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 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 and characterization, novel across adjacent ring formed phthalocyanine(ROYAL SOC CHEMISTRY, 2011) ÖZKAYA, ALİ RIZA; Elmali, Dilek; Altindal, Ahmet; Ozkaya, Ali Riza; Salih, Bekir; Bekaroglu, OzerNovel mononuclear Zn(II) 4, Co(II) 5 and Cu(II) 6 metallophthalocyanines have been synthesized from 4,4'(ethane-1,1-p-phenol-2,2-p-phenoxy) phthalonitrile 3, which can be obtained by the reaction of 4-nitrophthalonitrile 1 with 1,1,2,2-tetrakis(p-hydroxy-phenyl)-ethane 2. The target water-soluble derivatives of 7-9 were acquired from a boiling suspension of the compounds in aqueous 20% KOH solution. The synthesized complexes have been characterized by UV-vis, IR, H-1 NMRand MALDI-TOF-mass spectroscopies. In addition, the geometric and electronic structures of 2-6 were investigated by ab initio/DFT quantum mechanical calculations using the Gaussian 03 program with HF theory at the B3LYP/3-21G level. The redox properties of the complexes 4-6 were examined by cyclic voltammetry on platinum in DMSO/TBAP. These complexes displayed one-electron metallophthalocyanine-based and multi-electron hydroxyphenyl-based redox processes. The effect of temperature on the d.c. conductivity and impedance spectra of spin coated films of compounds were investigated at the temperatures between 300-452 K and in the frequency range of 40-105 Hz. Thermally activated conductivity dependence on temperature was observed for all compounds. A. c. results indicated that conduction mechanism can be explained by classical hopping barriers mechanism for all films.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 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 Electropolymerization and Electrochemical Pesticide Sensor Application of Metallophthalocyanines Bearing Polymerizable Morpholin Groups(ELECTROCHEMICAL SOC INC, 2016) ÖZKAYA, ALİ RIZA; Ozen, Umit Ergin; Keles, Turgut; Biyiklioglu, Zekeriya; Koca, Atif; Ozkaya, Ali RizaIn this paper, new metallophthalocyanines (MPc) were synthesized by cyclotetramerization of 4-{[4-(2-morpholin-4-ylethoxy)benzyl]oxy}phthalonitrile. To increase potential application of MPcs, redox active Co(II), Mn(III) and Ti(IV)O metal centers were preferred. MPcs were decorated with redox active and electropolymerizable {[4-(2-morpholin-4-ylethoxy)benzyl]oxy} substituents in order to coat the complexes with electropolymerization. Synthesized MPcs were characterized with UV-Vis, IR, H-1-NMR, C-13-NMR and MS (ES+ and MALDI-TOF) spectroscopies and voltammetry and in situ spectroelectrochemistry techniques. Voltammetric and in situ spectroelectrochemical analyses indicated that all complexes gave metal based reduction processes in addition to the Pc based processes. During oxidation reaction, all complexes were coated on the glassy carbon electrode (GCE) surface with oxidative electropolymerization reactions. Redox active and conductive GCE/MPc electrodes were constructed with the electropolymerization of MPcs and these electrodes were tested as active pesticide sensors for eserine, parathion, diazinon and fenitrothion pesticides. CoPc did not interact with any pesticide compound while MnPc and TiOPc selectively sensed diazinon and eserine, respectively. (C) 2016 The Electrochemical Society. All rights reserved.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.