Person: ÖZKAYA, ALİ RIZA
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ÖZKAYA
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ALİ RIZA
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Publication Metadata only Synthesis, characterization, and electrochemical, and electrical measurements of novel 4,4 '-isopropylidendioxydiphenyl bridged bis and cofacial bis-metallophthalocyanines (Zn, Co)(PERGAMON-ELSEVIER SCIENCE LTD, 2008) ÖZKAYA, ALİ RIZA; Canlica, Mevlude; Altindal, Ahmet; Oezkaya, Ali Riza; Salih, Bekir; Bekaroglu, Oezer4,4'-Isopropylidendioxydiphenyl bridged bis-metallophthalocyanines Zn(II) (5) and Co(II) (6) were synthesized from the compound 4,4'-isopropylidendioxydiphthalonitrile (3) and 4,5-bis(hexylthio)phthalonitrile (4). The new cofacial bis-phthalocyanines Zn(II) (7) and Co(II) (8) were synthesized from the corresponding 3 which can be obtained by the reaction of 4,4'-isopropylidendiphenol (1) with 4-nitrophthalonitrile (2). These complexes have been characterized by elemental analysis, UV/Vis, FT-IR, H-1 NMR and MALDI-TOF mass spectroscopies. The electrochemical properties of the complexes were examined by cyclic voltammetry, differential pulse voltammetry and controlled potential coulometry in nonaqueous media. Electrochemical results showed that while there is not any considerable interaction between the two phthalocyanine rings in bisphthalocyanine complexes 5 and 6, the splitting of the molecular orbitals occurs as a result of the strong interaction between the phthalocyanine rings in cofacial complexes 7 and 8. Measurements of capacitance showed a well defined decrease with increasing frequency and an increase with increasing temperature at lower frequencies. (C) 2008 Elsevier Ltd. All rights reserved.Publication Metadata only Electrical and electrochemical properties of double-decker Lu(III) and Eu(III) phthalocyanines with four imidazoles and N-alkylated imidazoles(PERGAMON-ELSEVIER SCIENCE LTD, 2012) ÖZKAYA, ALİ RIZA; Yabas, Ebru; Sulu, Mustafa; Dumludag, Fatih; Ozkaya, Ali Riza; Salih, Bekir; Bekaroglu, OzerImidazole tetrasubstituted double-decker Lu(III) (2) and Eu(III) (3) phthalocyanines have been synthesized by heating 4[(4,5-diphenyl-1H-imidazole)-2-yl-thio]phthalonitrile (1) with Lu(OAc)(3)center dot nH(2)O or Eu(OAc)(3)center dot nH(2)O in n-hexanol in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, respectively. N-alkylated imidazole tetrasubstituted double-decker Lu(III) (4) and Eu(III) (5) phthalocyanines have been synthesized by the reaction of compounds 2 and 3 with hexyl bromide, in DMF in the presence of K2CO3, respectively. The new compounds were obtained in sufficient purity after successive washing with different solvents and were characterized by elemental analysis and H-1 NMR, UV-Vis, IR, MALDI-TOF mass and electron spin resonance spectra. Electrical measurements of the 2-5 performed in a vacuum (<2 x 10(-3) mbar) in the dark between the temperatures of 295 and 523 K suggest that their films show semi-conductor behavior. It was found that, in general, sigma(d.c.) (4) > sigma(d.c.) (2) in the temperature range 295-458 K, and sigma(d.c). (5) > sigma(d.c.) (3) in the measured temperature range. Depressed semi-circles with different radii at high temperatures in impedance spectra measurements indicated deviation from the Debye dispersion relation. The redox behaviors of the compounds were also investigated by voltammetry and in situ spectroelectrochemistry in dimethylsulfoxide with tetrabutylammonium perchlorate. (c) 2012 Elsevier Ltd. All rights reserved.Publication Metadata only Electrochemical, Electrocatalytic Dioxygen Reducing and Dielectric Relaxation Properties of Non-Peripheral Tetra-2,3-dihydro-1H-inden-5-yloxy Substituted Phthalocyanines(ELECTROCHEMICAL SOC INC, 2015) ÖZKAYA, ALİ RIZA; Orman, Efe Baturhan; Altun, Selcuk; Odabas, Zafer; Altindal, Ahmet; Ozkaya, Ali RizaNovel metal-free and metallophthalocyanines were synthesized by cyclotetramerization of 3-(2,3-dihydro-1H-inden-5-yloxy)phthalonitrile and characterized. The redox properties of these compounds were investigated by cyclic voltammetry, square-wave voltammetry, controlled-potential coulometry and in situ spectroelectrochemistry in dimethylsulfoxide and dichloromethane. The compounds displayed metal and/or phthalocyanine ring-based reduction and oxidation processes. The color changes associated with these redox processes and electrogenerated anionic and cationic redox species were recorded with in situ electrocolorimetric measurements. The electrocatalytic performances of the compounds toward oxygen reduction reaction having vital importance for fuel cell applications were determined by hydrodynamic rotating disk and bipotentiostatic rotating ring-disk voltammetry measurements. The Vulcan XC-72/Nf/FePc modified glassy carbon electrode showed much higher catalytic performance toward oxygen reduction than those of the other modified ones. Furthermore, the field dependence of dielectric response and the conductivity of the samples were measured as a function of frequency and temperature. Dielectric relaxation behaviors of the phthalocyanines were also investigated. The ITO/ZnPc/Au sample showed the highest value of epsilon'(omega) as compared to the other samples. The analysis of the real and imaginary parts of the dielectric permittivity with frequency was carried out assuming a distribution of relaxation times as well as the scaling behavior of the dielectric loss spectra. (C) 2015 The Electrochemical Society. All rights reserved.Publication Metadata only Novel peripherally substituted metal-free, zinc (II), and cobalt (II) phthalocyanines with 1,1 '-thiobis(2-napthol) and additional tetraphthalonitrile groups: Synthesis, aggregation behavior, electrochemical redox and electrocatalytic oxygen reducing properties(ELSEVIER SCIENCE SA, 2020) ÖZKAYA, ALİ RIZA; Orman, Efe Baturhan; Saglam, Meltem Betul; Ozkaya, Ali RizaNovel phthalocyanines containing only 1,1'-thiobis(2-napthol) groups or 1,1'-thiobis(2-napthol) and phthalonitrile groups at peripheral positions were prepared by nucleophilic displacement reaction through cyclotetramerization of phthalonitrile derivatives, benzo[b]dinaphtho [1,2-h:2',1'-e] [1,4,7] dioxathionine-5,6-dicarbonitrile and 4,4'- [thiobis(naphthalene-1,2-diyloxy)] diphthalonitrile in penthanol. The aggregation tendencies and electrochemical redox properties of all phthalocyanines were investigated on the basis of central metal, solvent medium and subsituent effects, using UV-Vis spectral and classical electroanalytical techniques. The compounds exhibited metal-and/or phthalocyanine ring-based electron transfer processes which were coupled by distinct spectral changes and thus, net color transformations pointing out the possibility for their usage in electrochromic applications. Furthermore, remarkable enhancement in catalytic activity towards oxygen reduction and high tolerance to methanol during this reaction have been observed when the zinc (II) or 2H center was replaced with cobalt (II).Publication Metadata only Synthesis, characterisation and electrochemistry of derivatisable novel -tetra 7-oxycoumarin-3-carboxylate-substituted metallophthalocyanines(TAYLOR & FRANCIS LTD, 2011) ÖZKAYA, ALİ RIZA; Dur, Eyup; Ozkaya, Ali Riza; Bulut, MustafaNovel -tetra-substituted metallophthalocyanines (ZnPc (3), CoPc (4), CuPc (5) and NiPc (6)) have been synthesised by cyclotetramerisation of a novel ligand, ethyl 7-(2,3-dicyanophenoxy)coumarin-3-carboxylate, with the relevant metal acetates. In addition, two derivatives of 3, slightly water-soluble tetrakis[7-oxycoumarin-3-carboxylic acid] phthalocyaninatozinc(II) and tetrakis[7-oxo-3-(ethyl piperidine-3-carboxlate)-coumarin]phthalocyaninatozinc(II), were prepared by its reaction with HCl (37%) and heating with ethyl 3-piperidinecarboxylate, respectively. The newly prepared compounds have been characterised by FT-IR, UV-vis, MALDI-TOF mass and 1H NMR spectroscopies. The redox behaviour of 3-6 was also investigated by voltammetry and in situ spectroelectrochemistry.Publication Metadata only Synthesis and electrochemical properties of crown ether functionalized coumarin substituted cobalt and copper phthalocyanines(ELSEVIER SCIENCE SA, 2011) ÖZKAYA, ALİ RIZA; Esenpinar, Aliye Asli; Ozkaya, Ali Riza; Bulut, MustafaThe synthesis of novel 6,7-[15-crown-5]-3-[p-(3,4-dicyanophenoxy)phenyl]coumarin (1)/6,7-[15-crown-5]-3-[p-(2,3-dicyanophenoxy)phenyl]coumarin (2) and their peripherally/non-peripherally cobalt and copper phthalocyanine complexes (3-6) have been prepared and characterized by elementel analysis, H-1-NMR, MALDI-TOF, FT-IR and UV-Vis spectral data. Fluorescence intensity changes of compound 1 and 2 have been determined by addition of Na+ or K+ ions at 25 degrees C in THF. The effect of substitution type on the redox and aggregation behaviour of the compounds was investigated by voltammetry and in situ spectroelectrochemistry. (C) 2011 Elsevier B.V. All rights reserved.Publication Metadata only H-type aggregation of functional metal ion sensing phthalocyanines: Synthesis, characterization and electrochemistry(PERGAMON-ELSEVIER SCIENCE LTD, 2010) ÖZKAYA, ALİ RIZA; Bilgicli, Ahmet T.; Yarasir, M. N.; Kandaz, Mehmet; Ozkaya, A. RizaWe report, in this study, the preparation and physical characterization of the peripherally functionalized ionophore ligand, 4,5-bis(6-hydroxyhexan-3ylthio)-1,2-dicyanobenzene (1) and its branched thioalcohol-substituted phthalocyanines, 2,3,7,8,12,13,17,18-octakis{6-hydroxyhexan-3-ylthio)-metal (II) or (III) phthalocyanines (M(Pc[SCH(C(3)H(7))(C(2)H(5)OH)](8)) {M = Pb(II) (2), Zn(II) (3), Cu(II) (4), Co(II) (5) and Mn(III), X = Cl(-) (6)) which can selectively bind soft-metal ions such as silver (I) and palladium (II). It was observed by means of UV-Vis absorption spectrophotometry that the aggregates formed lead to a low solubility of the phthalocyanines in protic solvents, such as low molecular alcohols. However, the addition of AgNO(3) and Na(2)PdCl(4) into a THF-MeOH solution of {M{Pc[SCH(C(3)H(7))(C(2)H(5)OH)](8)X) (M = Pb(II) (2), Zn(II) (3), Cu(II) (4), Co(II) (5) and Mn(III), X = Cl- (6)) induced optical changes, which indicated the formation of twisted H-type dimers (blue shift, face-to-face fashion) of (M(Pc[SCH(C3H7)(C2H5OH)18) complexes, bound by four PdCl(2) and AgNO(3) units in THF solution. Elemental analysis data, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS), FT-IR, (1)H, (13)C NMR, and UV-Vis spectral data were used as complementary techniques. Voltammetry and in situ spectroelectrochemistry of the complexes were performed on Pt in DMSO/TBAP. The first reduction and oxidation processes of 5 were found to be split due to the presence of facile equilibria between the species coordinated differently at axial positions. The Mn(III)Pc(-2)X(-) complex (6) displayed well-defined colour changes during its reduction processes. The redox behaviour of the Mn(III)Pc( -2)X- complex was observed to be affected significantly by the existence of oxygen in solution due to the formation of mu-oxo MnPc species, Mn(III)Pc-O-PcMn(III). This effect was clarified well by in situ spectroelectrochemical measurements. (C) 2010 Elsevier Ltd. All rights reserved.Publication Metadata only Electrocatalytic hydrogen evolution reaction with metallophthalocyanines modified with click electrochemistry(PERGAMON-ELSEVIER SCIENCE LTD, 2015) ÖZKAYA, ALİ RIZA; Akyuz, Duygu; Dincer, Hatice; Ozkaya, Ali Riza; Koca, AtifCobalt and zinc phthalocyanines bearing terminal alkyne groups (TA-CoPc and TA-ZnPc) were electrochemically characterized in order to determine their functionalities for practical usages as effective electrocatalysts. Observation of multi-electron and metal and/or ring based reduction reactions at low potentials indicated the worthy of these complexes as functional materials. Shifts of proton reduction potentials toward more positive values in solutions involving MPc indicated homogeneous electrocatalytic activities of the complexes for hydrogen evolution reaction (HER). For practical usage as heterogeneous electrocatalysts for HER, electrodes were constructed with a new electrode modification technique, click electrochemistry, with which TA-CoPc and TA-ZnPc complexes were bonded to azido functionalized polyaniline (PANI-N-3) electropolymerized on electrodes. The modified Glassy Carbon Electrode (GCE)/PANI-N-3/TA-CoPc and GCE/PANI-N-3/TA-ZnPc electrodes were characterized using voltammetric techniques and electrochemical impedance spectroscopy (EIS), then tested as heterogeneous electrocatalyst for HER. GCE/PANI-N-3/TA-CoPc electrodes especially decrease the over-potential of the bare electrode about 216 mV and increase the efficiency of the electrode about 32 fold at low pHs. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Publication Metadata only Electrochemical, Spectroelectrochemical, and Electrochromic Properties of Lanthanide Bis-Phthalocyanines(ELECTROCHEMICAL SOC INC, 2014) ÖZKAYA, ALİ RIZA; Orman, Efe Baturhan; Koca, Atif; Ozkaya, Ali Riza; Gurol, Ilke; Durmus, Mahmut; Ahsen, VefaVoltammetric, in-situ spectroelectrochemical, and in-situ electrocolorimetric characterization of octa-2,2,3,3-tetrafluoropropoxy-substituted lanthanide (III) bis-phthalocyanines [samarium(III) (SmPc2), europium (III) (EuPc2), gadolinium (III) (GdPc2), dysprosium( III) (DyPc2) and lutetium(III) (LuPc2)] were performed in solution and in the solid states as Langmuir-Blodgett (LB) films. The type of the central metal of the complexes slightly altered the potentials of the electron transfer reactions. Redox peaks shifted toward the negative potentials as a function of the decreasing metal ion size. All complexes gave three reduction and one oxidation reactions with in the whole potential window of the electrolyte system. Due to the p-p interaction of phthalocyanine rings around the lanthanide metal ions the complexes were easily reduced at even positive potentials. Assignments of the redox processes, spectra and color of the electrogenerated species of the complexes were determined with in-situ spectroelectrochemical, and in-situ electrocolorimetric measurements. Various colors recorded during the electron transfer reactions well reflected electrochromic characters of the complexes. For practical usage, LB thin films of the complexes were easily coated on the ITO electrodes and investigated as electrochromic materials. All complexes displayed three distinctive color alternatives as green, orange, and red for their different redox states. Electrochromic measurements indicated that the nature of the metal ions in the phthalocyanine cavity alters the basic electrochromic parameters of the complexes. LB films of DyPc2 and LuPc2 were especially found as ideal neutral and anodic coloring electrochromic materials with their short response times, and high optical and coulombic stabilities. (C) 2014 The Electrochemical Society. All rights reserved.Publication Metadata only Highly selective thioalcohol modified phthalocyanine sensors for Ag(I) and Pd(II) based on target induced J- and H-type aggregations: synthesis, electrochemistry and peripheral metal ion binding studies(ROYAL SOC CHEMISTRY, 2012) ÖZKAYA, ALİ RIZA; Bilgicli, Ahmet T.; Gunsel, Armagan; Kandaz, Mehmet; Ozkaya, A. RizaWe have described highly selective 1(4), 8(11), 15(18), 22(25)-(1-hydroxyhexan-3-ylthio)-phthalocyanine sensors, M{Pc[alpha-SCH(C3H7)(C2H5OH)](4)} (MPc(alpha-HHT)(4), where M = Zn(II) (2), Cu(II) (3) or Co(II) (4) and HHT: -SCH(C3H7)(C2H5OH)). The formation of S-M-S {S = sulfur; M = Ag(I) or Pd(II)} bonds on the periphery in the case of Ag(I) and Pd(II) metal ions induces H-or J-aggregation, respectively, which results in significant changes in the absorption of the B-and, in particular, the Q-band. The binding ratios of Ag(I) to the periphery of 2 and 3 were found to be ca. 2 : 1 and 3 : 2, respectively. On the other hand, the binding ratios of Pd(II) to the periphery of the same compounds were found to be 3 : 1 and 4 : 1. The fluorescence of 2 exhibited distinct changes in response to treatment with Ag(I) and Pd(II) ions in solution. The fluorescence spectra emission intensity of 2 was quenched upon titration with Ag(I) and Pd(II) and a new emission maximum was observed upon titration with Pd(II). FTIR, H-1-NMR, C-13-NMR, UV-vis, MALDI-TOF MS and elemental analysis data were used to characterize the novel compounds. Transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FE-SEM) were also used as complementary techniques to investigate the morphology and to image the interfacial aggregates of 2. The redox behaviours of the complexes were examined by voltammetry and in situ spectroelectrochemistry on Pt in a nonaqueous medium.
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