Yazar "Demirel, Nadir" seçeneğine göre listele

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  • Küçük Resim
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    Benzen birimleri içeren kiral N, N'-disubstitue 18-crown-6-eter türevlerinin sentezi
    (2016) Demirel, Nadir; Hoşgören, Halil
    Crown eterlerin en önemli özellikleri, değişik bir çok metal, ammonyum ve diazonyum katyonları ile kompleks oluşturabilmeleridir. îlk makrosiklik bileşik Pedersen tarafından sentezlenmiş ve o günden sonra kimyacılar bu bileşiklerin kiral türevlerinin enzimatik ve diğer reaksiyonlarda kiral tanıma için bir model oluşturduğunu farkettiler. îlk sentetik kiral makrosiklik bileşik 1 972 yılında Wudl ve Gaeta tarfından Z-prolin kullanılarak sentezlenmiştir. Sentezlenen kiral crown eterler protonlanmış amin ve amin bileşiklerinin moleküler tanınmasında ve ayrıca değişik reaksiyonlarda kiral katalizör olarak kullanılmıştır. Kiral amin bileşiklerini ayırmak için kullanılan aminoasit veya türevleri, siklodekstrinler, karbonhidratlar içinde kiral crown eterler durağan faz olarak en etkili bileşiklerdir. Crown eterlerde kiral merkez yan kollar üzerinde bulunduğunda Z-amino asitleri, amino asit K+ tuzlarım ve dipeptit K+ karboksilatları kloroform membranından seçici bir şekilde taşıdıkları gösterilmiştir.
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    Öğe
    Benzen birimleri içeren N1N1-disübstitüe 18-crown-6 eter türevlerinin hazırlanması
    (Dicle Üniversitesi, Fen Bilimleri Enstitüsü, 1999) Demirel, Nadir; Hoşgören, Halil
    Alkali metaller ve toprak alkali metallerin sıvı-sıvı ekstraksiyonunda, moleküller tanıma proseslerinde sentetik alıcılar ve faz transfer katalizörü olarak yaygınca kullanılan lipofilik karakteri arttırılmış benzen birimleri içeren crown eter türevlerinin hazırlanması amaçlanmıştır. Aza crown eterler oksijenli crown bileşiklerine göre ammonyum tuzları ve geçiş metalleri ile daha iyi kompleks oluşturabilmektedir. Aynı zaamanda crown bileşiklerine benzen sübstitüsyonu yaparak host bileşiğinin organik çözücüdeki çözünürlüğü arttırılmış ve aromatik yapısından dolayı kompleks oluşumu UV spektrometresi ile takip edebilme olanağı sağlanmıştır. Bu nedenle lipofilik karakteri arttırılmış bir seri monobenzo ve dibenzodiaza crown eter türevleri hazırlanmıştır.
  • Küçük Resim
    Öğe
    DNA binding and cleavage activity of three new copper (II) complexes of chiral N-salicyl-?-amino alcohol schiff bases
    (Sociedad Quimica de Mexico A.C., 2018) Tunç, Turgay; Demirel, Nadir; Emir, Mahmut; Günel, Aslıhan; Çolak, Mehmet; Karacan, Nurcan
    Three new copper(II) complexes (1-3) with general formula [Cu(HL)CH 3 COO] of N-salicyl-β-amino alcohol Schiff bases containing, (S)-(+)-phenyl glycinol, (1S, 2R)-2-amino-1, 2-diphenylethanol and 1, 1, 3-triphenyl-(R)-(+)-2-amino propanol, were synthesized. Their structures were characterized by FTIR, LCMS, magnetic moment, molar conductance and elemental analysis data. DFT calculations proposed distorted square planar geometries for the complexes. The calculated IR spectra are in good agreement with the experimental IR spectra, confirming the proposed structures. Their interactions with calf thymus DNA were investigated and their binding constants K b were found. Gel electrophoresis reveals that all complexes display significant nuclease activity against supercoiled pentry/d-topo plasmid DNA.
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    The effect of benzo substitution on complexation of diaza 18-crown-6 ethers derivatives with NaClO4 (vol 52, pg 51, 2005)
    (Springer, 2006) Koeylue, M. Zafer; Demirel, Nadir; Polat, F. Doganel; Yilmaz, Ali; Hosgoeren, Halil; Balci, Metin
    [Abstract Not Available]
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    Enantioselective nitroaldol (Henry) reaction catalyzed by chiral Schiff-base ligands
    (Pergamon-Elsevier Science Ltd, 2008) Colak, Mehmet; Demirel, Nadir
    Chiral Schiff-bases 2, 3, 4 and 5 were designed for the enantioselective nitroaldol (Henry) reaction. The highest enantioselectivity was observed for ligand 4 (82% ee) when CH2Cl2 was used as a solvent. (C) 2008 Elsevier Ltd. All rights reserved.
  • Küçük Resim
    Öğe
    Enantioselective transport and liquid-liquid extraction of amino acids as their potassium and sodium salts by optically active diaza-18-crown-6 ethers
    (Wiley, 2004) Demirel, Nadir; Bulut, Yasemin; Hoşgören, Halil; 0000-0002-8571-5552
    Complexation of amino acids as their sodium and potassium salts by optically active diaza crown ethers has been investigated in transport across bulk liquid membranes containing the carriers and in extraction experiments. The observed enantio selectivity was achieved by (noncovalent) steric and repulsive interactions between the side arm of the crown ether and functional group(s) of the amino acids. The highest enantio selectivity was observed in the case of tryptophan. (C) 2004 Wiley-Liss, Inc.
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    Facile synthesis of mono and dibenzo N, N-disubstituted diaza 18-crown-6 derivatives
    (Hetero Corporation, 2001) Topal, Giray; Demirel, Nadir; Toğrul, Mahmut; Turgut, Yılmaz; Hoşgören, Halil; 0000-0002-7056-3912; 0000-0002-8571-5552; 0009-0000-3823-0467
    This study represents a facile synthesis of building blocks (1-3) of crown ethers and amine precoursers (4a-d). The study also involves synthesis of mono and dibenzo N,N'-disubstituted diaza 18-crown-6 derivatives with high yield without chromatographic purification and high vacuum distillation. The complex ability of host the ethers was evaluated in terms of structural modification.
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    Kiral monoza ve diaza taç eter sentezi ve enantiyoselektif Michael katılmasında katalizör olarak kullanılması
    (2001) Turgut, Yılmaz; Demirel, Nadir; Topal, Giray; Toğrul, Mahmut; Özbey, Süheyla; Hoşgören, Halil
    [Abstract Not Available]
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    Lysine-based two-component organogelator: Naproxen carrier soft material
    (John Wiley and Sons Inc, 2023) Çolak, Mehmet; Kaya, Gülşen; Hayaloğlu, Ali Adnan; Demirel, Nadir; Hoşgören, Halil
    We demonstrated that Nϵ -alkanoyl-L-lysine ethyl ester/N-alkanoyl-L-phenylalaninate gelling agents were constructed as a two-component gelling strategy and applied as drug carriers in friendly solvents commonly used. Our designs are expected to have an edge in contrast to the other lipid-based systems due to cheap raw materials, reducing the required amount of carrier, low molecular weight, ease of loading, simple dose adjustability, skin spreadability, and improved drug retention times. It could be loaded with Naproxen (Npx) with a high loading efficiency (up to 100 % as a percentage of gelator) without gel disruption. A complementary in vitro drug release study under specific pH was conducted and performed at different drug and gelator concentrations. These results reveal that the release of Npx from the supramolecular organogels was significantly retarded with increasing organogelator engagement from 0.46 % to 0.92 %, the initial release rate considerably reduced, from 18.75 % to 7.21 %, respectively; that is release rate shows a 2.6-fold decrease; this result showed that the gelator concentration could control drug release. whereas the increasing Npx concentration enhanced it. Altogether, this work produces valuable outcomes, which may be relevant to the pharmaceutical industry, suggesting that new platforms may deliver NSAID (non-steroidal anti-inflammotory drug) molecules.
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    Polymer supported 5,10,15,20-tetrakis(phenoxy acetic acid)porphyrin derivative for separation and preconcentration of d- and f-electron metals
    (Springer Wien, 2008) Seyhan, Serap; Merdivan, Melek; Demirel, Nadir; Hosgoren, Halil
    5,10,15,20-tetrakis(phenoxy acetic acid) porphyrin (PAAP) was covalently linked to Merrifield chloromethylated resin. Characterization of PAAP and the modified polymeric matrix were performed by H-1 NMR, FTIR and elemental analysis. The sorbent was used for the separation and enrichment of the d-electron metals (Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) at pH 6-8 and of the f-electron metals U(VI) and Th(IV) at pH 4-5. The metals ions were preconcentrated with a concentration factor range of 115-215 and then determined by flame atomic absorption spectrometry or visible spectrophotometry using Arsenazo(III). The retained metals were eluted with 2.0 mol L-1 HNO3 in the case of the d-electron metals and 0.1/0.25mol L-1 HCl in the case of the f-electron metals. The procedure was validated by analyzing the NIST standard reference material 2709 (San Joaquin Soil).
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    Solid phase extractive preconcentration of trace metals using p-tert-butylcalix[4]arene-1,2-crown-4-anchored chloromethylated polymeric resin beads
    (Elsevier, 2007) Seyhan, Serap; Colak, Mehmet; Merdivan, Melek; Demirel, Nadir
    5,11,17,23-Tetrakis(1,1-dimethylethyl)-25,26-dihydroxy-27,28-crown-4-calix[4]arene in the cone conformation was synthesized. This p-tertbutylcalix[4]arene-1,2-crown-4 compound was then anchored with Merrifield chloromethylated resin beads. The modified polymeric resin was characterized by H-1 NMR, FT-IR and elemental analysis and used successfully for the separation and preconcentration of Cu(II), Cd(II), Co(II), Ni(II) and Zn(II) prior to their determination by FAAS. Effective extraction conditions were optimized in both batch and column methods. The resin exhibits good separating ability with maximum between pH 6.0-7.0 for Cu(II), pH 6.0 for Cd(II), pH 5.0 for Co(II), pH 4.0-4.5 for Ni(II), and pH 4.5 for Zn(H). The elution studies were carried out with 0.5 mol L-1 HCL for Cu(II), Co(II) and Co(II), 1.0 mol L-1 HCl for Cd(II) and Zn(II). The sorption capacity, preconcentration factor and distribution coefficient of each metal ion were determined. The detection limits were 1.10, 1.25, 1.83, 1.68 and 2.01 mu g L-1 for Cu(II), Cd(II), Co(II), Ni(II) and Zn(II). The influence of several ions on the resin performance was also investigated. The validity of the proposed method was checked for these metal ions in NIST standard reference material 2709 (San Joaquin Soil) and 2711 (Montana Soil). (c) 2006 Elsevier B.V. All rights reserved.
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    Solvent-free synthesis of chiral Schiff-base ligands based on ferrocene under microwave irradiation and application to enantioselective nitroaldol (Henry) reaction
    (Wiley, 2011) Öztürk, Gülşen; Çolak, Mehmet; Demirel, Nadir; 0000-0002-3774-2652; 0000-0002-8571-5552
    Chiral Schiff-bases 3a-f based on ferrocene were designed and synthesized using solvent-free methods by mixing ferrocene carbaldehyde 1 with amino alcohols and amines 2a-f under microwave irradiation and classical method for the enantioselective nitroaldol (Henry) reaction. The Schiff-bases were obtained in shorter reaction times and improved yield under microwave irradiation method over classical method. The highest enantioselectivity was observed in ligand 3e (95% ee) when CH2Cl2 was used as solvent. Chirality 23: 374-378, 2011. (c) 2011 Wiley-Liss, Inc.
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    Synthesis of novel chiral Schiff-base ligands and their application in asymmetric nitro aldol (Henry) reaction
    (Pergamon-Elsevier Science Ltd, 2007) Colak, Mehmet; Aral, Tarik; Hosgoeren, Halil; Demirel, Nadir
    Chiral Schiff-bases prepared from chiral amino alcohols catalyze the enantio selective Henry (nitro aldol) reaction between nitromethane and p-nitrobenzaldehyde in the presence of Cu(OTf)(2) and Zn(OTf)(2). Zn(OTf)(2) promoted the reaction yield, while Cu(OTf)(2) promoted the enantiomeric excess. The highest enantioselectivities were observed with ligand 3 (44% ee) and ligand 5 (47% ee). (C) 2007 Elsevier Ltd. All rights reserved.
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    Two-component organogelators: combination of N?-alkanoyl-L-lysine with various N-alkanoyl-L-amino acids: additional level of hierarchical control
    (Taylor & Francis Inc, 2018) Colak, Mehmet; Baris, Deniz; Evcil, Murat; Demirel, Nadir; Hosgoeren, Halil
    Synthesis of two-component organogelation system was performed very easy and concise manner from N-epsilon-palmitoyl-L-lysine ethyl ester and N-epsilon-miristoyl-L-lysine ethyl ester in which they were used as base component and N-lauroyl-L-amino acids (amino acids:, alanine, leucine and phenylalanine as acid components.). And their organogelation properties were examined in different pharmaceutical fluids such as liquid paraffin, fatty acid ethyl, and isopropyl esters. In this way, gelation efficiency was ascertained variations of alkanoyl moieties and combination of different amino acids in the gelator structures. Characterization of gelators was performed via thermal measurement such as Tg and gel-sol enthalpy change; SEM and FTIR as optical methods.
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    Use of o-phenylene dioxydiacetic acid impregnated in Amberlite XAD resin for separation and preconcentration of uranium(VI) and thorium(IV)
    (Elsevier Science Bv, 2008) Seyhan, Serap; Merdivan, Melek; Demirel, Nadir
    The impregnation of o-phenylene dioxydiacetic acid (OPDA) into a polymeric matrix, Amberlite XAD-2000, is reported and was characterized by infrared spectroscopy. The amount of attached OPDA to the polymer resin was found to be 1.77 mmol g(-1) resin. The resin was used for the sorption of U(VI) and Th(IV) from aqueous solution. This sorbent was capable of preconcentrating U(VI) and Th(IV) from weakly acidic or neutral solution. The retained metals were eluted sequentially using 0.25 mol L-1 HCl for U(VI) and I mol L-1 HCl for Th(IV) and determined spectrophotometrically using arsenazo-(III). The capacity of the resin for U(VI) and Th(IV) was found to be 0.121 and 0.113 mmol g(-1), respectively. The impregnated resin exhibits a high chemical stability, reusability and fast equilibration. The method was used for the determination of U(VI) and Th(IV) in synthetic samples and rock samples. (C) 2007 Elsevier B.V. All rights reserved.