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Öğe Copper(II)-directed static excimer formation of an anthracene-based highly selective fluorescent receptor(PERGAMON-ELSEVIER SCIENCE LTD, 2015) Malkondu, Sait; Turhan, Dilek; Kocak, AhmetA novel 'turn-on' fluorescent receptor methyl 3-((anthracen-9-ylmethylene)amino)benzoate (MAR) with anthracene as the fluorophore and methyl 3-aminobenzoate as a metal ion chelating center has been designed and synthesized. The ability of the prepared receptor to detect metal ions has been evaluated by the changes in its emission intensity. MAR demonstrates high selectivity and sensitivity for Cu2+ among the nineteen metal ions examined in MeCN. The interaction of MAB with Cu2+ causes a significant enhancement in emission intensity due to the combination of a unique anthracenyl static excimer formation, the restricted C=N isomerization and the suppression of highly efficient photoinduced electron transfer (PET) process. The disassociation of the excimer species to monomers is directed by temperature, Cu2+ concentration and solvent fraction. Furthermore, the considerable 'off-on' fluorescence response or the conversion of the excimer species to monomers concomitantly led to the apparent color changes, which could also be identified easily by the naked eye using a UV lamp. (C) 2014 Elsevier Ltd. All rights reserved.Öğe Immobilization of Two Azacrown Ethers on Chitosan: Evaluation of Selective Extraction Ability Toward Cu(II) and Ni(II)(TAYLOR & FRANCIS INC, 2009) Malkondu, Sait; Kocak, Ahmet; Yilmaz, MustafaTwo Schiff base-type chitosan-azacrown ethers were prepared by a reaction of chitosan (CTS) with N-(4'-formylphenyl)aza-crown ethers, and they were converted to secondary-amino derivatives by the reduction of CTS-azacrown ethers with sodium borohydride. Their structures were confirmed by elemental analysis, infrared spectra and thermogravimetric analysis. The ability of these adsorbents to extract Cu(II) and Ni(II) ions from water by a solid-liquid extraction process was studied. The effects of adsorbent amount, contact time and pH on the adsorption of CTS-azacrown ethers were investigated. The extraction results showed that CTS-azacrown ethers had good sorption capacities for Cu(II) ions in the coexistence of Ni(II) ions.Öğe Investigation of synthesis of copolymers from the waste products of industrial oil refinement having adhesion properties and strength to the thermal destruction(SPRINGER/PLENUM PUBLISHERS, 2006) Yazicigil, Zafer; Ahmetli, Gulnare; Kara, Huseyin; Kocak, AhmetIn this study, the waste products of industrial vegetable oil refinement were transformed into the glycidyl ester for preventing the effects of them to the environment, the ways for evaluating them in polymer chemistry were investigated, copolymers having high adhesion property and strength to the thermal destruction were synthesized and the area of their usage was determined. For this reason, the waste product of sunflower oil refination as a vegetable oil in the industry; soap stock (SS) was converted to the unsaturated glycidyl esters by the interaction with epichlorohidrine in the alkaline medium. After that the copolymerization of synthesized unsaturated glycidyl esters and the other waste product of oil refinement fatty acid (FA) with styrene in the radicalic initiator medium were investigated and copolymers that have high strength to the thermal destruction and adhesion property were synthesized. From the results of TGA and DTA analysis, it was determined that synthesized copolymers have low loss of weight at high temperature. The structures of copolymers were fixed by spectral and chemical analysis methods.Öğe Kinetics of the copolymerization of alkylene oxides with glycidyl methacrylate(JOHN WILEY & SONS INC, 2007) Ahmetli, Gulnare; Kocak, Ahmet; Yazicigil, ZaferIn the present study, the kinetics of copolymerization reaction of propylene oxide (PO) and butylene oxide (BO) with glycidyl methacrylate (GNLA.) in the presence of BF3 center dot O(C2H5)(2) catalyst were investigated. The kinetic parameters and activation energy of the copolymerization reaction were calculated. The amounts of reacting PO, BO, and GMA during copolymerization were determined by chromatographic method, because the same copolymerization conditions were carried out for them. It was determined that the copolymerization rate of PO (r(0)) and BO (r(0)) was higher than that of GMA, but activation energy (E) of GMA was higher than that of PO and BO. The rate of reaction, the rate constant, and activation energy were calculated from the amount of copolymer obtained with respect to time. The structures of synthesized copolymers were determined by the spectral and chemical analysis methods.Öğe Novel liquid crystal trimers with a wide mesophase range(ELSEVIER SCIENCE BV, 2013) Malkondu, Sait; Kocak, AhmetNovel liquid crystal (LC) trimers with a flexible tris(2-aminoethyl)amine (TREN) core and cyanobiphenyl arms have been designed. These non-traditional mesogens form nematic mesophase over a broad temperature range depending on the alkyl chain length. Their chemical structures were confirmed by the combination of H-1 NMR, C-13 NMR, APT, COSY and FT-IR spectra. The mesophases were characterized by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). Thermogravimetric analysis showed that LC trimers are highly thermal stable both in the range of the mesophase and above the clearing point. (C) 2013 Elsevier B.V. All rights reserved.Öğe Synthesis and comparison of extraction properties of p-tert-butylcalix[n]arene nitrile derivatives for selected metals and dichromate anions(TAYLOR & FRANCIS INC, 2008) Kocak, Ahmet; Ceran, Saadet; Memon, Shahabuddin; Yilmaz, MustafaThe article describes the syntheses and extraction properties of two p-tert-butylcalix[6]arene nitrile derivatives (3 and 4). The trinitrile derivative 3 has been synthesized from 5,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41,42-hexahydroxy-calix[6]arene 1. The compound 1 was directly converted to its hexanitrile derivative (4). In these syntheses, it was considered to explore the role of nitrile sites in the extraction of various metal cations and HCr2O7-/Cr2O72- anions. The liquid-liquid extraction properties of 3 and 4 towards selected alkali/transition metal cations and HCr2O7-/Cr2O72- anions are reported. It has been observed that receptor 3 does not extract alkali/transition metal cations effectively, but shows affinity towards HCr2O7-/Cr2O72- anions at low pH. The compound 4 is an effective form for transferring Ni2+ selectively, while it shows poor transferring ability for HCr2O7-/Cr2O72- anions from an aqueous into a dichloromethane layer. It was observed that the cavity size of the calix[n]arenes and the cooperativity of the functionalities play important roles in two phase extraction systems.Öğe Synthesis and study of the oligo(ether-ester)s based on butylene oxide(JOHN WILEY & SONS INC, 2008) Ahmetli, Gulnare; Kocak, Ahmet; Soydal, UlkuUnsaturated oligo(ether-ester) was prepared by ring-opening polymerization of butylene oxide (BO) with glycidyl methacrylate (GMA) in the presence of cationic catalyst (BF3O)-O-center dot(C2H5)(2). The effects of mol ratio of the initial components, amount of catalyst, temperature, and reaction times on the copolymerization reaction were examined. Oligo(ether-ester) were achieved in highest yield of 82% after reaction times of 4 h at 0 degrees C. Synthesized copolymer was characterized using spectroscopic (H-1 NMR and IR) and chemical analysis methods. The thermal degradation and softing points of oligo(ether-ester)-styrene composites were studied. It is shown that crosslinking of the unsaturated oligo(ether-ester) with styrene takes place through the use of thermostable materials. (C) 2008 Wiley Periodicals, Inc.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 Synthetic access to new pyridone derivatives through the alkylation reactions of hydroxypyridines with Epoxides(TAYLOR & FRANCIS INC, 2007) Kocak, Ahmet; Kurbanli, Sultan; Malkondu, SaitGeneral methods for the preparation of a variety of pyridone and oxypyridine derivatives are described. 2-,3-,4-Hydroxy pyridine and 2-pyridinemethanol were alkylated with ethylene-, propylene-, and stryrene-oxide and epichlorohydrin in the presence of different Lewis acids as a catalyst. The best yield of 3a was achieved in the presence of CdI2/BF3 -OEt2. The corresponding pyridone derivatives (3a-d, 7a-d) were obtained from the reaction of 2- and 4-hydroxypyridine with oxiranes in good yields, whereas oxypyridine derivatives (5a-d, 9a,b) were obtained from reactions of 3-hydroxypyridine and 2-pyridinemethanol with oxiranes. Chlorohydrines (3d, 5d, 7d) were easily converted to corresponding epoxy derivatives (10, 11, 12) in basic medium; then amino alcohols (13-17) were obtained from the reaction of these epoxy derivatives with amines.
