Person: ÖZKAYA, ALİ RIZA
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ÖZKAYA
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ALİ RIZA
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Publication Open Access Fluorescent vic-dioxime-type ligand and its mono- and dinuclear complexes: The preparation, spectroscopy, and electrochemistry of its various complexes(ELSEVIER SCI LTD, 2008-01) ÖZKAYA, ALİ RIZA; Oezer, Metin; Kandaz, Mehmet; Oezkaya, Ali Riza; Bulut, Mustafa; Gueney, OrhanA new coumarin functionalized vic-dioxime, S,S-bis-[4-methylcoumarinyl]-dithioglyoxime (LH2), and its soluble mono- and dinuclear complexes [nickel(II), copper(II), cobalt(II), and uranyl(II)] have been reported. The fluorescent properties of the ligand and its complexes are due to the 7-mercapto-4-methylcoumarin fluorophore, which is conjugated with vic-dioxime that functions as the MN4 core. Fluorescence spectra of the probe showed a clear shift in excitation wavelength maxima upon metal binding indicating its potential use as ratio-metric metal indicator. The fluorescence of complexes was found to be highly sensitive to both polarity and protic character of the solvent used. Both mononuclear (LH)(2)M (M = Ni, Cu and Co) and homodinuclear (LH)(2)(UO2)(2)(OH)(2)) complexes have been obtained with the metal ligand ratios of 1:2 and 2:2, respectively. The characterizations of all newly synthesized compounds were made by elemental analysis, H-1 NMR, FT-IR, UV-vis, and mass (LSI-MS) data. The electrochemical investigation of the Ni(II), Cu(II), Co(II) and UO2(II) Complexes in comparison with the ligand involving oxime and coumarin moieties enabled us to identify metal-, oxime- and coumarin-based signals. (C) 2006 Elsevier Ltd. All rights reserved.Publication Metadata only Electrochemical, spectroelectrochemical, electrocatalytic oxygen reducing, and heavy metal ion sensing properties of novel tetrakis-[4-((2, 8-bis (trifluoromethyl) quinolin-4-yl) oxyl)] substituted metallophthalocyanines(ELSEVIER, 2022) ÖZKAYA, ALİ RIZA; Daban, Nese; Orman, Efe Baturhan; Meyanci, Lale; Altindal, Ahmet; Ozer, Metin; Ozkaya, Ali RizaNovel tetrakis-[4-((2,8-bis(trifluoromethyl)quinolin-4-yl)oxyl)] substituted phthalocyanine complexes were obtained by the tetramerization reaction of corresponding phthalonitrile derivative with appropriate metal salts under determined conditions. The structures of the complexes were clarified by elemental analysis, fourier transform infrared, ultraviolet-visible and matrix-assisted laser desorption ionization time-of-flight mass spectroscopic methods. The redox properties of zinc, cobalt, and iron phthalocyanines were investigated by voltammetric and colorimetry supported in situ spectroelectrochemical measurements in non-aqueous solution medium. The metal and phthalocyanine ring based redox processes were observed to be associated with distinct spectral and color changes and affected by the presence of molecular oxygen in the medium. Furthermore, oxygen interaction measurements performed during the oxygenation of de-aerated electrolyte solution suggested that the iron phthalocyanine complex possesses oxygen binding capability and has the tendency of forming mu-oxo-dimer complexes and thus, displaying electrocatalytic activity for oxygen reduction reaction. Electrocatalytic oxygen reducing performances of the complexes were investigated in a medium similar to direct methanol or polymer electrolyte membraned fuel-cell working conditions and compared in detail. Iron(II) phthalocyanine complex appeared as suitable electrocatalyst for both polymer electrolyte membraned and direct methanol fuel cells with high catalytic performance towards oxygen reduction and high tolerance to methanol, respectively. The metallophthalocyanines modified quartz crystal microbalance sensors were designed to detect divalent heavy metal ions (cobalt(II), cadmium(II), cupper(II), and zinc(II)) in water samples. Frequency shift measurements of the complexes showed that the possibility of the use of iron(II) phthalocyanine as a novel cadmium(II) ion sensing material, owing to its high sensitivity, reversibility, stability, and the possibility to operate at room temperature. (c) 2021 Elsevier B.V. All rights reserved.Publication Metadata only Communication-High-Performance and Non-Precious Bifunctional Oxygen Electrocatalysis with Binuclear Ball-Type Phthalocyanine Based Complexes for Zinc-Air Batteries(ELECTROCHEMICAL SOC INC, 2016) ÖZKAYA, ALİ RIZA; Ozen, Umit Ergin; Dogan, Elvan; Ozer, Metin; Bekaroglu, Ozer; Ozkaya, Ali RizaIn this study, the electrocatalytic activities and zinc-air battery performances of newly synthesized 4,4'-{(diphenylmethylene) bis(4,1-phenylene)bis(oxy)}-bridged binuclear ball-type iron(II), cobalt(II) and zinc(II) phthalocyanine, M2Pc2 complexes were investigated. Electrochemical measurements indicated that Fe2Pc2 complex is a good alternate to Pt/C catalyst. (C) 2016 The Electrochemical Society. All rights reserved.Publication Metadata only Synthesis, characterization and some properties of novel bis(pentafluorophenyl)methoxyl substituted metal free and metallophthalocyanines(PERGAMON-ELSEVIER SCIENCE LTD, 2006) ÖZKAYA, ALİ RIZA; Ozer, Metin; Altindal, Ahmet; Ozkaya, Ali Riza; Bulut, Mustafa; Bekaroglu, OzerThe preparation of some new tetrakis[bis(pentafluorophenyl)methoxyl] substituted metal free and metalloplithalocyanine (MPcs) complexes were achieved by the tetramerization of 4-[bis(pentafluorophenyl)methoxy]phthalonitrile with Li metal in pentan-1-ol or metal [Co(II) or Zn(II)] acetates in DMAE, respectively. The structures of the target compounds were confirmed by elemental analysis, IR, UV-vis, H-1 NNIR, F-19 NMR and mass spectroscopic methods. MPcs are soluble only in strong and medium polar solvents while the metal free one is soluble in weakly, medium and strong polar solvents. The temperature and frequency dependence of the electrical conductivities were studied on spin coated films of the compounds using dc and impedance spectroscopy techniques in the frequency range from 40 to 10(5) Hz and within the temperature range from 290 to 440 K. The temperature dependence of the exponent s and conductivity, sigma(ac), were completely in agreement with the prediction of the hopping model. The redox properties of the complexes were determined by cyclic voltammetry. The nature of the redox processes was also confirmed using spectroelectrochemcal measurements. (c) 2006 Elsevier Ltd. All rights reserved.Publication Metadata only Novel tetrakis 4-(hydroxymethyl)-2,6-dimethoxyphenoxyl substituted metallophthalocyanines: Synthesis, electrochemical redox, electrocatalytic oxygen reducing, and volatile organic compounds sensing and adsorption properties(ELSEVIER SCI LTD, 2018) ÖZKAYA, ALİ RIZA; Gunay, Ipek; Orman, Efe Baturhan; Altindal, Ahmet; Salih, Bekir; Ozer, Metin; Ozkaya, Ali RizaNovel tetrakis [(4-(hydroxymethyl)-2,6-dimethoxyphenoxyl)] substituted zinc(II), cobalt(II) and iron(II) phthalocyanines were synthesized by the reaction of (4-(hydroxymethyl)-2,6-dimethoxyphenoxy)phthalonitrile with suitable metal salts in 2-N, N-dimethylaminoethanol. The phthalonitrile ligand was prepared from 4-hydroxy-3,5-dimethoxy benzyl alcohol and 4-nitrophthalonitrile using potassium carbonate as catalyst in N,N-dimethylformamide at 50 degrees C. The structural characterization of the compounds was carried out by elemental analysis, FTIR, UV-vis and MALDI-TOF Mass spectroscopic methods. Electron transfer properties and electrocatalytic oxygen reducing performances of the compounds were also investigated by electrochemical, in situ spectroelectrochemical and in situ electrocolorimetric measurements. Electrochemical, in situ spectroelectrochemical, and in situ electrocolorimetric measurements showed that rich redox behavior of the complexes leads to their high electrocatalytic activity for oxygen reduction and net electrocolorimetric changes suitable for electrochromic applications. Phthalocyanine central metal ion effect on the sensing properties and the adsorption kinetics of four main groups of volatile organic compounds (alkanes, alcohols, chlorinated hydrocarbons and amines) onto these novel compounds were also examined by three different models. While the sensitivity of the sensors was strongly dependent on the nature of the metal ion, no considerable effect was observed on the adsorption kinetics. The evaluation of the kinetics of adsorption processes with respect to three different models showed that pseudo second order rate equation best describes the adsorption of alcohols and chlorinated hydrocarbons while the adsorption of alkanes and amines on these compounds can be represented by Elovich equation.Publication Metadata only Electrocatalytic Activity of Novel Ball-Type Metallophthalocyanines with Trifluoro Methyl Linkages in Oxygen Reduction Reaction and Application as Zn-Air Battery Cathode Catalyst(PERGAMON-ELSEVIER SCIENCE LTD, 2017) ÖZKAYA, ALİ RIZA; Kocyigit, Nilufer; Ozen, Umit Ergin; Ozer, Metin; Salih, Bekir; Ozkaya, Ali Riza; Bekaroglu, OzerA new series of functional compounds, (((perfluoropropane-2,2-diyl) bis (4, 1-phenylene)) bis (oxy))bridged ball-type metal-free and zinc(II), cobalt (II) and iron (II) metallophthalocyanines, behaving as the air catalyst in zinc-air batteries have been developed, and characterized with common spectroscopic methods. The catalyst composites were characterized by scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDS), and energy dispersive elemental mapping (EDS mapping). The catalytic activites of the dimeric type complexes on oxygen reduction reaction (ORR) have been evaluated by static and dynamic voltammetric techniques. In particular, iron (II) complex displayed spectacular catalytic activity with slightly more positive half-wave potential than that of the commercial Pt/C for ORR in alkaline media, mainly due to its distinctive cofacial molecular structure with dual redox-active metal centers. The electrocatalytic performance tests, carried out in a homemade Zn-air battery prototype, suggested that this complex can be used as an efficient ORR catalyst in this type of batteries. (C) 2017 Elsevier Ltd. All rights reserved.Publication Open Access Ball-type supramolecular metallophthalocyanines with eight perfluorodecyl units: chemosensors for SO2 and electrocatalysts for oxygen reduction(ROYAL SOC CHEMISTRY, 2009) ÖZKAYA, ALİ RIZA; Ozer, Metin; Altindal, Ahmet; Ozkaya, Ali Riza; Bekaroglu, OezerHeptadecafluorodecyl-substituted cofacial or ball-type bis-metallophthalocyanines (BTMPcs) have been prepared. The redox properties of the complexes and their catalytic activities for oxygen reduction were studied. The occurrence of stepwise one-electron redox processes during the voltammetric measurements in solution suggested the formation of stable mixed-valence species of the complexes, as a result of the intramolecular interactions between two cofacial Pc units. The ball-type Co(II) complex displayed excellent catalytic activity for oxygen reduction which is probably due to the rigid cofacial structure involving two redox-active metal centers, which are capable of binding O-2. do and ac conduction properties of BTMPcs [M = Co(II) 3 and Cu(II) 4]thin films have been investigated in the frequency range of 40 to 10(5) Hz and temperature 290-440 K. The do results showed an activated conductivity dependence on temperature for all films. The analysis of the obtained data showed that the correlated barrier hopping (CBH) model is the dominant conduction mechanism for electron transport in the films. The gas sensing properties of the films for SO2 were also investigated over the same temperature range. Although a very high response to SO2 gas has been obtained for the film of 3 at room temperature, the film of 4 was not sensitive to the same gases.Publication Metadata only Synthesis, characterization, and electrical, electrochemical and gas sensing properties of a novel cyclic borazine derivative containing three phthalocyaninato zinc(II) macrocycles(ELSEVIER SCIENCE SA, 2005) ÖZKAYA, ALİ RIZA; Ozer, M; Altindal, A; Ozkaya, AR; Bulut, M; Bekaroglu, OA novel borazine derivative of trinuclear phthalocyanine has been prepared by following the multistep reactions of unsymmetrically substituted phthalocyanines. 4-(4-Amino-3-nitrophenoxy)phthalonitrile (3) which is one of the precursor molecules of the phthalocyanine was obtained from 4-nitrophthalonitrile (1) and 4-amino-3-nitrophenol (2) with K2CO3 in DMF at 50 degrees C. The zinc(II) phthalocyanine (5) containing an unsymmetrical substituted 4-aniino-3-nitrophenoxy group was synthesized by statistical condensation of two different phthalonitriles. 4-(4-Amino-3-nitrophenoxy)phthalonitrile (3) and 4,5-bis(hexylthio)phthalonitrile (4) were cyclotetramerized with zinc acetate in DMF at 170-180 degrees C to yield 2-(4-amino-3-nitrophenoxy)-9,10,16,17,23,24-hexa(hexylthio)phthalocyanine zinc(II) complex (5), which was then separated by column chromatography on silica gel. The unsymmetrically substituted compound was reduced to the diamine form (6) using hydrazine hydrate in the presence of Pd/C catalyst, and the product was purified with chromatographic separation. Compound 6 was then reacted with triisopropoxyborane in refluxing xylene to give 5H,12H,19H-tris[2-(3,4-diaminophenoxy)-9,10,16,17,23,24-hexa(hexylthio)phthalocyaninato zinc(II) diazaborolo] borazine (7). The resulting product was purified by column chromatography on silica gel. All the target unsymmetrical phthalocyanines and borazine derivative were characterized by elemental analysis, IR, UV-vis, and H-1 NMR. Boron and zinc(II) percents in 7 were quantified with ICP-MS. Impedance spectroscopy and dc measurements were performed on spin coated 5-7 films as a function of temperature (293-400 K). The dc results showed an activated conductivity dependence on temperature. The ac results gave a temperature dependent frequency exponent s. The results were compared with the prediction of the Quantum Mechanical Tunelling and Correlated Barrier Hopping models. The ac conductivity of the films was well represented by the form A omega(s). Gas sensing properties of the films for the volatile organic compounds (VOCs) (chloroform, acetone, carbontetrachloride and ammonia) were also investigated in the temperature range from 293 to 400 K. The operating temperature had a considerable effect on sensing characteristics. Maximum sensitivity to VOCs were observed at room temperature for all films. Cyclic voltammetry of compounds 6 and 7 in solution indicated that these compounds have similar voltammetric behaviour. (C) 2005 Elsevier B.V. All rights reserved.Publication Metadata only Electrocatalytic activity, methanol tolerance and stability of perfluoroalkyl-substituted mononuclear, and ball-type dinuclear cobalt phthalocyanines for oxygen reduction in acidic medium(ROYAL SOC CHEMISTRY, 2009) ÖZKAYA, ALİ RIZA; Koc, I.; Oezer, M.; Oezkaya, A. R.; Bekaroglu, O.Electrocatalytic activitiy, methanol tolerance and stability of three phthalocyanine (Pc) complexes (a heptadecafluorononyl-substituted mononuclear CoPc 1, a pentaerythritol-bridged ball-type dinuclear Co2Pc2 2 and a heptadecafluorodecyl-substituted, pentaerythritol-bridged ball-type dinuclear Co2Pc2 3) and the performance of dual catalysts of 2/Pt and 3/Pt, dispersed on a high surface area carbon substrate, Vulcan XC-72 (VC) and Nafion (Nf), towards oxygen reduction (OR) were investigated and compared by surface cyclic voltammetry, rotating disk electrode, rotating ring-disk electrode and chronoamperometry experiments in acidic medium. The VC/Nf/3 modified glassy carbon electrode showed much higher catalytic performance, compared to VC/Nf/2 and VC/Nf/1 modified ones. The long term stability of the VC/Nf/3 catalyst in acidic medium was better than that of VC/Nf/2. It was found that the VC/Nf/1, VC/Nf/2 and VC/Nf/3 catalysts are nearly insensitive to the presence of methanol. In the presence of 1 M methanol in the electrolyte, the catalytic performances of 2- and 3-based catalysts were much better than that of the Pt-based one. Thus, it was shown that the VC/Nf/2-Pt and VC/Nf/3-Pt dual catalysts can be good alternatives to VC/Nf/Pt as cathode catalysts in direct methanol fuel cells. Moreover, in the absence of methanol, the mixing of 3 with Pt resulted in the enhancement of catalytic activity for OR, when compared to 3 and even Pt in the high overpotentials region.Publication Metadata only Synthesis, characterization, OFET and electrochemical properties of novel dimeric metallophthalocyanines(ROYAL SOC CHEMISTRY, 2013) ÖZKAYA, ALİ RIZA; Ozer, Lale Meyanci; Ozer, Metin; Altindal, Ahmet; Ozkaya, Ali Riza; Salih, Bekir; Bekaroglu, OzerThe synthesis of 4,4'-[6,6'-methylenebis (2-(2-(3,4-dicyanophenoxy)-5-methylbenzyl)-4-methyl-6,1-phenylene)] bis (oxy) diphthalonitrile 1 was achieved starting from 4-nitrophthalonitrile and 6,6'-methylenebis( 2-(2-hydroxy-5-methylbenzyl)-4-methylphenol in DMF at 50 degrees C by the catalysis of K2CO3 under argon. The corresponding dimeric metallophthalocyanines (Zn2Pc2 2 and Co2Pc2 3) were tetramerized in dimethylaminoethanol with the appropriate metal salt. Newly synthesized compounds were characterized by elemental analysis, UV-vis, FT-IR (ATR), MALDI-TOF mass and H-1-NMR spectroscopy techniques. The electrochemical properties of the complexes were examined by cyclic voltammetry, differential pulse voltammetry, controlled potential coulometry and in situ spectroelectrochemistry in nonaqueous media. The results showed that while there is considerable weak interactions between the two metal phthalocyanine units in dimeric zinc phthalocyanine, these interactions in dimeric cobalt phthalocyanine is remarkable. The catalytic performances of dimeric cobalt phthalocyanine in the reduction of oxygen in a medium similar to the working conditions of the polymer electrolyte membrane fuel-cells were found to be much higher than that of dinuclear zinc phthalocyanine. Solution-processed films of the complexes were utilized as an active semiconducting layer in the fabrication of organic field-effect transistors (OFETs) in the bottom-gate configurations. The output characteristics of the resulting p-type OFET devices were investigated to evaluate the performances such as the field effect mobility (mu F). A relatively high field effect mobility of 7.3 x 10(-3) cm(2) V-1 s(-1) was observed for dimeric cobalt phthalocyanine.