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 Open Access Tetrahydroxyphthalocyanine as a potential nonlinear optical material(2023-01-05) ÖZKAYA, ALİ RIZA; ORMAN, EFE BATURHAN; Işık Büyükekşi S., ORMAN E. B., KARATAY A., Selçuki N. A., ÖZKAYA A. R., ELMALI A., SALİH B., Şengül A.© 2022We have synthesized a new zinc(II)-phthalocyanine (ZnPc) incorporating hydroxyl groups at the peripheral positions. This new zinc(II)-tetra-hydroxyphthalocyanine (1) has been characterized by high-resolution MALDI TOF MS, UV-Vis, FT-IR (ATR), and 1H- and 13C-NMR techniques, and further by the electrochemical measurements. DFT and TD-DFT computations were performed to model plausible structure and also analyze the electronic structure and optical properties of 1. The effects of the polarity and hydrogen bonding ability of the hydroxyl substituents on the peripheral positions of 1 on the optical and electrochemical properties are reported in this study. The redox behavior of 1 in dimethyl sulfoxide (DMSO) was determined by voltammetry and colorimetry supported in situ spectroelectrochemistry. The nonlinear absorption and optical limiting (OL) properties of 1 were measured in tetrahydrofuran (THF) by utilizing the open aperture Z-scan technique with nanosecond pulses at 532 nm. The sample demonstrated good reverse saturable absorption and OL behaviors. The ultrafast pump-probe experiments revealed the intersystem crossing (ISC) mechanism (triplet-triplet transition) and the nonlinear absorption mechanism of the compound. The results indicate that this new phthalocyanine (1) can be considered a potential candidate for low-power OL applications.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 Open Access Electrochemical and in-situ spectroelectrochemical properties of novel (5-(tert-butyl)-2-((3,4-dicyanophenoxy)methyl)phenyl)methanolate substituted mononuclear metal phthalocyanines(2023-03-15) ORMAN, EFE BATURHAN; ODABAŞ, ZAFER; ÖZKAYA, ALİ RIZA; Şahin S., Akdağ Ö., ORMAN E. B., ODABAŞ Z., ÖZKAYA A. R.© 2022This work involves the synthesis and characterization of metallic (Co, Fe, Mn, Ni, Zn) ball-type phthalocyanine precursors by using novel 4,4′-(((4-(tert-butyl)-1,2-phenylene)bis-(methylene))bis(oxy))diphthalonitrile starting compound. The classical oxo-bridge in phthalocyanines was altered with the -OCH2- bridge first time for these ball-type phthalocyanine precursors, and the effects of this change on the chemical, physical and spectral features of phthalocyanine complexes were investigated, in the study. The redox properties of phthalocyanines were researched by electrochemical and in situ spectroelectrochemical measurements on a Pt working electrode in non-aqueous medium. The color changes involved in the redox processes were observed via in situ electrocolorimetric techniques. Electrochemical and UV–Vis spectral measurements exhibited that the compounds had reversible and serial one-electron reduction and oxidation processes. Furthermore, they also had nitrile reduction processes because of opened nitrile groups located at peripheral tails of the phthalocyanine complexes. The plentiful redox conducts of the complexes such as Pc ring based and/or central redox active metal-based reduction and oxidation reactions at low potentials showed that these complexes can be used as functional materials. Because of the apparent spectral and net color changes, the complexes are suitable for utilization in electrochromic devices. Moreover, their rich redox features are a sign of their high electrocatalytic activity for oxygen reduction.Publication Open Access Design of novel metal chalcogenide photoanodes supported with reduced graphene oxide for improvement of photoelectrochemical hydrogen evolution(2023-06-01) BUDAK, ÖZLEM; KARACA ALBAYRAK, FATMA; ÖZKAYA, ALİ RIZA; KOCA, ATIF; Neli Ö. U., BUDAK Ö., KARACA ALBAYRAK F., KESKİN B., ÖZKAYA A. R., KOCA A.Designing new photoanodes with high efficiency provides an effective route to develop photoelectrochemical hydrogen production. In this work, quaternary metal chalcogenides (CdZnMSSe (M: Ni, Cu, Mo)) and reduced graphene oxide- quaternary metal chalcogenide (RGO-CdZnMSSe) composite films are fabricated by simple one-step electrodeposition process. The photoanodes formed of quaternary metal chalcogenides and the incorporation of RGO in these composite films increase charge transfer capability and separation ability compared to cadmium-based photoanodes, leading to enhancement of the photoelectrochemical hydrogen production activity. A superior photocurrent response is recorded for RGO(0.25)-Cd0.8Zn0.2Ni0.2S0.2Se0.8 (5.34 mA cm−2 at 0.8 V vs RHE). In addition, the maximum ABPE value of RGO(0.25)-Cd0.8Zn0.2Ni0.2S0.2Se0.8 is determined as 1.95%. The achieved results offer a new insight into highly efficient next generation-photoanodes to convert solar energy to hydrogen.Publication Open Access Electrochemical, spectroelectrochemical, and electrocatalytic properties of novel soluble phthalocyanines containing peripheral thymoxy and chloride units(2023-03-01) ODABAŞ, ZAFER; ÖZKAYA, ALİ RIZA; Atajanov R., Huraibat B., ODABAŞ Z., ÖZKAYA A. R.© 2022 Elsevier B.V.Novel CoPc, CuPc, Fe(OAc)Pc and Mn(Cl)Pc were synthesized by using original 4-chloro-5-(2-isopropyl-5-methylphenoxy)phthalonitrile in order to investigate their potential redox applications suitable with their chemical and physical characteristics. The molecular structures of new compounds were determined with spectroscopic methods such as elemental analysis, FT-IR, UV–vis, NMR and MALDI TOF MS. Redox behaviours of Fe(OAc)Pc and Mn(Cl)Pc complexes have been probed by using diverse voltammetric techniques such as cyclic (CV) and square wave voltammetry (SWV). In addition, the colour alterations accompanying spectral changes were perused concurrently with electrocolorimetric measurements, and electrocatalytic efficiencies of the all compounds were perused in oxygen reduction reaction.