Citation - Scopus: 6Synthesis, Spectroscopic Characterization and X-Ray Crystal Structures of Oxo-Bridged Oxo(haloaryl) Imido Hydrotris(3,5-Dimethylpyrazolyl)borate Molybdenum(v) Complexes(Taylor and Francis Ltd., 2005) Sözüer, Hikmet Işıl; Dülger İrdem, Seçkiner; Jeffery, John J.; Hamidov, HayrullahReaction of the oxomolybdenum(V) precursor [MoTp*(O)Cl2] (Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate) with m-fluoroaniline, H2NC6H4F, in toluene afforded the pair of geometric isomers of [MoTp*(O)Cl](μ-O)[MoTp*(Cl)(≡NC 6H4F)] (1a, cis; 1b, trans). Similarly the reaction with m-iodoaniline yielded the compound [MoTp*(O)Cl](μ-O)[MoTp*(Cl) (≡NC6H4I)] (2). This is a new synthetic method for preparing Mo-O-Mo bridged oxo(imido) molybdenum(V) species by double deprotonation of the anilines. The complexes were characterized by IR and 1H-NMR. spectroscopy, FAB mass spectrometry, elemental analysis and X-ray crystallography which revealed that the two chloro ligands are trans to each other in 1b and 2, whereas they are cis to each other in 1a. All compounds have Mo-O-Mo linkages and near linear arylimido moieties.Article Citation - WoS: 30Citation - Scopus: 30Glycidyl-Methacry Late-Based Electrospun Mats and Catalytic Silver Nanoparticles(John Wiley and Sons Inc., 2008) Demir, Mustafa Muammer; Uğur, Gökçe; Gülgün, Mehmet A.; Menceloğlu, Yusuf Z.P(AN-GMA) and PGMA fibers coated with monodisperse silver nanoparticles have been prepared by a combination of electrospinning and electroless plating. The morphology of the electrospun fibers remains unchanged after surface hydrazination. Oxidation of hydrazine in an ammoniacal solution of AgNO 3 reduces and deposits silver atoms along the fiber surface, which then coalesce to Ag particles. The size of the silver nanoparticles is varied between 20-60 nm. Since the density of the active sites for silver reduction is lower in P(AN-GMA), a smaller particle size could be obtained. The catalytic activity of the silver nanoparticles has been confirmed.Article Citation - WoS: 15Aggregation of Fillers Blended Into Random Elastomeric Networks: Theory and Comparison With Experiments(John Wiley and Sons Inc., 2006) Demir, Mustafa Muammer; Menceloğlu, Yusuf Ziya; Erman, BurakA theoretical model describing aggregation of filler particles in amorphous elastomers is proposed. The model is based on a counting technique originally used in genome analysis to characterize the size and distribution of overlapping segments randomly placed on a DNA molecule. In the present model, the particles are first assumed to aggregate randomly upon mixing into the elastomer and then-sizes are calculated. The sizes and distributions of aggregates are also studied in the presence of attractive interparticle forces. Results of the proposed model are compared with experimental data on silica-filled end-linked poly(dimethyl-siloxane) networks. Comparison of the theory and experiment shows that the random aggregation assumption where no attractive forces exist between the particles is not valid and a significant attraction between the silica particles is needed in the theory to justify the experimental data obtained using atomic force microscopy. For filler content below 1.45 vol.-%, the model agrees, qualitatively, with experiment and shows the increase in cluster size with increasing amount of filler. It also explains the increase in the dispersion of aggregate sizes with increasing amount of filler.