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Öğe Adsorption of phenols from contaminated water through titania-silica mixed imidazolium based ionic liquid: Equilibrium, kinetic and thermodynamic modeling studies(TAYLOR & FRANCIS INC, 2016) Ismail, Nor Atiqah; Bakhshaei, Shabnam; Kamboh, Muhammad Afzal; Manan, Ninie Suhana Abdul; Mohamad, Sharifah; Yilmaz, MustafaThe present study describes the synthesis and characterization of titania-silica mixed imidazolium based ionic liquid (Ti-Si-IL) as well as evaluation of its adsorption behavior towards the 2,4-dinitrophenol (2,4-DNP) and 2,4,6-trichlorophenol (2,4,6-TCP). Synthesized Ti-Si-IL adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), BET surface area Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA) and elemental analysis (CHN). The adsorption of 2,4-DNP and 2,4,6-TCP on Ti-Si-IL was investigated systematically by evaluating the effects of adsorbent dosage, initial pH, contact time and temperature. Satisfactory adsorption 95% and 65% for 2,4-DNP and 2,4,6-TCP was observed at pH 4 and 6, respectively. The kinetic results for 2,4-DNP and 2,4,6-TCP on Ti-Si-IL indicated that the kinetic data follows pseudo-second-order model (R-2 = 0.9985 and 0.9750, respectively). Adsorption isotherms were fitted well by the Langmuir model for 2,4-DNP (q(m) = 44.64mg g(-1) at 318K) and Freundlich model for 2,4,6-TCP (K-F = 0.63mg g(-1) at 318K). The +H degrees and -G degrees values demonstrated that the adsorption of 2,4-DNP was endothermic and spontaneous in nature. While the -H degrees and +G degrees values for 2,4,6-TCP adsorption demonstrated exothermic and comparatively nonspontaneous. During the removal process, the role of different functional groups, cyclic structure was monitored and found that the ionic property as well as - interactions of host molecules played important role in the extent of adsorption.Öğe Amino alcohol based chiral solvating agents: synthesis and applications in the NMR enantiodiscrimination of carboxylic acids(PERGAMON-ELSEVIER SCIENCE LTD, 2011) Bozkurt, Selahattin; Durmaz, Mustafa; Naziroglu, Hayriye Nevin; Yilmaz, Mustafa; Sirit, AbdulkadirFour optically active amino alcohols were synthesized via the ring opening of (R)-N-(2,3-epoxypropyl)phthalimide with (R)-2-phenyl glycinol, (1R,2S)-cis-1-amino-2-indanol, (R)-2-amino-1-butanol and (S)-phenyl ethylamine in 73-93% yields. The enantioselective recognition of these receptors towards the enantiomers of racemic carboxylic acids was studied by (1)H NMR spectroscopy. The molar ratio and the association constants of the chiral compounds with each of the enantiomers of the guests were determined by using Job plots and a non-linear least-squares fitting method, respectively. Large non-equivalent chemical shifts (up to 30.0 Hz) can be achieved in the presence of chiral amino alcohols 2 and 5. Amongst the chiral receptors used, compound 5 was found to be the best chiral shift reagent, and was effective in the determination of the enantiomeric excess of chiral carboxylic acids. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Anion Extraction Properties of a New "Proton-Switchable" Terpyridin-Conjugated Calix[4]arene(AMER CHEMICAL SOC, 2014) Sayin, Serkan; Eymur, Serkan; Yilmaz, MustafaA new terpyridin-conjugated calix[4]arene derivative has been synthesized via selectively substitution of p-tert-butylcalix[4]arene. The synthesized ligand was characterized by FTIR, H-1 NMR, C-13 NMR, C-13-DEPT-135 and elemental analysis. Moreover, the dichromate extraction capability of the compound regarding the removal of toxic oxyanion from aqueous solutions was discussed in a liquid-liquid extraction system. The results indicated that the pH of the solution is a key parameter for the efficient extraction of Cr(VI) and that compound 6 is partially protonated in acidic conditions. Hence, facilitating binding of dichromate results from both electrostatic interactions and hydrogen bonding. To understand the selectivity of 6, the retention of dichromate anions in the presence of NO3-, Cl-, and SO42- anions at pH 1.5 was also discussed.Öğe Bronsted acidic magnetic nano-Fe3O4-adorned calix[n]arene sulfonic acids: synthesis and application in the nucleophilic substitution of alcohols(PERGAMON-ELSEVIER SCIENCE LTD, 2014) Sayin, Serkan; Yilmaz, MustafaThree magnetically recoverable Bronsted acidic calix[n]arene derivatives were successfully constructed by immobilizing calix[n]arene sulfonic acids onto silica-coated magnetic nanoparticles, a process, which allows calix[n]arene derivatives to acquire magnetic properties. All of the magnetically recoverable Bronsted acidic calix[n]arenes efficiently catalyze the coupling of electron-rich arenes with some alcohols in water. After separation and recovery from the reaction mixture by a simple magnet, these Bronsted acidic calix[n]arenes can be recycled many times without losing their catalytic activity. (C) 2014 Elsevier Ltd. All rights reserved.Öğe A calix[4] arene oligomer and two beta-cyclodextrin polymers: Synthesis and sorption studies of azo dyes(TAYLOR & FRANCIS INC, 2007) Ozmen, Elif Yilmaz; Sirit, Abdulkadir; Yilmaz, MustafaTwo insoluble beta-cyclodextrin polymers were synthesized by reacting beta-cyclodextrin with hexamethylene diisocyanate ( HMDI) or 4,4'methylene bis phenyldiisocyanate (MPDI) as a crosslinking agent and a calix[4]arene-based oligomer was prepared by the condensation of p-tert-butylcalix[4] arene with HMDI and utilized to remove selected water-soluble azo dyes from aqueous solution. Oligomer 2 was found to be a poor sorbent for the azo dyes. The influence of several parameters ( pH, contact time, and NaCl concentration) on the sorption capacity was evaluated using the batch and recycling column methods. The proposed sorption mechanism involved several kinds of interactions: physical adsorption, hydrogen bonding and formation of an inclusion complex due to the beta-CD molecules through host-guest interactions.Öğe Calix[4]arene derivative bearing imidazole groups as carrier for the transport of palladium by using bulk liquid membrane(ELSEVIER SCIENCE BV, 2012) Akin, Ilker; Erdemir, Serkan; Yilmaz, Mustafa; Ersoz, MustafaThe carrier activity of calix[4]arene containing imidazole groups towards the facilitated transport of palladium(II) through dichloromethane bulk liquid membrane has been studied. The optimum transport conditions were established by the studies on the effect of pH, feed concentration, carrier concentration, receiver phase concentration and transport time. A solution of 1 M hydrochloric acid (HCl) served as receiving phase for maximum transport of the metal ion. Maximum transport efficiency was observed for Pd(II) ion when it was present in the concentration of 10(-3) M and the transport efficiency after 24 h was found as 95%. (C) 2012 Elsevier B.V. All rights reserved.Öğe A calix[4]arene derivative-doped perchlorate-selective membrane electrodes with/without multi-walled carbon nanotubes(SPRINGER HEIDELBERG, 2017) Erturun, H. Elif Kormali; Ozel, Ayca Demirel; Ayanoglu, Melek Nur; Sahin, Ozlem; Yilmaz, MustafaIn this study, poly (vinyl chloride)(PVC) membrane electrodes with/without multi-walled carbon nanotubes (MWCNTs) based on a calix[4]arene derivative for perchlorate ion were described. The influence of membrane composition, pH, conditioning solution on the potentiometric response of the electrodes was investigated. Perchlorate-selective PVC membrane electrode exhibited a slope of 47.8 +/- 0.6 mV/pClO(4) in the range of 1.0 x 10(-7)-1.0 x 10(-1) mol L-1 at pH 4.0 while the coated Pt electrodes with MWCNT-OH, MWCNT-COOH and MWCNT displayed slopes of 46.1 +/- 0.7 mV/pClO(4) (5.0 x 10(-6)-1.0 x 10(-1) mol L-1), 50.4 +/- 1.9 mV/pClO(4) (1.0 x 10(-6)-1.0 x 10(-1) mol L-1) and 44.4 +/- 0.3 mV/pClO(4) (1.0 x 10(-5)-1.0 x 10(-1) mol L-1), respectively. Other response characteristics of these electrodes such as response time, lifetime and detection limit were identified, and the selectivity coefficients towards various anions were calculated by separate solution method. Moreover, the perchlorate-selective electrodes described here were successfully used as an indicator electrode for the determination of perchlorate in real samples such as tap water, river water and human urine by direct calibration method.Öğe Calix[4]arene derivatives as dopamine hosts in electrochemical sensors(ELSEVIER SCIENCE SA, 2015) Kurzatkowska, Katarzyna; Sayin, Serkan; Yilmaz, Mustafa; Radecka, Hanna; Radecki, JerzyIn this work, we introduce the use of an electrochemical sensor based on ion-channel mechanism in order to investigate the interaction between different-functionalized calixarene mercaptoalkyl derivatives and dopamine at the aqueous/organic interface. Three different calix[4]arene derivatives, functionalized with mercaptoalky groups at the upper-rim of calix[4]arene, were synthesized, and their structures were characterized by FTIR, H-1 and C-13 NMR spectroscopy, and elemental analysis techniques. Moreover, these calixarene-mercaptoalkyl derivatives were grafted onto gold electrode surface by covalent Au-S bound. To elucidate the functional groups' influences on the signal generation mechanism, three different-substituted calixarene-mercaptoalkyl derivatives, with an opposite arrangement of the functional moieties and mercaptoalkyl groups at the lower and the upper rim of the calixarene, were interacted for the first time with dopamine. The formation of a supramolecular complex between the calix[4]arene host and the dopamine guest were confirmed by Osteryoung square-wave voltammetry with [Ru(NH3)6]Cl-3 as an redox active marker. The proposed electrochemical sensors were suitable for the determination of dopamine in the concentration range from 1.0 x 10(-11) M to 1.0 x 10(-6) M. In order to demonstrate the applicability of the sensors proposed, the electrochemical determination of dopamine in the presence of ascorbic acid and uric acid were checked. It was proved that these interferences did not influence on dopamine determination. The detection limit was estimated as 4.9 pM. (C) 2015 Elsevier B.V. All rights reserved.Öğe A Calix[4]arene-tren modified electrode for determination of Lead ions in aqueous solution(ACG PUBLICATIONS, 2019) Kocer, Mustafa Baris; Erdogan, Zehra Ozden; Oguz, Mehmet; Kucukkolbasi, Semahat; Yilmaz, MustafaIn this study, a simple and sensitive electrochemical sensor based on Calix[4]arene-tren (Calix-tren) modified glassy carbon (GC) electrode was developed for the determination of Pb (II) ions. Electrochemical behavior of Calix-tren modified electrodes were investigated by using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicate that Calix-tren modified GC electrode provides good electron transmission pathway than bare GC electrode. The amount of Pb (II) was determined by differential pulse anodic stripping voltammetric analysis as a sensitive detection technique. The experimental parameters such as pH, deposition time and deposition potential were optimized. The optimum pH value was selected as 7.0. The effect of deposition potential and deposition time on the peak current was tested and the optimum values were chosen as -1.2 V and 120 s, respectively. Under the optimal conditions, the working range of the developed sensor was determined as 0.48-2.31 mu M, limit of detection (LOD) was 0.11 mu M and the RSD obtained in the reproducibility study was 2.78 %. It was also found that the developed method could be used in the determination of Pb (II) ions in real samples with satisfactory results.Öğe CALIXARENE BASED SORBENTS FOR THE EXTRACTION OF IONS AND NEUTRAL MOLECULES(NOVA SCIENCE PUBLISHERS, INC, 2009) Yilmaz, Mustafa; Memon, ShahabuddinSorption of ions as well as organic molecules from aqueous media by calixarene based materials has been a widely developing area in material science and technology since last few decades. Mostly, it is achieved by the immobilization (physically or chemically) of modified calixarenes onto various supports such as polymers, silica, and resins. The calixarene macrocycles due to their bowl-shaped geometry are indeed used as hosts allowing organic and inorganic guests to coordinate/sorb onto their cavity. The possibility of designing versatile organic, coordination and organometallic architectures at the lower (narrow) and upper (wide) rims of the calixarenes are also very appealing for extending the cavity, or to take advantage of the proximity to promote substituent interactions. Thus, novel calixarene derivatives are continue to being synthesized and appended in polymeric materials in order to obtain regenerable resins for the recovery of various elements (metals/metalloids/non-metals) and neutral molecules. The calixarene based sorbents are generally applied in various fields such as catalyst recovery, power plant, agriculture, metals finishing, microelectronics, biotechnology processes, rare earths speciation, and potable water. Besides this, they find applications in the area of selective ion extractions, receptors, catalysis, optical devices, chemical sensor devices, the stationary phase for capillary chromatography, ion transport membranes, biomimetics, and luminescence probes etc. This survey is focused to have an overview of calixarene based sorbents for the extraction of ions and neutral molecules. The article does not, however, attempt to cover all of the different approaches to extraction processes.Öğe Calixarene-based chiral phase-transfer catalysts derived from cinchona alkaloids for enantioselective synthesis of alpha-amino acids(PERGAMON-ELSEVIER SCIENCE LTD, 2008) Bozkurt, Selahattin; Durmaz, Mustafa; Yilmaz, Mustafa; Sirit, AbdulkadirThe synthesis of the first calixarene-based chiral phase-transfer catalysts derived from cinchona alkaloids has been achieved in two steps from p-tert-butylcalix[4]arene. The catalytic efficiency of the chiral calix[4]arenes 3a-c was evaluated by carrying out the phase-transfer alkylation of N-(diphenylmethylene)glycine ethyl ester with benzyl bromide. Various factors that affect the chemical yield and enantio selectivity were also examined. Benzylation of glycine imine 4 using calix[4]arene- based dimeric catalyst 3a as a chiral phase-transfer catalyst in toluene/CHCl3 mixture (7:3 v/v) at 0 degrees C gave the best enantioselectivities and yields in the presence of aqueous NaOH. (C) 2008 Elsevier Ltd. All rights reserved.Öğe Calixarene-based receptors for molecular recognition(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, 2013) Yilmaz, Mustafa; Erdemir, SerkanCalixarene-based molecular receptors have been a widely developing area in material science and technology for the last few decades. Due to their bowl-shaped geometry, calixarene macrocycles are used as hosts allowing organic and inorganic guests to coordinate/sorb onto their cavity. This work briefly reviews the recent development of calixarenes.Öğe Calixarene-proline functionalized iron oxide magnetite nanoparticles (Calix-Pro-MN): An efficient recyclable organocatalyst for asymmetric aldol reaction in water(ELSEVIER SCIENCE BV, 2015) Akceylan, Ezgi; Uyanik, Arzu; Eymur, Serkan; Sahin, Ozlem; Yilmaz, MustafaCalix[4]arene-based chiral organocatalyst derived from L-proline supported onto well-defined (15 +/- 3 nm) magnetic Fe3O4 nanoparticles was used as a highly active, recoverable, and reusable catalyst for the asymmetric aldol reaction in water without need for organic solvents. The chiral organocatalyst showed high catalytic activity (up to 94%), enantioselectivity (up to 93%) and diastereoselectivity (up to 97:3) for the reaction between cyclohexanone and aromatic aldehydes. The catalyst could easily separated using an external magnetic field and reused for several times without any significant loss of activity. (C) 2015 Elsevier B.V. All rights reserved.Öğe Calixarenes in Lipase Biocatalysis and Cancer Therapy(BENTHAM SCIENCE PUBL LTD, 2016) Karakurt, Serdar; Kellici, Tahsin F.; Mavromoustakos, Thomas; Tzakos, Andreas G.; Yilmaz, MustafaCalixarenes are supramolecular structures characterized by their "calix" shape and their easy synthetic accessibility. They are amphiphilic in nature, thus they can bear in their structure both hydrophobic and hydrophilic features as well as charged groups. They are characterized by architectural plasticity responsible for their unique fine-tuned properties that can be shaped for an array of applications. Herein, we will focus, on their diverse available applications, and give special emphasis on biocatalysis and cancer therapy as two modern directions and emerging fields of interest that have been sporadically explored in the literature and can pave the way for the discovery of novel therapeutics. This review provides the first exhaustive examination on the enhanced catalytic activity and selectivity of calixarene-based encapsulated biocatalysts towards the synthesis of bioactive molecules. The application of functionalized calixarenes in cancer therapy is also analyzed towards the spatiotemporal control they can offer in targeted drug delivery.Öğe Catalytic effect of calix[n]arene based sol-gel encapsulated or covalent immobilized lipases on enantioselective hydrolysis of (R/S)-naproxen methyl ester(SPRINGER, 2012) Erdemir, Serkan; Yilmaz, MustafaIn this paper the catalytic performance of the immobilized lipases was investigated in the presence of calixarene based polymers using different immobilization techniques. For this reason, Candida rugosa lipase was encapsulated in sol-gel matrices using alkoxysilane precursors and calix[n]arene based silica polymers as additives. The hydrolytic activities of encapsulated lipases were evaluated and compared with the free lipase and covalently immobilized lipases (CnP-L). These encapsulated lipases were also used in the kinetic resolution of the R/S-Naproxen methyl ester. The results indicated that the C6P encapsulated lipase has significantly higher conversion and enantioselectivity as compared to the free lipase; other encapsulated lipases and CnP-L. The optimal pH and temperature region of the C6P encapsulated lipase in the kinetic resolution of the R/S-naproxen methyl ester were 7.0 and 55 A degrees C. Nevertheless, the encapsulated lipases have good stability, adaptability and reusability in comparison with the free enzyme.Öğe Chiral calix[4]arenes bearing amino alcohol functionality as membrane carriers for transport of chiral amino acid methylesters and mandelic acid(WILEY-BLACKWELL, 2012) Bozkurt, Selahattin; Yilmaz, Mustafa; Sirit, AbdulkadirNovel chiral calix[4]arene derivatives bearing amino alcohol moieties at the lower rim have been synthesized from the reaction of p-tert-butylcalix[4]arene diester with various amino alcohols. The transport of amino acid esters (phenylglycine, phenylalanine, and tryptophan methyl esters hydrochloride) and mandelic acid were studied through chloroform bulk liquid membrane system using chiral calix[4]arenes 15-20. All these receptors have been found to act as carriers for transport of aromatic amino acid methylesters and mandelic acid from the aqueous source phase to the aqueous receiving phase. The influence of calixarene and guest structures upon transport through liquid membrane is discussed. Chirality 24: 129-136, 2012. (c) 2011 Wiley Periodicals, Inc.Öğe Chiral calix[4]arenes bearing aminonaphthol moieties as membrane carriers for amino acid methyl esters and mandelic acid(PERGAMON-ELSEVIER SCIENCE LTD, 2011) Durmaz, Mustafa; Bozkurt, Selahattin; Naziroglu, Hayriye Nevin; Yilmaz, Mustafa; Sirit, AbdulkadirChiral calix[4]arene derivatives functionalized at the lower rim with chiral aminonaphthol units have been prepared. The structures of these receptors were characterized by a combination of (1)H NMR, (13)C NMR, FTIR and elemental analysis. The transport of amino acid derivatives (phenylglycine, phenylalanine and tryptophan methyl ester hydrochlorides) and mandelic acid were studied through a bulk liquid membrane in the presence of chiral calix[4]arene derivatives. The transport rate and enantioselectivity of the amino acid esters studied depended mainly upon the structure of the chiral receptors. The influence of calixarene and amino acid ester structures upon transport through a liquid membrane is discussed. The receptors with hydrogen bonding sites and aromatic groups showed considerable higher transport rates and stereoselectivities. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Chiral Calix[4]arenes-Bearing Prolinamide Functionality as Organocatalyst for Asymmetric Direct Aldol Reactions in Water(TAYLOR & FRANCIS LTD, 2018) Sahin, Ozlem; Eymur, Serkan; Uyanik, Arzu; Akceylan, Ezgi; Yilmaz, MustafaThe chiral calix[4]arene derivative (6) bearing an L-prolinamido group has been designed and proved to be a water compatible efficient organocatalysts for a direct enantioselective aldol reaction. Compound 6 catalyzes the aldol reaction of cyclohexanone and a variety of aromatic aldehydes yielding anti-aldol products in high yield with enantioselectivities of up to 93% and diastereoselectivity of up to 95:5.Öğe Chiral calix[4]azacrowns for enantiomeric recognition of amino acid derivatives(PERGAMON-ELSEVIER SCIENCE LTD, 2009) Demirtas, Havva Nur; Bozkurt, Selahattin; Durmaz, Mustafa; Yilmaz, Mustafa; Sirit, Abdulkadirin this study the synthesis of novel chiral calix[4]azacrown derivatives has been reported. The enantioselectivity of Chiral receptors was investigated by using UV-vis spectroscopy. All the chiral calix[4]arene derivative,; exhibited certain chiral recognition toward the enantiomers of phenylalanine (Phe-OMe.HCl) and alanine methyl ester hydrochlorides (Ala-OME.HCl). As a chiral receptor, the furfuryl-armed calix[4]azacrown ether 7 has the best enantiomeric discriminating ability for alpha-amino acid ester hydrochlorides (up to K-L/K-D 2.08, Delta Delta G(0) 1.82 KJ mol (1)) in CHCl3. The enantiomeric recognition abilities for 1,guests are also discussed from a thermodynamic point of view. (C) 2009 Elsevier Ltd. All rights reserved.Öğe Chiral Calixarenes -- 2(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, 2009) Sirit, Abdulkadir; Yilmaz, Mustafa[Abstract not Available]
