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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 Application of L-Proline Derivatives as Chiral Shift Reagents for Enantiomeric Recognition of Carboxylic Acids(WILEY, 2011) Naziroglu, Hayriye Nevin; Durmaz, Mustafa; Bozkurt, Selahattin; Sirit, AbdulkadirFour proline-derived chiral receptors 5-8 were readily synthesized starting from L-proline. The enantiomeric recognition ability of chiral receptors was examined with a series of carboxylic acids by H-1 NMR spectroscopy. The molar ratio and the association constants of the chiral compounds with each of the enantiomers of guest molecules were determined by using Job plots and a nonlinear least-squares fitting method, respectively. The Job plots indicate that the hosts form 1:1 instantaneous complexes with all guests. The receptors exhibited different chiral recognition abilities toward the enantiomers of racemic guests. Among the chiral receptors used in this study, prolinamide 6 was found to be the best chiral shift reagent and is effective for the determination of the enantiomeric excess of chiral carboxylic acids. Chirality 23:463-471, 2011. (C) 2011 Wiley-Liss, Inc.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 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]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 Kinetic study on removal of toxic metal Cr(VI) through a bulk liquid membrane containing p-tert-butylcalix[4]arene derivative(ELSEVIER, 2011) Alpaydın, Sabri; Saf, Ahmet O.; Bozkurt, Selahattin; Sirit, AbdulkadirThe transport of Cr(VI) from aqueous solutions through bulk liquid membrane was studied using p-tert-butylcalixpliarene 3-diethylaminopropyl diamide derivative as a carrier. The aqueous solution of potassium dichromate was used as the model contaminant. The kinetic parameters (k(1), k(2), t(max), R-m(max), J(d)(max) and J(a)(max)) for the forward and the back extraction were calculated by means of Cr(VI) concentrations of the donor and the acceptor phase. The results showed that it was possible to transport 96.65% of Cr(VI) from the acidic donor solutions to the acceptor solutions at the optimum operating conditions after 10 h contact time. The highest transport efficiency was observed at pH 2 in the donor phase and at pH 5 in the acceptor phase. It was shown that the transport of Cr(VI) stem from pH difference between the donor and the acceptor phases. The activation energy values were calculated as 5.77 and 7.99 kJmol(-1) for the forward and the back extraction, respectively. It was indicated that the process was diffusionally controlled by dichromate anions. The experimental results demonstrated that p-tert-butylcalix[4]arene derivative was an effective carrier for the transport of Cr(VI). (C) 2011 Elsevier B.V. All rights reserved.Öğe Synthesis and dichromate anion sorption of silica gel-immobilized calix[4]arenes(ELSEVIER SCIENCE BV, 2009) Bozkurt, Selahattin; Kocabas, Erdal; Durmaz, Mustafa; Yilmaz, Mustafa; Sirit, AbdulkadirThree new silica gel-immobilized calix[4]arene polymers 9-11 have been prepared via modification of calix[4]arene mono amido derivatives 3-5 with 3-aminopropyl triethoxysilane (APTES) and activated silica gel, respectively. The polymers were characterized by Fourier transform infrared spectroscopy, elemental analysis and thermal gravimetric analysis. The solid-liquid extraction properties of ligands 3-5 along with their immobilized derivatives 9-11 towards dichromate (HCr2O7-/Cr2O72-) anions were reported. It was found that these calix[4]arene-based polymers have high extraction abilities towards dichromate anions as compared to their monomeric precursors. (C) 2008 Elsevier B.V. All rights reserved.Öğe Synthesis of 1,3-(distal) diamide substituted calix[4]arene based receptors for extraction of chromium (VI)(TAYLOR & FRANCIS LTD, 2007) Durmaz, Mustafa; Bozkurt, Selahattin; Sirit, Abdulkadir; Yilmaz, MustafaThe synthesis of novel diamide derivatives of calix[4]arene by aminolysis of calix[4]arene diesters was reported. The H-1 and C-13 NMR, data showed that the synthesized compounds exist in the cone conformation. The complexation properties of these calix[4]arenes have been studied towards Cr2O7=/HCr2O7- anions and it has been found that the protonated alkyl ammonium forms of calix[4]arene diamide derivatives (5,11,17,23-tetra-tert-butyl-25,27-(diethylpiperidineacetamido)26,28- dihydroxy-calix[4]arene 3 and 25,27-(diethyl-piperidineacetamido)26,28-dihydroxycalix[4]arene 4) are effective extractants for transferring HCr2O7-/Cr2O7= anions.Öğe Synthesis of calix[4]arene mono and diamide derivatives and selective complexation of alkali and alkaline earth cations(TAYLOR & FRANCIS INC, 2007) Bozkurt, Selahattin; Durmaz, Mustafa; Sirit, Abdulkadir; Yilmaz, MustafaThe synthesis of mono and diamide derivatives of the p-tert-butylcalix[4]arenes/calix[4]arenes from the reaction of 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarbonyl-methoxy-26,28-dihydroxycalix[4]arene 1 and 25,27-diethoxycarbonyl-methoxy-26,28-dihydroxycalix[4] arene 2 with various primary amines were reported. The effect of reaction time and steric hindrance of the primary amines used on the reactions have been investigated. All the amide derivatives of calix[ 4] arene are in a cone conformation according to the H-1-NMR doublet-doublet pattern of the protons of the methylene groups between the aromatic rings. The complexing properties of these compounds toward selected alkali and alkaline earth metal cations are also studied. It has been observed that receptor 8 is a selective extractant for Cs+ and Sr2+ cations.Öğe Synthesis of new chiral calix[4]azacrowns for enantiomeric recognition of carboxylic acids(PERGAMON-ELSEVIER SCIENCE LTD, 2008) Demirtas, Havva Nur; Bozkurt, Selahattin; Durmaz, Mustafa; Yilmaz, Mustafa; Sirit, AbdulkadirTwo novel chiral calix[4]azacrown ethers 4 and 5 bearing a furfuryl group on the nitrogen atom were developed by the reaction of dibromo- or ditosyl derivatives of p-tert-butylcalix[4]arenes 2 and 3 with a chiral diol, 1. The enantioselective recognition of these receptors towards the enantiomers of racemic carboxylic acids has been studied by H-1 NMR spectroscopy. The molar ratio and the association constants of the chiral compounds 4 and 5 with each of the enantiomers of guest molecules were determined by using job plots and a nonlinear least-squares fitting method, respectively. The job plots indicate that both of the hosts form 1:1 instantaneous complexes with (R)- OF (S)-mandelic acid and (L)- or (D)-dibenzoyl-tartaric acid. The receptors exhibited different chiral recognition abilities towards the enantiomers of racemic guests. (C) 2008 Elsevier Ltd. All rights reserved.Öğe Yeni kiral ß-hidroksi amin ve kaliks[4]aren türevlerinin sentezi, enantiyomerlerin tanınmasında kullanılması(Selçuk Üniversitesi Fen Bilimleri Enstitüsü, 2011-10-20) Bozkurt, Selahattin; Sırıt, Abdulkadir; Yılmaz, MustafaBu çalışmada, çeşitli kiral ve akiral amin türevleri ile (R)-(?)-N-(2,3- epoksipropil)ftalimid (3) bileşiğinin reaksiyonu sonucunda % 56?93 verimle yedi farklı optikçe aktif amino alkol türevi sentezlendi. Bu optikçe aktif amino alkol türevlerinin (8?11) rasemik yapıdaki karboksilik asitlere karşı enantiyomerik tanıma özellikleri 1H NMR spektroskopisi kullanılarak araştırıldı. Bu çalışmada kullanılan kiral reseptörler arasında, en iyi kiral kaydırma reaktifinin amino alkol türevi 9 olduğu belirlendi. Ayrıca, kiral ftalimid türevleri hidrazin mono hidrat ile indirgenerek kiral primer amin bileşikleri (12?15 ve 22?24) hazırlandı. Bu primer amin türevleri ile 25,27-dietoksikarbonilmetoksi-26,28-dihidroksi-5,11,17,23-(tetra-ter)bütil-kaliks[4]aren (2) bileşiğinin reaksiyonu sonucunda yedi farklı yeni kiral amit kaliks[4]aren bileşiği (25?31) başarıyla sentezlendi. Bazı amino asit metil ester tuzları ve mandelik asitin taşınması kiral kaliks[4]arenler (25?30) kullanılarak sıvı-sıvı membran sistemi ile çalışıldı. Özellikle kaliks[4]aren türevi 25 'in triptofan metilesterin taşınmasında, D enantiyomerini L enantiyomerine göre 3.29 kat daha fazla taşıma gösterdiği tespit edildi. Elde edilen sonuçlara göre enantiyoseçiciliğin ilk iki saat içinde artmasına rağmen bundan sonraki zamanda azaldığı gözlendi.
