Person: ÖZKAYA, ALİ RIZA
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ÖZKAYA
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ALİ RIZA
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Publication Metadata only Electrochemical, photovoltaic and DFT studies on hybrid materials based on supramolecular self-assembly of a ditopic twisted perylene diimide with square-planar platinum(II)- and/or palladium(II)-2,2 ':6 ',2 ''-terpyridyl complex ions(ELSEVIER SCI LTD, 2019) ÖZKAYA, ALİ RIZA; Buyukeksi, Sebile Isik; Orman, Efe Baturhan; Acar, Nursel; Altindal, Ahmet; Ozkaya, Ali Riza; Sengul, AbdurrahmanA ditopic bridging ligand, N,N'-bis(pyridine)-1,6,7,12-tetrakis-(4-methoxyphenoxy)perylene diimide (1) was synthesized. Metallosupramolecular self-assembly of 1 with 2,2':6',2 ''-terpyridyl-platinum(II) and/or -palladium (II) complex ions afforded to new triads [(terpy)M(II)-(1)-M(II)(terpy)1(NO3)(4) where, M(II) = Pt(II) (2), and Pd (II) (3), respectively. These isolated triads 2 and 3 and also free ligand 1 were fully characterized by FT-IR, H-1 NMR, C-13 DEPT NMR, H-1-H-1 COSY NMR, MALDI TOF and HRMS (MALDI-TOF/TOF-MS) mass techniques and UV/Vis spectroscopy. DFT studies revealed that the molecular structure of 1 is highly distorted and deviated from the planarity by bulky methoxyphenyl groups at bay positions. The calculated HOMO and LUMO are located on the PDI core and phenyl groups, and the band gap was found to be 2.27, 2.23 and 2.24 eV in DMSO for 1, 2 and 3, respectively. The calculated UV/Vis spectra are in good agreement with those of experimental results. Electrochemical, in situ spectroelectrochemical and in situ electrocolorimetric measurements in solution suggested that redox processes of the compounds are accompanied by favourable electron transport properties with remarkably narrow HOMO-LUMO gaps and intense light absorption over the visible range. The association of usually reversible and fast electron transfer processes with the net colour changes in solution pointed out the applicability of the compounds as an electrochromic material. The electrochromic performance measurements with the films of the compounds on indium tin oxide glass provided additional support for their usability as a colour changing material in electrochromic devices. Surface morphologies of the films were characterized by scanning electron microscopy (SEM). The metal complexes of 1, especially the platinum(II) complex (2), behaved as a good neutral and cathodic colouring electrochromic material with fast response time, long-term stability, and long-term write erase efficiency. The photovoltaic performance of the compounds as electron acceptor material was investigated by varying their relative ratio in the bulk heterojunction solar cells. It was found that the photovoltaic conversion efficiency of the devices strongly depends on the blend ratio. The optimized performance for the devices was obtained with the P3HT:PDIs (weight ratio 1.0:1.5) blended films. For this blend ratio, the device showed a maximum conversion efficiency of 3.91%, 8.17% and 5.18% for 1, 2 and 3, respectively. The results obtained reveal that employing 2 as an acceptor material has great potential for the development of highly efficient nonfullerene bulk heterojunction photovoltaic devices.Publication Metadata only Tiyobis-naftol sübstitüe metalli ftalosiyanin bileşiklerinin elektrokimyasal, spektroelektrokimyasal ve elektrokatalitik özellikleri(2022-10-12) CENGİZ, ERHAN ŞÜKRÜ; ORMAN, EFE BATURHAN; ODABAŞ, ZAFER; ÖZKAYA, ALİ RIZA; Cengiz E. Ş., Akdağ Ö., Zayin Ö., Orman E. B., Odabaş Z., Özkaya A. R.Yakın gelecekte yaşanabilecek enerji kıtlığı nedeniyle çevre dostu ve sürdürülebilir enerji sistemlerine ihtiyaç duyulmaktadır. Yakıt pilleri; sürdürülebilir ve temiz enerji için umut vadeden, yüksek özgül enerji yoğunlukları, enerji dönüşüm verimlilikleri, düşükten sıfıra emisyonları ve yüksek güvenlikleri nedeniyle büyük ilgi görmüştür. Ayrıca metal-hava pilleri, özellikle teorik enerji yoğunluğu mevcut Li-iyon pillere göre çok daha yüksek olan Zn-hava pili, çok daha ucuz ve güvenli olmakla birlikte, gelecek vadeden sistemlerdir. Oksijen indirgeme reaksiyonu (ORR) elektrokatalizörleri, bu sistemlerin genel performansını ve verimliliğini belirler. Sonuç olarak değerli Pt bazlı malzemelere alternatif olarak uygun maliyetli ORR elektrokatalizörlerinin geliştirilmesi bu sistemlerin uygulanabilirliği açısından önemlidir.Ftalosiyanin (Pc) kompleksleri, yüksek redoks aktiviteleri, kimyasal ve ısıl kararlılıkları ve ayrıca karbon malzemelerle yüksek uyumlulukları nedeniyle sıklıkla araştırılan umut verici adaylardandır. Karbon malzemelerle olan kompozitleri, yukarıda belirtilen sistemlerin katotları için oldukça aktif ve değerlidir. Bu çalışmada, 1,1`-tiyobis(naftalen-2-oksi) sübstitüe Pc komplekslerinin redoks davranışları voltametrik ve eş-zamanlı spektroelektrokimyasal ölçümler ile incelenmiş ve ardından MPc-karbon kompozitleri ile modifiye edilen camsı karbon elektrotlar (GCE) ile ORR\" ye yönelik katalitik aktiviteleri değerlendirilmiştir.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 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 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 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 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 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 Comparative Electrochemistry and Electrochromic Application of Novel Binuclear Double-Decker Rare Earth Metal Phthalocyanines Bearing 4-(hydroxyethyl)phenoxy Moieties(ELECTROCHEMICAL SOC INC, 2019) ÖZKAYA, ALİ RIZA; Guzel, Emre; Orman, Efe Baturhan; Koksoy, Baybars; Celikbicak, Omur; Bulut, Mustafa; Ozkaya, Ali RizaIn the present work, novel double-decker samarium(III), europium(III), and ytterbium (III) phthalocyanines (SmPc2, EuPc2, and YbPc2) bearing 4-(hydroxyethyl)phenoxy moieties have been synthesized and their electrochemical redox, spectroelectrochemical, and electrocolorimetric properties of the complexes have been inquired comparatively in two different non-aqueous solution. All complexes were observed to expose a series of usually reversible phthalocyanine ring-based one-electron reduction and oxidation processes. The effect of the size of rare earth metal ion was clearly reflected as the modest shift in half-wave potentials. Enriched electron transfer processes of the complexes and the interaction between the electrochemically generated anionic and cationic species caused distinct spectral and color changes, identified with in-situ spectroelectrochemical and in-situ electrocolorimetric measurements in solution medium. Spectroelectrochemical and electrocolorimetric measurements of the complexes were also performed in the solid state as the Langmuir-Blodgett film on an indium tin oxide glass in order to understand their technological applicability in electrochromic devices as color changing material. Comparative evaluation of these measurements suggested that Langmuir-Blodgett films of SmPc2 and EuPc illustrate highly reversible distinct color change from green to purple with satisfying electrochromic performance for electrochromic device applications. (c) 2019 The Electrochemical Society.
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