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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 Detection of Hg2+ ion in aqueous media by new fluorometric and colorimetric sensor based on triazole-rhodamine(ELSEVIER SCIENCE SA, 2015) Erdemir, Serkan; Kocyigit, Ozcan; Malkondu, SaitA highly efficient and selective rhodamine B sensor bearing triazole unit (RHT) as the metal ion receptor was designed and synthesized. RHT was characterized by H-1 NMR, C-13 NMR, APT COSY, FTIR, elemental analysis, and also its binding selectivity toward various metal ions was studied. Fluorescence enhancement by factors 24 times was achieved upon selective interaction with Hg2+ ion over other metal ions in aqueous solutions. Selective fluorescent enhancement of RHT was attributed to ring opening from the spirolactam (nonfluorescent) to ring-opened amide (fluorescent). Also, distinct color changes from colorless to pink provided "naked eye" detection of Hg2+. (C) 2015 Elsevier B.V. All rights reserved.Öğe Fluorescent labelling of DNA on superparamagnetic nanoparticles by a perylene bisimide derivative for cell imaging(ELSEVIER SCIENCE BV, 2015) Maltas, Esra; Malkondu, Sait; Uyar, Pembegul; Ozmen, MustafaN,N'-Bis[tris-(2-aminoethyl) amine]-3,4,9,10-perylenetetracarboxylic diimide (PBI-TRIS), nonfluorescent dye was used to fluorescent labelling of DNA. For this aim, (3-aminopropyl) triethoxysilane (APTS) modified superparamagnetic iron oxide nanopartides (SPIONs) were synthesized to provide a suitable surface for binding of DNA. Amine functionalized nanoparticles showed a high immobilization capacity (82.70%) at 25 mg of nanoparticle concentration for Calf thymus DNA. Binding capacity of PBI-TRIS to DNA-SPION was also found as 1.93 mu M on 25 mg of nanoparticles by using UV-vis spectroscopy. Binding of PBI-TRIS to DNA onto nanoparticles was also characterized by scanning electron microscopy and infrared spectroscopy. The confocal images of PBI-TRIS labelled DNA-SPION and breast cells were taken at 488 and 561.7 nm of excitation wavelengths. Cell image was also compared with a commercial dye, DAPI at 403.7 nm of excitation wavelength. Results showed that PBI-TRIS can be used for cell staining. (C) 2014 Elsevier B.V. All rights reserved.Öğe Fluorogenic Recognition of Zn2+, Al3+ and F- Ions by a New Multi-Analyte Chemosensor Based Bisphenol A-Quinoline(SPRINGER/PLENUM PUBLISHERS, 2015) Erdemir, Serkan; Kocyigit, Ozcan; Malkondu, SaitA new available multi-analyte fluorescent sensor based on a bisphenol A-quinoline conjugate (BFQ) was synthesized in two facile steps and was characterized systematically. BFQ exhibited an effectively selective and sensitive recognition toward Zn(2+)and Al3+ cations in EtOH-H2O (v/v = 9/1) over other cations and F- anion in CH3CN over other anions with remarkably enhanced fluorescent intensities. According to the quantum yield (I broken vertical bar) measurements, BFQ-Zn2+, BFQ-Al3+ and BFQ-F- complexes showed 16, 22 and 30 times higher I broken vertical bar values than BFQ, respectively. The complexation properties of BFQ with Zn2+, Al3+ and F- ions were also examined by H-1 NMR titration experiments.Öğe A highly selective and sensitive benzothiazole-based 'turn-on' fluorescent sensor for Hg2+ ion(WILEY, 2015) Erdemir, Serkan; Malkondu, Sait; Alici, OnderA simple benzothiazole-based fluorescent probe (TDA) for the determination of Hg2+ ion in aqueous solutions was synthesised in one step and characterised by H-1 NMR, C-13 NMR, APT, COSY, FTIR, and elemental analysis. TDA shows a significant fluorescence change upon the interaction of Hg2+ ion in DMF-water (v/v=1/1), while only minor changes in fluorescence intensity are observed with 18 other metal ions. Fluorescence enhancement by a factor of 15 is achieved upon selective interaction with Hg2+ ion. The Hg2+ ion detection process is found to be pH dependent; therefore, TDA could be feasible within a pH range of 4.0-7.0.Öğe A highly selective and sensitive perylenebisimide-based fluorescent PET sensor for Al3+ determination in MeCN(PERGAMON-ELSEVIER SCIENCE LTD, 2014) Malkondu, SaitA novel 'turn-on' fluorescent probe with perylene tetracarboxylic bisimide (PBI) as the fluorophore and di(2-(salicylideneamino))ethylamine (DSEA) as the metal ion receptor was designed. The capability of the prepared probe to detect metal ions was evaluated by the changes in its emission intensity. The probe demonstrated a considerable emission enhancement (ca. 110-fold) in the presence of Al3+ in MeCN with high selectivity and sensitivity. Furthermore, the considerably 'off-on' fluorescence response concomitantly led to the apparent color change from colorless to brilliant yellow, which could also be identified by naked eye easily under 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; Koçak, Ahmet; Yılmaz, 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 'Naked-eye' detection of F- ions by two novel colorimetric receptors(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Erdemir, Serkan; Kocyigit, Ozcan; Alici, Onder; Malkondu, SaitTwo novel colorimetric receptors, S1 and S2, linked to one or two nitrophenylurea groups were synthesized in good yields, characterized and their chromogenic properties investigated towards various anions (F-, Cl-, Br-, I-, NO3-, AcO-, ClO4-, HSO4-, and H2PO4-) by UV-vis and H-1 NMR techniques. The receptors, effectively and selectively, recognized and distinguished the biologically important F- from other anions such as Cl-, Br-, I- etc. in CH3CN. This selectivity could be easily observed by the naked eye, indicating that receptors S1 and S2 are potential colorimetric sensors for fluoride ion. (c) 2012 Elsevier Ltd. All rights reserved.Öğe A novel "turn on" fluorescent sensor based on hydroxy-triphenylamine for Zn2+ and Cd2+ ions in MeCN(ELSEVIER SCIENCE SA, 2013) Erdemir, Serkan; Malkondu, SaitA novel easily available turn-on fluorescent sensor based on a triphenylamine-aminophenol conjugate( TAP) was synthesized, and characterized by combination of H-1, C-13, APT, COSY NMR, FTIR, elemental analysis, and UV-vis spectral data. TAP showed effectively selective and sensitive recognition toward Zn2+ and Cd2+ ions in CH3CN over other cations tested with remarkably enhanced fluorescent intensities. (C) 2013 Elsevier B. V. All rights reserved.Öğe Novel "turn on" fluorescent sensors based on anthracene and carbazone units for Cu (II) ion in CH3CN-H2O(ELSEVIER SCIENCE BV, 2015) Erdemir, Serkan; Malkondu, SaitTwo novel anthracene-based receptors containing Schiff base and urea groups (AOC and ATC) were synthesized in one step and full characterized. The optical properties of receptors AOC and ATC towards metal ions were investigated by UV-visible and fluorescence spectroscopy. It was found that both receptors AOC and ATC show highly selectivity towards Cu2+ over other 17 metal ions in CH3CN-H2O (9/1, v/v). (C) 2014 Elsevier B.V. All rights reserved.Öğe A novel colorimetric and fluorescent sensor based on calix[4]arene possessing triphenylamine units(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Erdemir, Serkan; Malkondu, Sait; Kocyigit, Ozcan; Alici, OnderA novel colorimetric and fluorometric calix[4]arene probe (CTP) bearing triphenylamine units was synthesized in good yield and characterized by combination of H-1, C-13, APT, COSY, FTIR, HRMS, and UV-vis spectral data. Ion-binding studies of CTP were investigated in acetonitrile with a wide range of cations and anions and the recognition process was monitored by luminescence, UV-vis and H-1 NMR spectral changes. CTP exhibited naked eye detection for Hg2+ ion. Also it showed a significant fluorescence quenching towards F- ion. (C) 2013 Elsevier B.V. All rights reserved.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 A novel perylene-bisimide dye as "turn on" fluorescent sensor for Hg2+ ion found in DMF/H2O(ELSEVIER SCI LTD, 2015) Malkondu, Sait; Erdemir, SerkanA highly efficient and selective perylene-bisimide sensor bearing thiophene units as the metal ion receptor is reported for the detection of Hg2+ ion. This sensor displays a rapid and highly selective "turn-on" response based on photoinduced electron transfer (PET) mechanism. Fluorescence enhancement by factors 20 times is achieved upon selective interaction with Hg2+ ion over other metal ions in aqueous solutions. (C) 2014 Elsevier Ltd. All rights reserved.Öğe O-alkylation of pyridine aldo- and ketoximes with dihalohydrins under phase-transfer conditions(TAYLOR & FRANCIS INC, 2007) Kocak, Abmet; Kurbanli, Sultan; Malkondu, SaitPhase-transfer-catalyzed alkylation of (E)-pyridine aldo- and (E)-ketoximes with dihalohydrins in the benzene (or DMSO)/10% aq. NaOH system in the presence of tetradecylammonium bromide proceeds regiospecifically to afford the corresponding O-halohydrins in good yields. In this study, first O-halohydrin derivatives were converted into glycidyl ether derivatives, and then a new series of amino alcohols were synthesized by the condensation of amines with these glycidyl ethers.Öğe A reaction-based approach for fluorescence sensing of fluoride through cyclization of an O-acyl pyrene amidoxime derivative(ELSEVIER SCIENCE SA, 2018) Malkondu, Sait; Altınkaya, Neslihan; Erdemir, Serkan; Koçak, AhmetA novel reaction-based O-acyl pyrene amidoxime derivative was easily synthesized from pyrene-1-carbaldehyde in three step and fully characterized. The sensing ability of the receptor towards various anions were investigated. The receptor exhibited distinct fluorescent behavior by a 45-fold increase in the emission intensity upon reacting with fluoride. The fluoride-induced cyclization reaction of the receptor led to formation of a highly fluorescent pyrene 1,2,4-oxadiazole derivative. However, other anions such as Cl-, Br-, I-, AcO-, NO3-, ClO4-, H2PO4- and HSO4- could not exhibit a remarkable increase in emission intensity. The fluorescence quenching of the receptor was explained by photoinduced electron transfer mechanism. The suppressing of photoinduced electron transfer, which was triggered by cyclization reaction between O-acyl amidoxime moiety and fluoride, led to an off-on type blue emission output. Fluoride could be detected with the present receptor up to a lower concentration limit down to 1.36 mu M. The fluorescence response of the receptor was rationalized by time-dependent density function theory calculations. Moreover, a practical application showed that the receptor could be exploited as a test paper in the fluorescence detecting for fluoride in water samples.Öğe A simple triazole-based "turn on" fluorescent sensor for Al3+ ion in MeCN-H2O and F- ion in MeCN(ELSEVIER, 2015) Erdemir, Serkan; Malkondu, SaitA novel fluorescent sensor N-((2-hydroxynaphthalen)-1-yl)methylene)-1H-1,2,4-triazole-3-carbohydrazide (NTA), based on triazole was synthesized in two facile steps, characterized systematically and used as a turn-on fluorescent sensor for both Al3+ and F-. The fluorescence spectra changes showed that NTA is highly selective for Al3+ over other metal ions in MeCN-H2O solution. The receptor NTA could also sense F- selectively in MeCN. The complexation properties of receptor NTA with Al3+ and F- ions were observed by H-1 NMR titration experiments. (C) 2014 Elsevier B.V. All rights reserved.Öğe Sistein Tayini İçin Yeni Bir Algılayıcı Molekülün Sentezi ve Karakterizasyonu(Selçuk Üniversitesi, 2022) Malkondu, Sait; Erdemir, SerkanSistein canlı organizmada önemli rolleri olan tiyol grubu içeren bir amino asittir. Dolayısıyla sistein varlığının ve miktarının tespit edilmesi araştırmacıların ilgilendiği konuların başında gelmektedir. Bu çalışmada, sisteini ESIPT mekanizmasına dayalı fluoresans metodu ile tayin etmek amacı ile benzotiyazol temelli yeni bir algılayıcı molekül tasarlanmıştır. Hedef algılayıcının molekül yapısı FT-IR, NMR ve MALDI-TOF (Matriks aracılı lazer dezorpsiyon iyonizasyon uçuş zamanı) kütle spektrokopisi gibi metotlarla aydınlatılmıştır. Ayrıca, algılayıcı ve sistein arasındaki etkileşim mekanizması teorik hesaplamalar aracılığıyla incelenmiştir.Öğe Sübstitüe taç eter ihtiva eden kitosanların sentezi(Selçuk Üniversitesi Fen Bilimleri Enstitüsü, 2006) Malkondu, Sait; Koçak, AhmetKitin, kabuklu deniz ürünlerinin kabuklarında bol bulunan doğal bir polisakkarittir. Selülozdan sonra doğada en bol bulunan biyopolimerdir. Kimyasal olarak kitin poli[β-(1â 4)-N-asetil-D-glukozamin]'dir. Kitosan ise kitinin alkali deasetilasyonu ile hazırlanır ve yapısı poli[β-(1â 4)-D-glukozamin]'dir. Kitosanın tarımda tohum kaplaması ve dondan koruma, su arıtımında koku giderici, gıdada anti-kolestrol katkı maddesi gibi birçok kullanımı bulunmaktadır. Dolayısıyla bu çalışmanın amacı yeni kitosan türevleri hazırlamaktır. Öncelikle, farklı halka büyüklüğü olan aza-taç eterler Williamson tipi eter sentezi ile elde edildi. Bu ligandların fenil grupları Vilsmeier-Haack formilasyonu ile fonksiyonlandırıldı. Yapıları IR ve 1H NMR spektroskopileri ve elementel analiz ile karakterize edildi. Kitosan ile aza-taç eterlerin Schiff baz reaksiyonundan N-Schiff baz tipi kitosan aza-taç eterleri hazırlandı. Elde edilen kitosan türevleri NaBH4 ile indirgenerek N-sekonder amino tipi kitosan aza-taç eterleri hazırlandı. Yeni kitosan türevlerinin yapıları IR spektroskopisi ve elementel analiz ile aydınlatıldı.Öğe Synthesis of a novel calix[4]azacrown ionophore and its extraction ability toward Cr(VI)(SPRINGER, 2013) Özcan, Fatih; Malkondu, Sait; Koçak, Ahmet; Koçak, Nuriye; Yılmaz, MustafaThe present study describes the synthesis of a novel extractant p-tert-butyl-calix[4]azacrown ionophore (5) and evaluation of its extraction capability toward dichromate ion from aqueous solution. At first, p-tert-butyl-calix[4]azacrown ionophore (5) has been synthesized from the condensation of p-tert-butyl-calix[4]arene diamine (3) with N-(4-formylphenyl)-aza-15-crown-5 (4). The studies regarding the removal of dichromate ion from the aqueous solutions have been carried out in the liquid-liquid extraction systems. The extraction results showed that p-tert-butyl-calix[4]azacrown derivative (5) exhibited generally higher affinity towards dichromate ion than both 3 and 4 at all studied pHs.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.
