Person: ÖZKAYA, ALİ RIZA
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ÖZKAYA
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ALİ RIZA
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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 Synthesis and electrochemical, electrochromic and electrical properties of novel s-triazine bridged trinuclear Zn(II), Cu(II) and Lu(III) and a tris double-decker Lu(III) phthalocyanines(ELSEVIER SCIENCE SA, 2011) ÖZKAYA, ALİ RIZA; Sen, Pinar; Dumludag, Fatih; Salih, Bekir; Ozkaya, Ali Riza; Bekaroglu, OzerThe new s-triazine-bridged trinuclear Zn(II) and Cu(II) phthalocyanines have been synthesized from the reaction of corresponding anhydrous metal salts, Zn(OAc)(2) and CuCl with 4,5-bis(hexylthio)-phthalonitrile and 2,4,6-tris(2-thiophthalonitrile)-s-triazine. The tris phthalonitrile derivative of s-triazine was prepared from the reaction of 4-nitrophthalonitrile and thiocyanuric acid in dry dimethylformamide as solvent using K2CO3 as the base. The same route was applied to prepare the trinuclear Lu(III) phthalocyanine analogue. The conversion of tris phthalonitrile into its isoindoline derivative was accomplished by bubbling ammonia gas through a solution in methanol in the presence of sodium methoxide. The cyclization of two different isoindoline derivatives and 4,5-bis(hexylhthio)-1,2-diiminoisoindoline, with lutetium (III) acetate in dimethylformamide gave trinuclear Lu(III) phthalocyanine. The reaction of this complex with octakis-hexylthio phthalocyanine led to the isolation of tris double-decker Lu(III) phthalocyanine. The structures of the target compounds were confirmed by elemental analysis, UV-vis, IR and MALDI-TOF mass spectroscopies. The d.c. and a.c. conductivities of the phthalocyanine compounds were measured as a function of temperature. The small value of pre-exponential factor suggested the conduction by localized states in the band tails and by localized states near the Fermi level. The temperature dependence of the frequency exponent showed that the conduction in these compounds is due to hopping of charge carriers. The tris double-decker phthalocyanine complex showed well-defined electrochromic behaviour with green-blue and blue-purple colour transitions. (C) 2011 Elsevier B.V. All rights reserved.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 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 Spectroscopic, electrochemical and electrocolorimetric properties of novel 2-(2 '-pyridyl)-1H-benzimidazole appended bay-substituted perylene diimide triads(ELSEVIER SCIENCE SA, 2019) ÖZKAYA, ALİ RIZA; Pekdemir, Fatih; Orman, Efe Baturhan; Selcuki, Nursel Acar; Ozkaya, Ali Riza; Salih, Bekir; Sengul, AbdurrahmanIn this study, four new perylene diimide (PDI) derivatives incorporating 2-(2'-pyridyl)-1H-benzimidazole (2PBI) chromophores at the imide positions, in which 1 bearing non-bay-substituted perylene core, and those having four substituents at 1,6,7,12-bay positions of the perylene core, namely 2 bearing electron-withdrawing chlorine atoms, 3 bearing electron-donating 4-methoxyphenoxy groups and 4 bearing non-electron-donating 4-tert-butylphenoxy groups, respectively were synthesized and fully characterized by FT-IR, H-1 NMR, C-13 NMR, MALDI-TOF mass spectrometry and UV/Vis spectroscopy. The thermal properties were measured by thermogravimetric analysis (TGA) which showed that the materials (1-4) are thermally very stable (T-d > 450 degrees C). DFT was performed for geometry optimizations, and TDDFT was used to compare the calculated and the experimental UV/Vis electronic spectra at the B3LYP/6-311 G(d) level. Detailed measurements were carried out by the use of electroanalytical, spectroscopic and colorimetric techniques in order to understand redox natures, color changes and optoelectronic characters of the novel compounds. These 2PBI-functionalized PDI triads showed reversible reduction processes, chemically stable reduced species and considerably low HOMO-LUMO band gaps, as the new worthy members of photoactive charge transport materials for optoelectronic and photovoltaic systems. In addition, with distinct color changes associated with their redox processes in the solution, these new triads displayed great capacity for application in electrochromic devices. The emission maxima of the compounds were found to be red shifted in the solid state.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 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 Metadata only Electrochemical pesticide sensors based on electropolymerized metallophthalocyanines(ELSEVIER SCIENCE SA, 2017) ÖZKAYA, ALİ RIZA; Akyuz, Duygu; Keles, Turgut; Biyiklioglu, Zekeriya; Koca, AtifNew metallophthalocyanines (MPcs) were designed with redox active Co(II) (CoPc(ma)), Cl-Mn(III) (Cl-MnPc(ma)), and Ti(IV)O (TiOPc(ma)) metal centers and morpholin and amino bearing substituents (ma). While redox active metal centers enhanced redox activity of the complexes, redox active and electropolymerizable [2-(4-{[(1E)-(4-morpholin-4-ylphenyl)methylene]amino}phenyl)ethoxy] substituents triggered the coating of MPcs with the oxidative electropolymerizations. Voltammetry and in situ spectroelectrochemistry techniques were used for the electrochemical characterizations of MPcs. All complexes gave metal based reduction processes in addition to the Pc based processes. Moreover, all complexes were coated on GCE with the oxidations of morpholin and amino moieties of the substituents, thus redox active and conductive GCE/MPc(ma) electrodes were constructed. Modified electrodes were investigated as the potential pesticide sensors. Changing the metal center of the complexes significandy altered their sensing activities. While all complexes showed interaction abilities for chlorophyros, fenitrothion, and methomyl. GCE/CoPc(ma) electrode sensed fenitrothion with good selectivity and sensitivity. A linear range for the fenitrothion sensing with GCE/CoPc(ma) electrode was observed between 1.20 mu moldm(-3) and 42.0 mu moldm(-3) concentrations. Moreover, sensitivity and LOD of the electrode were found as 0.26 Acm(-2) M-1 and 0.46 mu moldm(-3) respectively. Although GCE/TiOPc(ma) electrode also sensed fenitrothion with a good selectivity, the linear range of this sensing was very narrow. GCE/Cl-MnPc(ma) electrode sensed all pesticides with similar voltammetric responses, thus its selectivity is poorer than the others, although it has good sensitivity for the pesticides.
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