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 in-situ spectroelectrochemical properties of novel peripherally and non-peripherally 7-oxy-3-(3,4-dimethoxyphenyl) coumarin substituted phthalocyanines(ELSEVIER SCI LTD, 2019) ÖZKAYA, ALİ RIZA; Feridun, Seda Gureli; Orman, Efe Baturhan; Salan, Umit; Ozkaya, Ali Riza; Bulut, MustafaNovel metal-free (4 and 9), Zn(II) (5 and 10) and Co(II) (6 and 11) phthalocyanines (Pcs) bearing four 7-oxy-3(3,4-dimethoxyphenyl)coumarin (1) substituents at peripheral (13) and non-peripheral (a) positions have been prepared by cyclotetramerization reactions of 4-(3-(3,4-dimethoxyphenyl)coumarin-7-oxy)phthalonitrile (3) or 3-(3-(3,4-dimethoxy-phenyl)coumarin-7-oxy)phthalonitrile (8), respectively, in the presence of relevant metal acetate salts in N,N-dimethylaminoethanol. The compounds have been characterized by elemental analysis, FTIR, UV-Vis and MALDI-TOF mass spectroscopies. Thermal properties of the compounds were evaluated by thermogravimetric analysis and differential scanning calorimetry. Electrochemical redox properties of all compounds were investigated by voltammetric and in-situ spectroelectrochemical measurements in dimethylsulfoxide including tetrabutyl ammonium perchlorate as the supporting electrolyte. The metal-free and Zn(II)Pc compounds displayed Pc ring-based redox processes whereas both Pc ring-based and metal-based electron transfer processes were observed for Co(II)Pc complexes. H-aggregation tendency of peripherally substituted compounds was found to be much higher than that of non-peripherally substituted ones. It was observed that there have been systemmatic redox potential and aggregation behaviour differences between the peripherally and non-peripherally substituted Pc compounds. These differences were attributed to different sterical and conformational effects of these substitution patterns. In-situ spectroelectrochemical and in-situ electrocolorimetric measurements suggested that peripherally substituted Co(II)Pc is a multi-coloured chromophore material displaying distinct spectral and colour changes during the first reduction and oxidation processes, and thus, being suitable for electrochromic applications.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 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 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 Ag(I) and Pd(II) sensing, H- or J-aggregation and redox properties of metal-free, manganase(III) and gallium(III) phthalocyanines(ELSEVIER SCI LTD, 2014) ÖZKAYA, ALİ RIZA; Gunsel, Armagan; Bilgicli, Ahmet T.; Kandaz, Mehmet; Orman, Efe B.; Ozkaya, A. RizaH- or J-aggregation, Ag(I) and Pd(II) sensing and redox behaviours of novel a-substituted free-base (2), manganase(III) (3) and gallium(III) (4) phthalocyanines bearing 1-hydroxy hexane-3-ylthio moieties have been studied. H-1 NMR, FTIR, MALDI-TOF/MS, UV-Vis spectral and elemental data were used to characterize these new compounds. Upon addition of Ag(I), Pd(II), Mn(II), Co(II), Zn(II), Na(I), K(I) and Mg(II) ions to the solution of 2,3 and 4 in THF, only Ag(I), Pd(II) among them led to significant changes in their electronic absorption spectra, in particular, the Q- and the B-bands on the basis of donor acceptor interactions on the periphery in 2 and 3. Thus, in situ UV-Vis spectrotitration measurements suggested that 2 and 3 displayed high and reversible sensitivity towards Ag(I) and Pd(11) ions, as a result of the soft-metal responsive H- and J-aggregation behaviours. On the other hand, Ga(III)PcCl (4) with chlorine atoms at the axial positions and with large metal radii in the core did not show remarkable response to any ions. The binding ratio of 2 and 3 for Ag(I) was calculated as 1:1 and 1:2. AFM (Atomic Force Microscopy) was also used as complementary technique to investigate the morphology and to image the interfacial aggregates of 3. Compounds 2 and 4 showed ligand-based redox couples while 3 displayed well-defined ligand- and metal-based electrochromic processes. The existence of oxygen in solution was found to affect the redox behaviour of manganase phthalocyanine complex significantly, due to the formation of mu-oxo manganase phthalocyanine species. (C) 2013 Elsevier Ltd. All rights reserved.Publication Metadata only Synthesis, characterization, spectroscopic and electrochemical properties of phthalocyanines substituted with four 3-ferrocenyl-7-oxycoumarin moieties(ELSEVIER SCIENCE SA, 2011) ÖZKAYA, ALİ RIZA; Camur, Meryem; Esenpinar, A. Asli; Ozkaya, A. Riza; Bulut, MustafaThe synthesis, spectroscopic and electrochemical properties of the tetra-(3-ferrocenyl-7-oxycoumarin)substituted zinc (II) and cobalt (II) phthalocyanines (3 and 4) are reported for the first time. The synthesis of novel 3-ferrocenyl-7-hydroxycoumarin (1) was performed according to Perkin reaction, and the ligand, 7-(3,4-dicyanophenoxy)-3-ferrocenylcoumarin (2), was synthesized by the reaction of 3-ferrocenyl-7-hydroxycoumarin with 4-nitrophthalonitrile in the presence of K(2)CO(3) as the base in dry dimethylformamide. The preparation of the corresponding zinc (II) and cobalt (II) metallo phthalocyanines (3 and 4) substituted with 3-ferrocenyl-7-oxycoumarin moieties at beta-positions of the phthalocyanine ring was achieved by the cyclotetramerization of the coumarin ligand (2) with relevant metal(II) acetates in dry 2-dimethylaminoethanol. The new compounds have been characterized by elemental analyses, FT-IR, (1)H NMR, Mass and electronic spectroscopy. The fluorescence property of the zinc metallo phthalocyanine (3) is strongly affected by the presence of ferrocenyl moiety. The ferrocenyl moieties were very efficient in quenching the excited state of 3, which show very poor fluorescent intensity. The electrochemical properties of the complexes were also investigated by cyclic and differential pulse voltammetry techniques in non-aqueous medium. It was found that the redox-active ferrocene substituents are reduced concurrently at one potential. (C) 2011 Elsevier B.V. All rights reserved.Publication Metadata only Synthesis, photophysical, photochemical and electrochemical properties of crown ether bearing coumarin substituted phthalocyanines(ELSEVIER SCIENCE SA, 2012) ÖZKAYA, ALİ RIZA; Camur, Meryem; Durmus, Mahmut; Ozkaya, A. Riza; Bulut, MustafaZinc (II), cobalt (II) and copper (II) phthalocyanines substituted at the peripheral (complexes 5, 6 and 7) and non-peripheral (complexes 8, 9 and 10) positions with 7,8-(15-crown-5)-3-(4-oxyphenyl)coumarin groups have been prepared and characterized. The photophysical and photochemical properties of zinc (II) Pc complexes (5 and 8) were also described. The singlet oxygen quantum yields (0.54 for 5, 0.65 for 8) are indicating the potential of the complexes as photosensitizers in applications of PDT. The redox processes of the complexes were identified by voltammetry and in situ spectroelectrochemistry. Alpha and beta-substituted complexes displayed metal- and/or phthalocyanine ring-based redox processes. It was found that the kind of substitution affects the redox processes of the phthalocyanine complexes considerably, due to the difference in their aggregation behaviors. (C) 2011 Elsevier B. V. 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 Electrochemical, spectroelectrochemical and electrocatalytic properties of newly synthesized phthalocyanine compounds with 1,1 '-thiobis(2-naphthol) groups(ELSEVIER, 2019) ÖZKAYA, ALİ RIZA; Arucu, Seving; Saglam, Meltem Betul; Ozkaya, Ali RizaIn this work, the synthesis and characterization of new phthalocyanine compounds containing 1,1'-thiobis(2-napthol) units have been reported. The metal-free phthalocyanine, H2Pc 3 was synthesized by the cyclotetramerization of dinitrile derivative 2 in dry n-pentanol by a classical method. Metal phthalocyanines complexes, ZnPc 4 and CoPc 5 were prepared by the reaction of 2 with the corresponding anhydrous metal salts in n-pentanol and DBU. The structures of the original compounds were identified by using elemental analysis, H-1 NMR, C-13 NMR, IR, mass and UV-vis spectroscopic data. Electrochemical redox characteristics of the compounds were determined by electroanalytical techniques such as cyclic voltammetry, square wave voltammetry, and chronocoulometry. Extra support for the precise nomination of the electron transfer processes were also maintained with in situ spectroelectrochemical measurements. The compounds usually showed one-electron metal- and/or ligand-based reversible or quasi-reversible reduction and oxidation processes. The processes were found to be accompanied by distinct colour changes, indicating the possibility of the use of the compounds as electrochromic material. Electrocatalytic oxygen reducing performances of the compounds were also tested by dynamic voltammetry in a medium similar to fuel-cell working conditions. The CoPc compound showed high performance for electrocatalytic reduction of dioxygen to water through a process involving the transfer of totally 4 electrons per molecule in two different ways. (C) 2019 Elsevier B.V. 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.
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