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Öğe Catalytic degradation of organic dye using reduced graphene oxide-polyoxometalate nanocomposite(ELSEVIER SCIENCE SA, 2017) Ucar, Asuman; Findik, Mukerrem; Gubbuk, I. Hilal; Kocak, Nuriye; Bingol, HalukSilicotungstic acid (SiW) decorated reduced graphene oxide (rGO) nanocomposite (rGO-SiW) has been prepared and evaluated as a heterogeneous nanocatalyst for the degradation reactions of methylene blue (MB) and rhodamine B (RhB). The structural and morphological properties of rGO-SiW nanocomposite were investigated by various techniques such as Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), Atomic force microscopy (AFM) and Scanning electron microscope (SEM), which revealed the homogeneous and noncovalent anchoring of SiW nanoparticles on rGO sheets. The catalytic activity of rGO-SiW nanocomposite on the degradations of MB and RhB has been monitored using UV-visible absorption spectrometry in the presence of NaBH4 as the reducing agent at room temperature in water. The reduction reactions followed pseudo-first order kinetics and degradation were achieved in 34 min for MB and 81 min for RhB using rGO-SiW as catalysts. (C) 2017 Elsevier B.V. All rights reserved.Öğe ESR Characterization of Two Oxovanadium (IV) Schiff Base Complexes Derived from Tris(2-aminoethyl)amine(TAYLOR & FRANCIS INC, 2012) Sahin, Mustafa; Kocak, Nuriye; Sayin, Ulku; Yilmaz, MustafaThe compounds, C21H27N4O3(L-1) and C21H27N7(L-2), is a tripodal Schiff base that was obtained from the reaction of tris(2-aminoethyl)amine (tren) and furan-2-carbaldehyde and pyrole-2-carbaldehyde. The tripodal Schiff bases and their oxovanadium complexes have been characterized on the basis of the results of the elemental analysis, magnetic susceptibility measurements and spectroscopic studies FT-IR, H-1-NMR, UV-Vis, ESR, magnetic moment and thermal analysis (TGA). Job's method of continuous variation shows 3: 2 metal to ligand ratio.Öğe Microwave Assisted Synthesis of Chitosan Nanoparticles(TAYLOR & FRANCIS INC, 2011) Kocak, Nuriye; Sahin, Mustafa; Akin, Ilker; Kus, Mahmut; Yilmaz, MustafaChitosan nanoparticles (CHN) were prepared based on ionotropic gelation between low moleculer weight chitosan and sodium tripolyphosphate (TPP) under microwave irradiation. Particle size, zeta potential, and FT-IR techniques were used for characterization of CHN. The influence of reaction time on the nanoparticle size distribution was investigated, and the results showed that the microwave irradiation method evidently decreases the reaction times and particle size over the conventional method. It was determined by the results of the zeta potential measurements that synthesized CHN under microwave irradiation clearly exhibits more homogeneous and stable dispersion.Öğe A new anthracene derivative of calix[4]arene as a fluorescent chemosensor(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, 2013) Sahin, Ozlem; Sahin, Mustafa; Kocak, Nuriye; Yilmaz, MustafaA new anthracene derivative of calix[4]arene was synthesized as a highly fluorescent compound. This compound was examined for its fluorescent properties towards different metal ions (Li+, Na+, Mg2+, Ca2+, Ba2+, Ni2+, Cu2+, Zn-2+, Pb2+) by UV and fluorescence spectroscopy. On complexation by alkaline earth metal cations and transition metal cations, the fluorescence spectrum was quenched. In particular, Ca2 + caused greater than 98% quenching of the anthracene derivative of calix[4] arene.Öğe A Novel Chitosan Nanoparticle-Schiff Base Modified Carbon Paste Electrode as a Sensor for the Determination of Pb(II) in Waste Water(ESG, 2013) Kucukkolbasi, Semahat; Erdogan, Zehra Ozden; Barek, Jiri; Sahin, Mustafa; Kocak, NuriyeThis paper describes the preparation and electrochemical application of a modified carbon paste electrode with a new kind of chitosan nanoparticle-Schiff base for the determination of Pb(II) ions in waste water using differential pulse anodic stripping voltammetry (DPASV). Firstly a new kind of chitosan nanoparticle-Schiff base (CNSB) was synthesized by chitosan nanoparticle reaction with 2,4-dihydroxybenzaldehyde. CNSB structure was characterized by FT-IR spectroscopy, elemental analysis, particle size and zeta potential. Afterwards, a novel, simple and effective chemically modified carbon paste electrode with CNSB was prepared and characterized using scanning electronic microscopy (SEM-EDX) and anodic stripping voltammetry. The modified electrode showed only one oxidation peak in the anodic scan at -0.35 V (vs. Ag/AgCl) for the oxidation of Pb(II). The electrochemical properties and applications of the modified electrode, including the pH, supporting electrolyte, preconcentration time, reduction potential and time, and percentage of modifier were investigated. The best voltammetric response was observed for a paste composition of 73.7% (w/w) of graphite powder, 5.3% (w/w) of chitosan and 21% (w/w) of paraffin oil, with 0.2 mol L-1 NaAc solution at pH 6.0 as supporting electrolyte, preconcentration time of 600 s, a reduction potential of -0.1 V and reduction time of 10 s. The new electrode displays excellent response to Pb(II) which is linear in the range from 1x10(-6) to 1x10(-4) mol L-1, with a correlation coefficient of 0.998 and a detection limit of 7.24x10(-7) mol L-1.Öğe Synthesis and characterization of novel nano-chitosan Schiff base and use of lead (II) sensor(ELSEVIER SCIENCE BV, 2012) Kocak, Nuriye; Sahin, Mustafa; Kucukkolbasi, Semahat; Erdogan, Zehra OzdenA new kind of nano-chitosan Schiff base ligand (CHNS) with particle size of 34 nm was formed by the reaction between the 2-amino groups of glucosamine residue of nano-chitosan and a 2,5-dihydroxybenzaldehyde. The chemical structures of the nano-chitosan and nano-chitosan Schiff base were characterized by FT-IR spectra, particle sizer, zeta potential, and elemental analysis. A new, simple and effective chemically modified carbon paste electrode with CHNS was prepared and used as a lead (II) sensor. The prepared electrode was characterized using scanning electronic microscopy (SEM-EDX) and cyclic voltammetry (CV). The modified electrode showed only one oxidation peak in the anodic scan at -0.34 V (vs. Ag/AgCl) for the oxidation of lead (II). The dedection limit (LOD) was calculated as 1.36 x 10(-7) for a 10-min preconcentration time at pH 6.0. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.Öğe Synthesis and Characterization of Sporopollenin-Supported Schiff Bases and Ruthenium(III) Sorption Studies(SPRINGER, 2012) Sahin, Mustafa; Gubbuk, Ilkay Hilal; Kocak, NuriyeTwo Schiff base derivatives, (2-pycolylimino)benzen-1,4-diol and (2-pyridylimino)benzen-1,4-diol) were immobilized onto sporopollenin (Lycopodium clavatum) surfaces. The compounds were fully characterized by an infrared spectroscopy, elemental analysis, scanning electron microscopy, and X-ray diffraction techniques. The sorption capacities of the immobilized surfaces toward Ru(III) ions were investigated by batch sorption experiments. For the sorption experiment, the Ru(III) concentration, initial pH, and the temperature effects were studied. The isotherm data of Ru(III) ions were correlated reasonably well as a Freundlich sorption isotherm. The thermodynamic studies showed that the Ru(III) sorption onto immobilized sporopollenin derivatives is a non-spontaneous, endothermic and physical reaction.Öğe Synthesis of asymmetrical tridendate Schiff bases and metal complexes and investigation of anticarcinogen effects on human colon and cervical cancers(TAYLOR & FRANCIS INC, 2017) Sahin, Mustafa; Korkmaz, Hatice; Kocak, Nuriye; Sahin, Ozlem; Karakurt, Serdar; Yilmaz, MustafaThe metal complexes of Zn(II), Ni(II), Cu(II) and Pb(II) with asymmetrical Schiff bases were synthesized. The asymmetrical Schiff base was obtained through the condensation of 1,2-phenylenediamine, 4-methyl-1,2-phenylenediamine, 2-hydroxy-1-napthaldehyde and biphenyl-4-carbaldehyde. The new Schiff base ligands (L-1' and L-2') and their metal complexes were characterized by TG/DTG, FT-IR, H-1-NMR, UV-Vis, ESR, powder XRD, elemental analysis, magnetic moment and fluorescence studies. The powder XRD studies indicate that Co(II) and Cu(II) complexes are amorphous, while Ni(II) and Zn(II) complexes are crystalline. The anticarcinogenic effects of L-1' and L-2' were also investigated against colon (SW-620) and cervical cancer (HeLa) cell lines and compound L-2' was found to possess the highest anticarcinogenic potential, with 16.7 mu M and 27.5 mu M of IC50 values for HeLa and SW620 cells, respectively.Öğe Synthesis of Crosslinked Chitosan Possessing Schiff Base and Its Use in Metal Removal(SPRINGER, 2012) Kocak, Nuriye; Sahin, Mustafa; Arslan, Gulsin; Ucan, H. IsmetA chitosan resin derivatized with Schiff bases was synthesized by using a crosslinked chitosan (CCTS) as base material. We first synthesized N-benzylidene chitosan (CTB) by the reaction of benzaldehyde with chitosan. After this reaction crosslinking was carried out in the usage of epichlorohydrine (ECH) as a crosslinking agent. The Schiff base was removed by reacting diluted ethyl alcohol hydrochloride solution to give crosslinked chitosan (CCTS). The CCTS was suspended in a mixture of ethyl alcohol/deionized water followed by the addition of epichlorohydrine and by this way crosslinked chitosan-epichlorhydrine (CCTS-ECH) resin was synthesized. After the reaction was completed, the product was filtered, washed with ethyl alcohol and deionized water and dried in vacuum. The two novel polymeric ligands (CCTS-ECH-DHSalophen and CCTS-ECH-DHDPE) were synthesized by the reaction of CCTS-ECH with N,N'-bis(2,5 dihydroxybenzylidene)-1,2-diaminobenzene (DHSalophen), and N,N'-bis(2,5 dihydroxybenzylidene)-4,4'-diaminodiphenylether (DHDPE). The structures of the ligands were characterized by elemental analysis, infrared spectroscopy(FT-IR), scanning electron microscopy(SEM) and thermogravimetric analysis (TGA/DTA). Adsorption experiments (pH dependency, kinetics, and equilibrium) of compounds toward Cr(VI) from waste water were carried out at 25 degrees C.Öğe Synthesis of Crosslinked Chitosan with Epichlorohydrin Possessing Two Novel Polymeric Ligands and Its Use in Metal Removal(SPRINGER, 2011) Sahin, Mustafa; Kocak, Nuriye; Arslan, Gulsin; Ucan, Halil IsmetOne of the major applications of chitosan and its derivatives is based on its ability to bind strongly toxic metal ions. In this work, two novel polymeric ligands were synthesized to investigate the adsorption properties of Cu(II), Pb(II), Zn(II) and Ni(II) ions in an aqueous solution. To prevent the reaction between as the C-2 amine group of chitosan and ECH, the C-2 amine group was protected N-benzylidene chitosan (CTB). After the reaction with ECH to give N-benzaldehyde crosslinked chitosan (CCTB), the Schiff base was removed in a dilute ethanol hydrochloride solution to obtain CCTS which has free amine group. CCTS-ECH was synthesized by the reaction of CCTS and ECH. Then, CCTS-ECH was reacted with (2-hydroxyphenylimino)methylbenzene-1,4-diol (HBD) and N,N'-bis(2,5-dihydroxybenzylidene)-1,4-diaminobenzene (DHDB) to give ligands CCTS-ECH-HBD and CCTS-ECH-DHDB. The batch experiments showed that two novel polymeric ligands can be effectively used to remove Cu(II) from water.Öğe Synthesized of Sporopollenin-Immobilized Schiff Bases and Their Vanadium(IV) Sorption Studies(SPRINGER, 2012) Kocak, Nuriye; Sahin, Mustafa; Gubbuk, Ilkay HilalThis study investigated the potential use of a biologic polymer Lycopodium clavatum spores (Sporopollenin) for removal of vanadium ions (V(IV)) from aqueous solution. Three Schiff base derivative compounds immobilized sporopollenin were prepared and characterized. Immobilized sporopollenin was characterized via a scanning electron microscope, elemental analysis, infrared spectroscopy and thermal analysis techniques. The sorption capacities of the immobilized surfaces toward V(IV) ions were investigated by batch sorption experiments. V(IV) concentration, initial pH and the temperature effects were studied. The isotherm data of V(IV) ions were correlated reasonably well both Langmuir, Freundlich sorption isotherm. The thermodynamic studies showed that the V(IV) sorption onto immobilized sporopollenin derivatives is a spontaneous, endothermic and a chemical reaction.Öğe Synthetic Access to New Carbamate and Thiocarbamate Derivatives from Pyridinecarbaldehyde Oximes and Hydroxypyridines(TAYLOR & FRANCIS INC, 2011) Kocak, Ahmet; Ahmetli, Gulnare; Kocak, Nuriye; Malkondu, Sait; Yaylaci, Aysegul; Kurbanli, Sultan[image omitted] The synthesis of pyridine carbamate and thiocarbamate derivates is described. A series of oxime carbamate and thiocarbamate derivatives were synthesized by the addition of 2-, 3-, and 4-pyridinecarbaldehyde oximes to isocyanates and isothiocyanates. Furthermore, carbamate and thiocarbamate derivatives of pyridine were synthesized by the addition of 2-, 3-, and 4-hydroxy pyridine to isocyanates and isothiocyanates. Their structures were confirmed by both analytical and spectral data.Öğe The Use of Voltammetry for Sorption Studies of Pb2+ from Aqueous Media using Schiff Base Immobilized Biologic Polymer Material(SPRINGER INTERNATIONAL PUBLISHING AG, 2013) Kucukkolbasi, Semahat; Erdogan, Zehra Ozden; Kocak, Nuriye; Sahin, Mustafa; Gubbuk, Ilkay HilalAdsorption by low-cost adsorbents and biosorbents is recognized as an effective and economic method for low-concentration heavy metal. The purpose of this study was to investigate the possibility of the utilization of N,N'-bis(2,5-dihydroxybenzylidene)-1, 4-diaminobenzene (DHDB)-immobilized sporopollenin (Schiff base-immobilized sporopollenin, Sp-DHDB) as a sorbent for removal of lead (II) ion from aqueous solution. The effects of different parameters (such as sorbate concentration, sorbent dosage, and pH of the medium) were investigated by differential pulse anodic stripping voltammetry (DPASV) technique. The experimental data were analyzed by the Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) isotherms. Equilibrium data fitted well with the Freundlich model and the procedure developed was successfully applied for the removal of lead ions in aqueous solutions. This investigation reveals a new, simple, environmentally friendly, and cost-effective method for the removal of lead ions from aqueous solutions by a new Sp-DHDB material.Öğe Zn(II), Ni(II), Cu(II) and Pb(II) complexes of tridentate asymmetrical Schiff base ligands: Synthesis, characterization, properties and biological activity(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Sahin, Mustafa; Kocak, Nuriye; Erdenay, Damla; Arslan, UgurNew asymmetrical tridentate Schiff base ligands were synthesized using 1,2-phenylenediamine, 4-methyl-1,2-phenylenediamine, 2-hydroxy-1-napthaldehyde, 9-anthracenecarboxaldehyde. Schiff base ligands and their metal complexes were synthesised and characterized by using FT-IR, H-1 NMR, C-13 NMR, UV-Vis, XRD, ESR, elemental analysis and fluorescence studies. The antimicrobial activity of the ligands and their metal complexes were studied against Staphylococcus aureus ATCC 29213, S. aureus ATCC 25923, Streptococcus mutans RSHM 676, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853. The determination of the antibacterial activity was done using the broth microdilution methods. In general, it has been determined that the studied compounds have MIC values similar to Gram-positive and Gram-negative bacteria. It has been found that Ni, Pb, Zn derivatives of HL1A and ZnL(2)A has lower MIC values than ampicillin for P. aeruginosa ATCC 27853 strain. (c) 2012 Elsevier B.V. All rights reserved.
