Person: ÖZKAYA, ALİ RIZA
Loading...
Email Address
Birth Date
Research Projects
Organizational Units
Job Title
Last Name
ÖZKAYA
First Name
ALİ RIZA
Name
105 results
Search Results
Now showing 1 - 10 of 105
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 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 Synthesis, characterization and electrochemical properties of novel metal free and zinc(II) phthalocyanines of ball and clamshell types(PERGAMON-ELSEVIER SCIENCE LTD, 2007) ÖZKAYA, ALİ RIZA; Ceyhan, T.; Altindal, A.; Ozkaya, A. R.; Celikbicak, O.; Salih, B.; Erbil, M. Kemal; Bekaroglu, O.The phthalodinitrile derivative I was prepared by the reaction of 4-nitrophthalonitrile and 1,3-dimethoxy-4-tert-butylcalix[4]arene in dry dimethylsulfoxide as the solvent, in the presence of the base K2CO3, by nucleophilic substitution of an activated nitro group in an aromatic ring. The tetramerization of compound I gave a binuclear zinc(II) phthalocyanine and a metal-free phthalocyanine of the ball type, 2 and 3, respectively. Its condensation with 4,5-bis(hexylthio)phthalonitrile results in a binuclear plithalocyanine of the clamshell type, 4. The newly synthesized compounds were characterized by elemental analysis, UV-Vis, IR, MS and H-1 NMR spectra. The electronic spectra exhibit an intense pi -> pi* transition with characteristic Q and B bands of the phthalocyanine core. The electrochemical properties of 2-4 were examined by cyclic voltammetry in non-aqueous media. The voltammetric results showed that while there is no considerable interaction between the two phthalocyanine rings in 4, the splitting of a molecular orbital occurs as a result of the strong interaction between the phthalocyanine rings in 2 and 3. (c) 2007 Elsevier Ltd. All rights reserved.Publication Metadata only Coumarin-derivatized fluorescent vic-dioxime-type ligand and its complexes; the preparation, spectroscopy, and electrochemistry(SPRINGER, 2007) ÖZKAYA, ALİ RIZA; Camur, Meryem; Bulut, Mustafa; Oezkaya, Ali R.; Kandaz, Mehmet; Yayli, NurettinA new vic-dioxime bearing coumarin functionality, N-'1, N-'2-Dihydroxy-N1, N2-bis(4-methyl-2-oxo-2H-chromen-7yl) oxalimidamid (LH2), N,N-bis-[4-methylcoumarinyl]-diamino glyoxime (LH2), and its mono- and dinuclear complexes {copper(II), cobalt(II), nickel(II) and uranyl(II)} have been reported. The. uorescence excitation and emission spectra of LH2 and its complexes with metal ions were examined. It was observed that. uorescence and excitation emission intensity of LH2 was quenched depending on complex formation with metal ions. The characterizations of all newly synthesized compounds were made by elemental analysis, H-1-n.m.r,i.r.,u.v.-vis., and l.c-m.s. m.s. data. Electrochemical behaviour of the ligand involving oxime and coumarine moieties, and its complexes with Ni-II, Cu-II, Co-II and UO2II were investigated by cyclic voltammetry. The comparison of the electrochemical behaviour of the ligand with its complexes enabled us to identify metal-, oxime- and coumarine-based signals.Publication Open Access Fluorescent vic-dioxime-type ligand and its mono- and dinuclear complexes: The preparation, spectroscopy, and electrochemistry of its various complexes(ELSEVIER SCI LTD, 2008-01) ÖZKAYA, ALİ RIZA; Oezer, Metin; Kandaz, Mehmet; Oezkaya, Ali Riza; Bulut, Mustafa; Gueney, OrhanA new coumarin functionalized vic-dioxime, S,S-bis-[4-methylcoumarinyl]-dithioglyoxime (LH2), and its soluble mono- and dinuclear complexes [nickel(II), copper(II), cobalt(II), and uranyl(II)] have been reported. The fluorescent properties of the ligand and its complexes are due to the 7-mercapto-4-methylcoumarin fluorophore, which is conjugated with vic-dioxime that functions as the MN4 core. Fluorescence spectra of the probe showed a clear shift in excitation wavelength maxima upon metal binding indicating its potential use as ratio-metric metal indicator. The fluorescence of complexes was found to be highly sensitive to both polarity and protic character of the solvent used. Both mononuclear (LH)(2)M (M = Ni, Cu and Co) and homodinuclear (LH)(2)(UO2)(2)(OH)(2)) complexes have been obtained with the metal ligand ratios of 1:2 and 2:2, respectively. The characterizations of all newly synthesized compounds were made by elemental analysis, H-1 NMR, FT-IR, UV-vis, and mass (LSI-MS) data. The electrochemical investigation of the Ni(II), Cu(II), Co(II) and UO2(II) Complexes in comparison with the ligand involving oxime and coumarin moieties enabled us to identify metal-, oxime- and coumarin-based signals. (C) 2006 Elsevier Ltd. All rights reserved.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 Synthesis and electrochemistry of soluble phthalocyanine complexes containing four peripheral dihexyl and dihexylhexylmalonate residues(SPRINGER-VERLAG WIEN, 2001) ÖZKAYA, ALİ RIZA; Kandaz, M; Ozkaya, AR; Bekaroglu, OTetrasubstituted phthalocyanines bearing four dihexylmalonate or dihexylhexylmalonate residues on the periphery (M[Pc(CH(COOC6H13)(2))(4)] or M[Pc(C(COOC6H13)(2)C6H13)(4)]; M = Pd(II), Cu(II), Co(II)) were synthesized from the anhydrous metal salts and the corresponding phthalonitriles. The complexes were only slightly soluble in polar solvents such as methanol and ethanol, but more soluble in less polar solvents such as benzene, toluene, and even hexane. The spectroscopic properties of the complexes were affected strongly by the electron withdrawing malonate units. Cyclic voltammetry on a platinum electrode in dichloromethane showed ligand-based one-electron transfers for Cu and Pd compounds, whereas the Co complex displayed metal-based or/and ligand-based one-electron transfers depending on the supporting electrolyte anion. The structures were confirmed by elemental analysis, H-1 NMR, C-13 NMR, IR, mass (EI and FAB), and UV/Vis spectroscopy.Publication Metadata only A new redox-active multisite ligand: synthesis, spectroscopy and electrochemistry of its mono and dinuclear complexes, and the interaction of (E,E)M (M = Ni) complex with Pd-II and Ag-I(PERGAMON-ELSEVIER SCIENCE LTD, 2004) ÖZKAYA, ALİ RIZA; Kandaz, M; Koca, A; Ozkaya, ARA novel redox active (E,E)-dioxime ligand, S,S-bis-[2(2'-ferrocenemethylaminobenzyl)]-dithioglyoxime (LH2), containing ferrocene and flexible aminobenzenesulfanyl-moieties on the periphery has been synthesized from 2-(2'-ferrocenemethylamino)benzenethiol. which was obtained by the reduction of 2,2-pyridylbenzothiazolidine with a large excess of NaBH4. Mononuclear (LH)(2)M (M = Ni-II, Cu-II, Co-II, Fe-II and Mn-II), homodinuclear (LH)(2)(UO2)(2)(OH)(2) and heterotrinuclear (LH)(2)MM'X-2(n) (M = Ni-II and M' = Pd-II, X = Cl-, n = 4 and M' = Ag-1, X = NO3-, n = 2) complexes have been obtained with the metal:ligand ratios of 1:2, 2:2 and 3:2. respectively. Flexible ferrocenemethylaminobenzenesulfanyl moieties bearing two different heteroatoms, -S and -N, on the periphery of the vic-dioxime serve as weak binding sites for Pd-II and Ag-I ions. The detection of H-bonding in all complexes except the uranyl complex by IR revealed square-planar MN4 coordination of the mono- and trinuclear complexes. The MN4 coordination of the Ni-II complex was also determined by the H-1 NMR spectroscopy. The structures of the complexes were characterized by elemental analysis, H-1 NMR, IR, MS, UV-Vis spectral and cyclic voltammetry. The voltammetric analyses of the complexes showed metal, ligand, and ferrocene based signals. The redox chemistry of the complexes exhibited both M-I and M-III oxidation states of the central metals of the complexes. (C) 2004 Published by Elsevier Ltd.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.