Yazar "Bingöl, Haluk" seçeneğine göre listele
Listeleniyor 1 - 20 / 29
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Amperometric Glucose Biosensor Based on Glucose Oxidase, 1,10-Phenanthroline-5,6-dione and Carbon Nanotubes(ELECTROCHEMICAL SOC INC, 2014) Zor, Erhan; Öztekin, Yasemin; Ramanaviciene, Almira; Anusevicius, Zilvinas; Bingöl, Haluk; Barkauskas, Jurgis; Ersöz, MustafaA biosensor for glucose determination was fabricated by the immobilization of glucose oxidase (GOx) on carbon nanotubes (CNTs) and/or 1,10-phenanthroline-5,6-dione (PD) modified graphite rod electrodes (GOx/PD/CNTs/GR) and its amperometric response toward glucose was investigated under aerobic and anaerobic conditions. The sensitivity of the GOx/PD/CNTs/GR electrode was found to be higher compared to that of a PD-modified GR electrode without CNTs (GOx/PD/GR), implying that CNTs play an important role in the facilitation of electron transfer between the redox active site of GOx and the electrode surface. The GOx/PD/CNTs/GR biosensor exhibited a linear dependency on substrate concentration in a range from 0.0 until 50.0 mM of glucose with oxygen present and from 0.0 until 62.5 mM of glucose in the absence of oxygen. With oxygen present, the limit of detection (LOD) values were determined to be 5.4 and 8.0 mM, and the limit of quantitation values (LOQ) were calculated as 16.2 and 24 mM for GOx/PD/GR and GOx/PD/CNTs/GR, respectively. In the absence of oxygen, the LOD values were calculated as 4.2 and 10.7 mM, and the LOQ values were calculated as 12.6 and 32.1 mM for GOx/PD/GR and GOx/PD/CNTs/GR, respectively. When examining the interference effect of uric acid for GOx/PD/GR and GOx/PD/CNTs/GR electrodes, no significant changes in the amperometric response of the modified electrodes were observed up to 100.0 mM of uric acid. (C) 2014 The Electrochemical Society. All rights reserved.Öğe Bazı geçiş metal iyonlarının sıvı/sıvı arayüzden tiyosemikarbazon yardımlı transferlerinin voltametrik metotla incelenmesi(Selçuk Üniversitesi Fen Bilimleri Enstitüsü, 2007-03-24) Bingöl, Haluk; Atalay, TevfikBu çalışmada, polarizlenmiş su/1,2-dikloroetan (1,2-DCE) arayüzünden Cu(II), Cd(II), Co(II), Ni(II), Pb(II), Zn(II) ve Hg(II) gibi geçiş metal iyonlarının çeşitli tiyosemikarbazon türevleri ile yardımlı transferleri, dönüşümlü voltametri kullanılarak çalışıldı. Tiyosemikarbazon türevi olarak, 4-morfolinoasetofenon-4- fenil-tiyosemikarbazon (MAPPT), 9-Etil-3-karbazolkarboksaldehit-tiyosemikarbazon (ECCAT) ve 9-etil-3-karbazolkarboksaldehit-4-fenil-tiyosemikarbazon (ECCAPT) kullanıldığı zaman, voltametrik analiz için uygun sonuçlar gözlendi. ECCAT ve ECCAPT ligandları ile Cd(II) ve Pb(II) iyonlarının yardımlı transferleri analiz edilebilirken, MAPPT ligandı ile sadece Cd(II) iyonunun yardımlı transferi analiz edilebildi. Tersinir veya yarı tersinir transfer karakterine sahip ligand ve metal iyonlarının stokiyometrilerini, toplam oluşum sabitlerini ve transfer mekanizmalarını belirlemek için, Galvani transfer potansiyelinin ligand konsantrasyonuna bağlılığı kullanıldı. Su/1,2-DCE arayüzünde, dağılma katsayıları belirlenen hidrofobik tiyosemikarbazonların yardımlı iyon transferlerine ait dönüşümlü voltametri deneyleri, TIC mekanizmasıyla arayüzde meydana gelen ve 1:3 (metal:ligand) stokiyometrisine sahip komplekslerin oluştuğunu göstermiştir. [Pb(ECCAT)3]2+, [Cd(ECCAT)3]2+, [Pb(ECCAPT)3]2+, [Cd(ECCAPT)3]2+ [Cd(MAPPT)3]2+ ve komplekslerinin toplam oluşum sabitleri logaritmik olarak ( log β3 ), sırasıyla, o (14,03±0,09), (15,44±0,07), (13,44±0,08), (13,72±0,09) ve (15,46±0,11) olarak hesaplanmıştır. Diğer metal iyonları kullanıldığı zaman, bazıları için deney şartlarında herhangi bir transfer piki görülmezken, bazıları için de dönüşümlü voltametri analizi yeteri kadar değerlendirilemeyen farklı yapıdaki pikler elde edilmiştir.Öğe Bazı tiyosemikarbazon-geçiş metalleri kompleksleşme reaksiyonlarının kinetiği(Selçuk Üniversitesi, Fen Bilimleri Enstitüsü, 2002) Bingöl, Haluk; Atalay, TevfikBu çalışmada, Co(II) ile 2-Benzoilpridin-4-fenil-3-tiyosemikarbazon (BPPT) ve Cu(II) ile 9-Etil-3-karbazolkarboksaldehit-tiyosemikarbazon (ECCAT) arasında gerçekleşen kompleksleşme reaksiyonlarının kinetiği spektrofometrik metotla incelendi. Kullanılan BPPT ligandı literatürden farklı olarak yeni bir metotla, ECCAT ligandı ise ilk defa sentezlendi. Her iki ligand-metal kompleksinin de stokiyometrik oranları 1:2 olarak tespit edildi. Co(II)-BPPT ve Cu(II)-ECCAT komplekslerinin maksimum absorpsiyon yaptıkları dalga boyları sırasıyla 421 ve 393 nm olarak bulundu. Daha sonra belirlenen bu optimum şartlarda reaksiyon hızlarına sıcaklığın etkisi incelenerek Arrhenius ve Eyring denklemlerinden kinetik ve aktivasyon parametreleri hesaplandı (k, A, Ea, ΔH#, ΔS#, ΔG#). Kompleksleşme reaksiyonları için hız denklemleri ve mekanizmalar önerildi.Öğe Discriminative sensing of DOPA enantiomers by cyclodextrin anchored graphene nanohybrids(ELSEVIER SCIENCE BV, 2017) Ateş, Salih; Zor, Erhan; Akın, İlker; Bingöl, Haluk; Alpaydın, Sabri; Akgemci, Emine GülerDiscriminative sensing of chiral species with a convenient and robust system is a challenge in chemistry, pharmaceutics and particularly in biomedical science. Advanced nanohybrid materials for discrimination of these biologically active molecules can be developed by combination of individual obvious advantages of different molecular scaffolds. Herein, we report on the comparison of the performance of cyclodextrin functionalized graphene derivatives (x-CD/rGO, x: alpha-, beta-, gamma-) for discrimination of DOPA enantiomers. Within this respect, electrochemical measurements were conducted and the experimental results were compared to molecular docking method. Thanks to cavity size of g-CD and the unique properties of graphene, rGO/gamma-CD nanohybrid is capable of selective recognition of DOPA enantiomers. Limit of detection (LOD) value and sensitivity were determined as 15.9 mu M and 0.2525 mu A mu M-1 for D- DOPA, and 14.9 mu M and 0.6894 mu A mu M-1 for L-DOPA. (C) 2017 Elsevier B.V. All rights reserved.Öğe Effect of N(4)-phenyl group on the lipophilicity scale of 2-benzoylpyridine thiosemicarbazone based on the ion transfer across the liquid/liquid interface(2006) Akgemci, Emine Güler; Bingöl, Haluk; Özçelik M.; Atalay T.; Ersöz, Mustafa[Abstract not Available]Öğe Effect of N(4)-substituent groups on transfer of 2-benzoylpyridine thiosemicarbazone derivates at the water/1,2-dichloroethane interface(PERGAMON-ELSEVIER SCIENCE LTD, 2007) Akgemci, Emine Güler; Bingöl, Haluk; Atalay, T.; Ersöz, A.Dependent on the pH of the aqueous phase, the transfer of protonated forms of 2-benzoylpyridine N(4)-phenyl thiosemicarbazone (BPPT) (which has antimicrobial, antifungal and anticytotoxic activities) and 2-benzoylpyridine N(4)-ethyl thiosemicarbazone (BPET) across water/1,2dichloroethane (1,2-DCE) interface has been studied by cyclic voltarnmetry. The protonation constants of the ligands (pK(a1)(w) and pK(a2)(w)) were a I a2 determined by spectrophotometry. The standard partition coefficients (log P-i(0)) and the standard Gibbs energies of ionic (cationic) species of ligands (Delta G(tr,i)(0,w -> o)) were calculated from the standard transfer potentials (Delta(w)(o)phi(0)(i)). The standard Gibbs energies of their transfer (Delta G(tr,i)(0,w -> o)) and partition coefficients of neutral species (log P-N) were determined by shake-flask method. These thermodynamic parameters were evaluated as a quantitative and qualitative measure of the lipophilicities of two compounds. The differences between the partition coefficients of cationic and neutral form of compounds [diff(log P1+-N)] were interpreted by results obtained from voltammetric data. Effect of N(4)-phenyl and ethyl groups for transfer of 2-benzoylpyridine thiosemicarbazone derivatives at macro-liquid/liquid interface was investigated. The antimicrobial activity of BPET was tested against four types of bacteria and found to be active against Staphlylococcus aureus. (c) 2007 Elsevier Ltd. All rights reserved.Öğe An electrochemical and computational study for discrimination of D- and L-cystine by reduced graphene oxide/beta-cyclodextrin(ROYAL SOC CHEMISTRY, 2015) Zor, Erhan; Bingöl, Haluk; Ramanaviciene, Almira; Ramanavicius, Arunas; Ersöz, MustafaHere, we report a novel enantioselective electrochemical biosensor for the discrimination of cystine enantiomers (D- and L-cystine) using a chiral interface for the specific recognition of D- and L-cystine. The biosensor is based on reduced graphene oxide modified by beta-cyclodextrin (rGO/beta-CD) at the GCE surface. During the preparation of rGO/beta-CD/GCE, the modified electrode surfaces were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The electrochemical behaviours of the D- and L-cystine were investigated using the rGO/beta-CD/GCE by CV and compared to bare GCE. A clear separation between the oxidation peak potentials of D- and L-cystine was observed at 1.32 and 1.42 V, respectively. The electrochemical discrimination performance of the fabricated chiral sensor was also examined by differential pulse voltammetry (DPV) in a mixed solution of D- and L-cystine. In addition, the DPV technique was used for the determination of D- and L-cystine at low concentration values in the range of 1.0-10.0 mM. To investigate the amperometric response of rGO/beta-CD/GCE towards D- and L-cystine, the chronoamperometry technique was used in the concentration range of 10.0-100.0 mu M. The interactions of the enantiomers with rGO/beta-CD were modelled by molecular docking using AutoDock Vina, and the interaction energies were predicted to be -4.8 and -5.3 kcal mol(-1) for D- and L-cystine, respectively. The corresponding values of binding constants were calculated to be 3.32 x 10(3) and 7.71 x 10(3) M-1, respectively. The experimental and molecular docking results indicate that the rGO/beta-CD/GCE has a different affinity for each enantiomer.Öğe An electrochemical biosensor based on human serum albumin/graphene oxide/3-aminopropyltriethoxysilane modified ITO electrode for the enantioselective discrimination of D- and L-tryptophan(ELSEVIER ADVANCED TECHNOLOGY, 2013) Zor, Erhan; Patır, İmren Hatay; Bingöl, Haluk; Ersöz, MustafaA new electrochemical biosensor based on the human serum albumin/graphene oxide/3-aminopropyl-triethoxysilane modified indium tin oxide electrode (ITO/APTES/GO/HSA) has been developed for the discrimination of tryptophan (Trp) enantiomers. The electrode has been characterized by scanning electron microscopy (SEM) and electrochemical techniques. The electrochemical behaviors of the enantiomeric pairs (D- and L-Trp) at the ITO/APTES/GO/HSA electrode have been investigated by cyclic voltammetry in the concentration range of 0.10-1.0 mM. A clear separation between the oxidation peak potentials of D- and L-Trp, at 0.86 and 1.26 V, respectively, has suggested that the ITO/APTES/GO/HSA electrode can be used as an electrochemical biosensor for the discrimination of Trp enantiomers. In order to find the percentage of an enantiomeric form of tryptophan in a mixture, the ITO/APTES/GO/HSA electrode is used for the simultaneous detection of D- and L-Trp which showed that the percentage of one enantiomeric form can be easily measured in the presence of the other. (c) 2012 Elsevier B.V. All rights reserved.Öğe Electrochemical investigation of heavy metal ion transfer across the water/1,2-dichloroethane interface assisted by 9-ethyl-3-carbazolecarboxaldehyde-thiosemicarbazone(WILEY-V C H VERLAG GMBH, 2007) Bingöl, Haluk; Akgemci, Emine Güler; Ersöz, Mustafa; Atalay, TevfikThe transfer of heavy metal ions across the polarized water/1,2-dichloroethane (1,2-DCE) interface assisted by 9ethyl-3-carbazolecarboxaldehyde-thiosemicarbazone (ECCAT) in the 1,2-DCE phase has been studied by cyclic voltammetry. Voltammetric waves of Pb(II) and Cd(II) ions were reversible and quasi-reversible, respectively, whereas that of Hg(II) and Zn(II) ion were irreversible. The voltammogram of Cu(II) ion showed a two-step wave, however the nature of the transfer could not be satisfactorily evaluated by analyzing the cyclic voltammetric data. When Ni(II) and Co(II) was used no peak was visible under the experimental conditions used in this study. The dependence of the half-wave potentials of Pb(II) and Cd(II) ions on the ligand concentration reveals that their ion-transfer is assisted by the formation of 1:3 metal-ECCAT complex in 1,2-DCE. The over-all association constants of [Pb(ECCAT)(3)](2+) and [Cd(ECCAT)(3)](2+) complexes in DCE-phase have been determined to be log beta(3)(0)= 14.03 and log beta(0)(3) = 15.44, respectively.Öğe Facilitated Transfer of Alkali and Alkaline-Earth Metal Ions by a Calix[4]arene Derivative Across Water/1,2-Dichloroethane Microinterface: Amperometric Detection of Ca2+(Wiley-V C H Verlag Gmbh, 2010) Bingöl, Haluk; Kaykal, Ferhat; Akgemci, Emine Güler; Sırıt, AbdulkadirThe host-guest complexation reactions between 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarbonylmethoxy-26,28-dimethoxy calix[4] arene ( BDDC4) and alkali and alkaline-earth metal ions were investigated by facilitated ion transfer processes across water/1,2-dichloroethane microinterface by using steady-state cyclic voltammetry and differential pulse voltammetry. The obtained facilitated transfers for Li+, Na+, K+, Rb+ and Ca2+ were evaluated under the different experimental conditions, at the excess concentrations of metal ions with respect to BDDC4 and vice versa. The association constants having 1 : 1 stoichiometry for Li+, Na+, K+ and Rb+ in 1,2-DCE were determined. Also, we demonstrated that BDDC4 can play an important role for the development of highly selective chemical sensor for Ca2+ among alkaline-metal ions in the concentration range of 0.1-1.0 mM in aqueous solution.Öğe Facilitated transfer of alkali metal ions by a tetraester derivative of thiacalix[4]arene at the liquid-liquid interface(WILEY-V C H VERLAG GMBH, 2008) Akgemci, Emine Güler; Bingöl, Haluk; Ersöz, Mustafa; Stibor, IvanThe facilitated transfer of alkali metal ions (Na+, K+, Rb+, and Cs+) by 25,26,27,28-tetraetboxycarbonylmethoxy-thiacalix[4]arene across the water/1,2-dichloroethane interface was investigated by cyclic voltammetry. The dependence of the half-wave transfer potential on the metal and ligand concentrations was used to formulate the stoichiometric ratio and to evaluate the association constants of the complexes formed between ionophore and metal ions. While the facilitated transfer of Li+ ion was not observed across the water/1,2-dichloroethane interface, the facilitated transfers were observed by formation of 1: 1 (metal: ionophore) complex for Na+, K+, and Rb+ ions except for Cs+ ion. In the case of Cs+ a 1:2 (metal: ionophore) complex was obtained from its special electrochemical response to the variation of ligand concentrations in the organic phase. The logarithms of the complex association constants, for facilitated transfer of Na+, K+, Rb+, and Cs+, were estimated as 6.52, 7.75, 7.91 (log beta(1)degrees), and 8.36 (log V), respectively.Öğe Graphene Quantum Dots-based Photoluminescent Sensor: A Multifunctional Composite for Pesticide Detection(AMER CHEMICAL SOC, 2015) Zor, Erhan; Morales-Narvaez, Eden; Zamora-Galvez, Alejandro; Bingöl, Haluk; Ersöz, Mustafa; Merkoci, ArbenDue to their size and difficulty to obtain, cost/effective biological or synthetic receptors (e.g., antibodies or aptamers, respectively), organic toxic compounds (e.g., less than 1 kDa) are generally challenging to detect using simple platforms such as biosensors. This study reports on the synthesis and characterization of a novel multifunctional composite material, magnetic silica beads/graphene quantum dots/molecularly imprinted polypyrrole (mSGP). mSGP is engineered to specifically and effectively capture and signal small molecules due to the synergy among chemical, magnetic, and optical properties combined with molecular imprinting of tributyltin (291 Da), a hazardous compound, selected as a model analyte. Magnetic and selective properties of the mSGP composite can be exploited to capture and preconcentrate the analyte onto its surface, and its photoluminescent graphene quantum dots, which are quenched upon analyte recognition, are used to interrogate the presence of the contaminant. This multifunctional material enables a rapid, simple and sensitive platform for small molecule detection, even in complex mediums such as seawater, without any sample treatment.Öğe Graphene-based hybrid for enantioselective sensing applications(ELSEVIER ADVANCED TECHNOLOGY, 2017) Zor, Erhan; Morales-Narvaez, Eden; Alpaydın, Sabri; Bingöl, Haluk; Ersöz, Mustafa; Merkoci, ArbenChirality is a major field of research of chemical biology and is essential in pharmacology. Accordingly, approaches for distinguishing between different chiral forms of a compound are of great interest. We report on an efficient and generic enantioselective sensor that is achieved by coupling reduced graphene oxide with gamma-cyclodextrin (rGO/gamma-CD). The enantioselective sensing capability of the resulting structure was operated in both electrical and optical mode for of tryptophan enantiomers (D-/L-Trp). In this sense, voltammetric and photoluminescence measurements were conducted and the experimental results were compared to molecular docking method. We gain insight into the occurring recognition mechanism with selectivity toward D- and L-Trp as shown in voltammetric, photoluminescence and molecular docking responses. As an enantioselective solid phase on an electrochemical transducer, thanks to the different dimensional interaction of enantiomers with hybrid material, a discrepancy occurs in the Gibbs free energy leading to a difference in oxidation peak potential as observed in electrochemical measurements. The optical sensing principle is based on the energy transfer phenomenon that occurs between photo excited D-/L-Trp enantiomers and rGO/gamma-CD giving rise to an enantioselective photoluminescence quenching due to the tendency of chiral enantiomers to form complexes with gamma-CD in different molecular orientations as demonstrated by molecular docking studies. The approach, which is the first demonstration of applicability of molecular docking to show both enantioselective electrochemical and photoluminescence quenching capabilities of a graphene-related hybrid material, is truly new and may have broad interest in combination of experimental and computational methods for enantiosensing of chiral molecules. (C) 2016 Elsevier B.V. All rights reserved.Öğe Green synthesis of reduced graphene oxide/nanopolypyrrole composite: characterization and H2O2 determination in urine(ROYAL SOC CHEMISTRY, 2014) Zor, Erhan; Sağlam, Muhammed Esad; Akın, İlker; Saf, Ahmet Özgür; Bingöl, Haluk; Ersöz, MustafaHere we report on a novel, simple and eco-friendly approach for the fabrication of a reduced Graphene Oxide/nanopolypyrrole (rGO/nPPy) composite material and its electrochemical performance for detection of hydrogen peroxide on a glassy carbon electrode. The characterization of the as-prepared rGO/nPPy composite was investigated by Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet-visible spectroscopy, scanning electron microscopy, contact angle measurement, cyclic voltammetry and electrochemical impedance spectroscopy. Cyclic voltammetry, differential pulse voltammetry and chronoamperometry techniques were used to investigate and optimize the performance of the developed electrochemical biosensor. The proposed biosensor showed excellent analytical response towards the quantification of H2O2 at pH 7.40. Under the optimized conditions, the biosensor shows a linear response range from 1.0 x 10(-7) to 4.0 x 10(-6) M concentrations of H2O2. The limit of detection was determined to be 34 nM. Reproducibility, sensitivity, stability and anti-interference capability of the fabricated biosensor for the detection of H2O2 were examined. The biological relevance of the developed electrochemical biosensor was further studied by the determination of H2O2 in urine samples. The real sample analysis of H2O2 was achieved before and after drinking coffee in urine samples. The successful and sensitive determination of H2O2 urine samples indicates that the proposed electrochemical biosensor can be applied to the quantification analysis of H2O2 in real samples.Öğe Green Synthesis of Reduced Graphene Oxide/Polyaniline Composite and Its Application for Salt Rejection by Polysulfone-Based Composite Membranes(AMER CHEMICAL SOC, 2014) Akın, İlker; Zor, Erhan; Bingöl, Haluk; Ersöz, MustafaIn this study, a novel, simple, and eco-friendly enzymatic-reaction-based approach to produce reduced graphene oxide/polyaniline (rGO/PANI) composite material was proposed. Glucose oxidase (GOx) was used as an effective catalyst producing hydrogen peroxide, in the presence of glucose, for the oxidative polymerization of aniline under ambient conditions. The prepared rGO/PANI composite was dispersed in polysulfone (PSf), and the mixed membranes were prepared by the phase inversion polymerization method. The morphology of membranes was investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle (CA) techniques. The performance of membranes was studied in terms of salt rejection and pure water flux. The incorporation of rGO into the membrane matrix led to hydrophobic membrane surface with the enhanced macro-voids. On the contrary, the contact angle data revealed that the rGO/PANI-incorporated membrane surface is partly hydrophilic due to the PANI fibers in membrane, whereas SEM images showed the enhanced macro-voids. Membranes exhibited an improved salt rejection after rGO/PANI doping. The rGO/PANI-modified membrane loading exhibited a maximum of 82% NaCl rejection at an applied pressure of 10 bar. In addition, the results showed that the PSf-rGO/PANI composite membrane had the highest mean porosity and water flux.Öğe Interfacial Transfer of Cd2+ Assisted by 4 '-Morpholino-Acetophenone-4-Phenyl-3-Thiosemicarbazone Across the Water/1,2-Dichloroethane Interface(Versita, 2010) Bingöl, Haluk; Atalay, TevfikThe assisted transfer of heavy metal ions by interfacial complexation with 4'-morpholinoacetophenone-4-phenyl-3-thiosemicarbazone (MAPPT) at the interface between two immiscible electrolyte solutions (ITIES) was studied by cyclic voltammetry. The voltammograms obtained across the water/1,2-dichloroethane interface using the MAPPT ligand in the organic phase shows that the assisted metal ion transfers have different nature for different ions. The quasi-reversible voltammetric peak of the Cd2+ ion was obtained and is discussed in detail. The dependence of the half-wave transfer potential on MAPPT concentration showed that the equilibrium is effectively displaced towards a 1:3 (metal:ligand) stoichiometry with an association constant of log beta(0) = 15.46 (+/- 0.11) for the Cd2+ ion, corresponding to the TIC/TID mechanism.Öğe Investigation of the lipophilicity of 2-benzoylpyridine-thiosemicarbazone based on the ion transfer across the liquid/liquid interface(PEKING UNIV PRESS, 2008) Akgemci, Emine Güler; Bingöl, Haluk; Özçelik, Mehmet; Ersöz, MustafaThe ion transfer reaction of 2-benzoylpyridine-thiosemicarbazone (HL), which has antimicrobial and antifungal properties and anticancer activity, has been studied to determine its lipophilicity by cyclic voltammetry at the water/1,2-dichloroethane (1,2-DCE) interface. The physicochemical parameters such as standard partition coefficient (IgP(I)) and the standard Gibbs energy of transfer of the protonated form of the ligand were measured as a function of pH in aqueous phase. The protonated form of the ligand exhibited reversible or quasi-reversible voltammograms at the 1,2-DCE in the range of pH 1-5. ne protonation constants of the ligand, pK(a1) and pK(a2), were determined spectrophotometrically and were found to be 12.14 and 3.24, respectively. The standard Gibbs energy of transfer and the partition coefficient of neutral species (lgP(N)) were also determined by the shake-flask method. The standard Gibbs energy of transfer of this compound across the water/1,2-DCE interface was evaluated as the quantitative measure of its lipophilicity. The difference between IgP(I) and lgP(N) was related to the degree of charge delocalization and was used to evaluate qualitatively the lipophilicity of the ligand.Öğe Kinetic study of copper(II) complexation with 9-ethyl-3-carbazolecarboxaldehyde-thiosemicarbazone and kinetic-spectrophotometric determination of copper(II)(MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006) Bingöl, Haluk; Akgemci, Emine Güler; Atalay, T.The kinetics of complexation reaction of Cu(II) with 9-ethyl-3-carbazolecarboxaldehyde-thiosemicarbazone (ECCAT) has been examined spectrophotometrically. The ligand was synthesized for the first time. The complexation reaction was carried out in a DMF-water medium at 35 degrees C. The complex has maximum absorbance at 393 nm. Kinetic and activation parameters of the complexation reaction were calculated by the Arrhenius and Eyring equations using the data obtained from investigating the effect of temperature on reaction rates under the specified conditions. We also proposed reaction rate equations. Based on the studied complexation reaction, a simple kinetic method for the spectrophotometric determination of copper(II) has been developed. The calibration graphs are linear in the concentration range 0.2-1.9 mu g/mL. The species that caused interference were investigated.Öğe Kiral Sensör Olarak Ferrosen Türevli YeniSchiff Bazının Sentezi(2015) Uçar, Asuman; Fındık, Mükerrem; Bingöl, Haluk; Güler, Ersin; Özcan, EmineFerrosen ve ferrosenil bileşikleri enerji ve elektron transferi gerçekleştirebilmesinden dolayı floresans çalışmalarında yaygın olarak kullanılmıştır (1). Yüksek seçiciliğin yanında analitik, biyolojik, klinik ve biyokimya alanlarında potansiyel uygulamaları nedeniyle enantiyoseçici floresans sensör çalışmaları literatürlerde yer almaktadır (2). Aminoasitler hem doğal kiral moleküller olduğu için hem de amid bağları mükemmel hidrojen bağı yaptıkları için kiral reseptor eldesinde önem taşımaktadırlar (3). Bu çalışmada kiral yapıda olan 3 bileşiği sentezlenmiş ve floresans özellikleri çalışılmıştır. Bu bileşiğin çeşitli kiral aminoasitlerle (D- Metiyonine, L- Metiyonine, DAlanin, L-Alanin, D-Valin, L-Valin, L-Serin, D-Serin, D-Histidin, L-Histidin, D-Sistein, LSistein D- Treonin, L- Treonin) etkileşimi sonucu floresans değişimleri incelendiğinde D-metiyonine karşı gözle görülür bir değişim söz konusuyken incelenen diğer amino asitlere karşı bu artışın mevcut olmadığı görülmüştür. Bu sonuçlar sentezlenen bileşiğin D-metiyonin enantioselektif tanıması için kullanışlı bir sensor olduğunu göstermektedir.Öğe New copper(II) and nickel(II) complexes of 4-morpholinoaceto-phenone thiosemicarbazone: Structural, electrochemical and antimicrobial studies(WILEY-V C H VERLAG GMBH, 2007) Bingöl, Haluk; Coşkun, Ahmet; Akgemci, Emine Güler; Kaya, Baştürk; Atalay, Tevfik4-Morpholinoacetophenone thiosemicarbazone, MAPT, and its nickel(II) and copper(II) complexes have been prepared and characterized by elemental analysis, magnetic susceptibility, spectral methods (FT-IR, H-1 NMR) and cyclic voltammetry. Electrochemical behaviors of the complexes have been studied by cyclic voltammetry in DMF media showing metal centered reduction processes for both of them. The redox properties, nature of the electrode processes and the stability of the complexes were discussed. [Cu(MAPT)(2)]Cl-2 complex shows Cu(II)/Cu(I) couple and quasi-reversible wave associated with the Cu(III)/Cu(II) process. The reduction/oxidation potential values depend on the structures of complexes. Also, the antimicrobial activities of these complexes were determined against S. aureus, E. coli and B. subtilis.
